HUMAN POWER TECHNICAL JOURNAL OF THE IHPVA NUMBER 53, SPRING 2002
From the editor ...... 2 A brief introduction, Theo Schmidt ...... 2 Contributions to Human Power ...... 2 Articles Comparison of measurements of bicycle spoke tension using a mechanical tensiometer and musical pitch John S. Allen ...... 3 Adding arm power to a recumbent Daniel Kirshner ...... 7 Bicycle design, safety, and product-liability litigation David Gordon Wilson ...... 10 Letters Human-powered trackway systems John Barber ...... 6 Demise of rickshaws ...... 19 Independent feelings of water molecules George Tatum ...... 19 Arm-powered tricycle, Mike Eliason ...... 20 Theo’s mini ice-scooter, Theo Schmidt ...... 21 Future of the HPVA?, John Snyder ...... 23 The future of Human Power, Jean E. Anderson...... 23 Book reviews Von Null auf 140 mit 93 Zähnen: Aerodynamik von Pedalfahrzeuge by Andreas Pooch reviewed by Theo Schmidt ...... 22 The Recumbent Bicycle by Gunnar Fehlau; translated Number 53 by Jasmin Fischer; reviewed by Dave Wilson ...... 22 Spring 2002 $5.50 Comparison of measurements of bicycle spoke tension HUMAN POWER using a mechanical tensiometer and musical pitch Number 53 Spring 2002 $5.50/IHPVA members, $4.50 by John S. Allen Abstract double-crossed, not laced, 215 mm. root of tension. Therefore, every A brief introduction FROM THE EDITOR he tension of 140 spokes in four This wheel had a steel rim and a very doubling of frequency — one musical I am 48 and live with my wife in an This issue of Human Power is a bit bicycle wheels was measured wide range of spoke tensions. octave — raises the tension by a fac- HUMAN POWER old house in the foothills of the Bernese different. David Gordon Wilson has using a tensiometer — a • A 406 mm 36-spoke wheel with 14/15 tor of 4. A spoke whose fundamental is the technical journal of the Alps near Lake Thun. It’s full of parts T asked me to take over as editor at least mechanical device designed to measure gauge (~1.8 mm diameter) spokes, frequency is only 1.2 times as high as International Human Powered from human- and solar-powered vehicle for a while, as he is involved in starting spoke tension —and by plucking triple-crossed, 183 mm. the value given in the table — a musical Vehicle Association and boat projects. I grew up near a company building small gas turbines the spokes like harp strings and Using wheels with different spoke minor third higher — is already under Number 53, Spring 2002 Mount Tamalpais in California, where and in completing the third edition of determining their tension using the lengths, patterns and tensions made it more than 1.4 times as much tension, Editor mountain biking started, and studied in Bicycling Science. Dave Wilson has standard formula for the fundamental possible to determine how these fac- and is likely to fail quickly. Theodor Schmidt Basel and in hilly Wales and England, made Human Power into the world’s frequency of vibration of stretched tors affected the relationship between Bicycle spokes rarely break due to Ortbühlweg 44 where I was introduced to HPVs. premier technical journal wires. The measurements by the two the tensiometer measurements and excessive tension; but the rim may not CH-3612 Steffisburg, Switzerland on HPVs, (including HPBs, methods were compared. When spokes musical measurements. withstand it, and when the rim relaxes [email protected] around the spoke holes, the wheel fails. HPAs) and also some sta- were laced such that they touched each The musical method Associate editors other, the musical measurement was Weight loading on a wheel decreases tionary applications of The fundamental frequency of vibra- David Gordon Wilson of the average tension of a laced pair, tension of the few spokes at the bottom human power. If there were tion of a stretched string or wire varies 21 Winthrop Street and so there were 93 rather than 140 of the wheel greatly, and raises ten- a knighthood for human according to the following equation, Winchester, MA 01890-2851 USA musical measurements. Tensiometer sion of the remaining spokes only very power, he would deserve it! assuming small amplitudes [1]: [email protected] measurements of laced spokes were slightly, but lateral loading while pedal- I would like to broaden where averaged for comparison with the ing out of the saddle causes significant Toshio Kataoka, Japan our scope to include 1 1-7-2-818 Hiranomiya-Machi articles to do with the phi- musical measurements. F = the fundamental frequency [Hz] increases in spoke tension and can lead Hirano-ku, Osaka-shi, Japan 547-0046 losophy of human power. Both types of measurements proved 1 T to rapid failure of an over-tensioned F1 = wheel. On the other hand a common [email protected] There are two reasons for accurate enough to use in establishing 2L m this. Firstly, we are getting the correct tension of spokes when error in wheel building is to leave the Philip Thiel, Watercraft L = the length of the string spoke tension too low, resulting in a 4720 - 7th Avenue, NE less material than before building bicycle wheels. The function T = tension of the string weak wheel, since spokes go slack Seattle, WA 98105 USA as HPV physics become relating the measurements conducted more and more specialised; using the two methods is linear and m = mass per unit of length under smaller loads, and fail to hold Production the rim steady. The excess motion in a and secondly, the status of consistent, though there was some This resolves to T = 4 F12 L2 m JS Design & JW Stephens human power in society is a discrepancy between the results. Each which is used to calculate the tension slack wheel is what breaks the spokes IHPVA precarious one and we need method proved to have strengths and from the measured frequency. and allows the nipples to unscrew. Paul MacCready, Honorary president to give it all the support weaknesses related to convenience, The cross-sectional area of the spoke As the Paul Gracey, USA, Chair, we can in order to improve which will be discussed. and the mass per unit length m are thickness Table 1.
Open, Secretary/treasurer the quality of life in present Patient Jason exactly proportional to each other. of a wire Length Length My own projects have mostly been The wheels used increases, our Publisher and future societies. Please send your in the investigation Therefore, for two different strings or (mm), (mm), Musical articles and letters. human-solar hybrid vehicles and boats wires of equal length, one thick and equation for plain butted pitch IHPVA The tension of the 140 spokes of Human Power continues to be and formerly racing these in the Tour another thin, the frequency is the same musical pitch PO Box 1307 four bicycle wheels was measured. The 308 F# San Luis Obispo, CA 93406-1307 USA produced by Jean Anderson and John de Sol. These have always been either if the tension per unit of cross-sectional becomes wheels were: 292 G [email protected] (Elrey) Stephens of the HPVA. It is sent easily transportable or semi-amphibi- area is the same. One way to think of slightly • A 622 mm, 40-spoke dished rear wheel to HPVA members together with HPV ous in order to tour without being car- this is to imagine two identical spokes inaccurate 276 308 G# Human Power (ISSN 0898-6908) is with 14 gauge (~2.0 mm diameter) because the News (now edited and produced by dependent. I’m vice president of Future side by side, both of the same gauge A, published irregularly for the Inter- plain gauge spokes on the right side 262 292 Peter Eland of VeloVision) and is avail- Bike Switzerland, where one of our and at the same tension. They vibrate greater bend- 440 Hz national Human Powered Vehicle and 14/16 gauge butted spokes on able for subscription to all other IHPVA specialties is organising races for HP at the same frequency. Now imagine ing stiffness Association, a non-profit organization the left side (~1.6 mm diameter over 248 276 A# members at reduced rates. rail vehicles. lightly connecting them together all adds its con- dedicated to promoting improvement, most of the length, ~2.0 mm near — Theo Schmidt along their length. They still vibrate at tribution to 236 262 B innovation and creativity in the use of both ends); both sides quadruple- Steffisburg, Switzerland the same frequency. Finally, imagine the stiffness 224 248 C human power generally, and especially crossed, spoke length 296 mm. merging them into one, thicker spoke. generated in the design and development of • A 630 mm, 36-spoke wheel with 14/15 212 236 C# It still vibrates at the same frequency. by the wire’s human-powered vehicles. gauge (~1.8 mm diameter) butted Contributions to Human Power These facts greatly simplify the tension. The 201 224 D spokes on both sides. One side is Material in Human Power is copyrighted measuring of spoke tension for wheel discrepancy 191 212 D# The editor and associate editors (you may choose with whom to correspond) welcome laced triple-crossed and the other by the IHPVA. Unless copyrighted also by builders. To determine whether a spoke is not large the author(s), complete articles or repre- contributions to Human Power. They should be of long-term technical interest. News is laced radially. Spokes on both 181 201 E is optimally tensioned, we don’t have to and only sentative excerpts may be published else- and similar items should go to HPV News or to your local equivalent. Contributions sides are 296 mm long. (Same length 172 191 F measure the thickness or, what is more amounts to where if full credit is given prominently should be understandable by any English-speaker in any part of the world: units should despite the difference in pattern difficult, the tension, since the musical a few per- 163 181 F# to the author(s) and the IHPVA. Individual be in S.I. (with local units optional), and the use of local expressions such as “two-by- because the hub flanges are of differ- pitch translates directly into the ten- cent. Table 1 subscriptions and individual issues are fours” should be either avoided or explained. Ask the editor for the contributor’s guide ent sizes). 156 172 G (available in paper, e-mail and pdf formats). Many contributions are sent out for review sion per unit of cross-sectional area. includes available to non-IHPVA and non-HPVA • A 451 mm, 28-spoke wheel with 14- 147 163 G# by specialists. We cannot pay for contributions. Contributions include papers, articles, Note that the fundamental frequency a correc- members. gauge (~2.0 mm diameter) spokes, technical notes, reviews and letters. We welcome all types of contributions from IHPVA of a spoke increases only as the square tion which I 156 A members as well as from nonmembers.
2 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 3 determined empirically by measuring Both the musical method and the for bending stiffness. However, tension form reasonably well reflects the ten- linear over a 10 to 1 range of spoke the musical pitch of tensioned spokes tensiometer method as used in building and bending stiffness affect the read- siometer’s response to spoke tension, tension, for spokes of differing lengths clamped off at different lengths. wheels tend inherently to have a quan- ing of the tensiometer similarly, and so so that the parameters of the smoothed of all three spoke gauges, laced or Part of a spoke at the outer end is tization error. In the musical method, adjustments in the parameters of the curves may be used to calculate a unlaced. inside the spoke nipple, and part at it is the tendency to assign a musical formula should be able to compensate spoke tension that corresponds to any 2. A perfect correspondence between the inner end is in contact with the pitch to the nearest musical semi-tone. for differences in bending stiffness tensiometer reading. The tension is cal- the musical and tensiometer readings hub. These parts do not contribute With the tensiometer, it is the tendency quite well. It is to be expected that the culated by inserting the values of a, b would produce the function to the vibrating length. The table also to assign the tension to the nearest values of b and c will vary with spoke and c for the appropriate spoke gauge y= x accounts for this. The ends of a butted calibration table entry. Interpolation gauge, reflecting the differences in into the equation for tension, along where y is the tensiometer measure- spoke are sufficiently thicker than the is possible, but requires higher musi- spoke thickness and bending stiffness. with the tensiometer reading y. This ment and x is the musical tension mea- shaft of the spoke so that the ends Figure 2. In use, one arm of the cal skill with the musical method, and The parameters a, b and c of the results in a calculated tension for each surement. contribute only slightly to its effective tensiometer is hooked under the spoke mathematical calculation when using equation above were adjusted by eye to spoke examined. The actual function (in Newtons) is vibrating length. This, and the greater and the other is pressed down until it the tensiometer. produce smoothed curves for Using the musical method, the approximately strength at the threads and head of a just touches the spoke, depressing the When curve fits are used in deriving 14-, 15- and 16-gauge (~2.0, ~1.8, and tension can be calculated for indi- y=1. 2 x − 200 butted spoke, account for the higher central plunger against spring restoring a tension measurement from the ten- ~1.6 mm diameter) spoke shafts, which vidual spokes in a wheel with radial musical pitch recommended for butted force and producing a dial reading. The siometer reading, quantization error is conformed as well as possible to the or unlaced spokes, but in a wheel with The causes of this difference in spokes. tension must be read from a calibration no longer an issue, and the “noise” of tensiometer calibration readings. The laced and touching spokes, it can be measurements could be in either the The yield strength of good steel is table, as the reading is a nonlinear the calibration tables is smoothed out, comparison between the calibration calculated only for each laced pair, tensiometer or the musical method, or about 150 000 pounds per square inch function of tension, spoke thickness though errors in curve fit may occur. readings and the smoothed curves are which resonates as a unit. both, and can not be determined with- and spoke bending stiffness. or 1 040 N/mm2, and the tension recom- shown in the calibration graph (fig. 4). Though a tensiometer measurement out measuring the tension of accurately mended in the table is 1/3 this — about ing stiffness. The tensiometer used for The vertical scale of the graph is loga- is available for each spoke, a tension tensioned spokes, for example, spokes as high as you can take the tension and this investigation was supplied with a rithmic, reflecting the fact that the ratio reading for each laced pair of spokes supporting a hub from which weights still leave an adequate margin of safety. calibration chart, with a different set rather than the difference between the must be derived in order to make a are suspended. It is, however, most In the following comparison with the of readings for different spoke gauges. calibration reading and the height of comparison against the musical read- likely that the offset in the crossing of tensiometer measurements, I used a No information was provided as to how the smoothed curve is to be kept as ings. The combined tension reading is the y axis is due to an error in the zero Figure 3. Geometric model of the length adjustment of 3 cm for all spokes the chart was developed, but appar- small as possible. the average of the tensions of the two setting of the tensiometer calibration, tensiometer in this investigation (reduced vibrat- ently one or more readings were taken As can be seen, the fit of the spokes. because frequencies of vibration inher- ing length to account for the effects of from spokes whose tension had been In order to generate the curve fits, smoothed curves for all three spoke The values of tension using the musi- ently correspond accurately to tension bending stiffness), and used the musi- premeasured, at each of several ten- a geometric model of the tensiometer gauges is quite good. It does appear cal and tensiometer methods may now ratios. cal method to measure existing spoke sions. was developed (fig. 3). that the smoothed curves for the lighter be compared. The results of the com- 3. Both the musical method and the tensions rather than to adjust a wheel Because of the effect of bending As apparent from figure 3, the ten- gauge spokes may be a bit low near the parison are shown in figure 5. tensiometer are accurate enough for for optimum working tension. sion on the spoke relates to the force low end of the tension range, and high use in establishing the correct ten- stiffness and the geometry of the ten- Conclusions siometer mechanism, it is clear that on the probe as near the high end. However, given the sion level of spokes in wheel building. The tensiometer method 1. As can be seen in the graph, there the tensiometer readings should form FT= 2 sin Θ noisiness of the calibration readings, However, the accuracy of both mea- The tensiometer (fig. 1, 2) is a are a few outliers, which most likely a nonlinear function of spoke tension, no firm conclusion can be reached on surement means could be improved mechanical device which contacts the or result from recording errors rather and in fact, they do. But a graph of the this issue. There is, however, a wide by accurate calibration. In the case of spoke at three points. The middle one than measurement errors, considering calibration readings shows clearly that 2Ty variation in the constant a between the the musical method, calibration would of these points is the tip of a probe F = their extreme values and small num- the calibration measurements are also y2+ a 2 different spoke gauges. serve to establish accurately the length which is pressed against the spoke by ber. Aside from these, the correlation somewhat “noisy”— they do not form The goal of the modeling is in any compensation which is necessary to a spring. The higher the tension of the where T is the tension, y is the posi- between the musical and tensiometer a smooth curve. The inconsistencies case only to derive a formula whose account for bending stiffness for the spoke, the less it is flexed out of line by tion of the tensiometer probe, F is the readings is tightly grouped and nicely in measurement might be due to fric- different spoke gauges. the probe. A reading of the probe posi- force on the probe and a represents the tion in the tensiometer’s mechanism, tion is taken from a dial gauge which length of the spoke between the probe friction between the spoke and the ����� ���� registers the probe position. and the support at each side of the ������������� tensiometer probe; inconsistencies ���������������� tensiometer’s arch. �������� ���� ����������������� in thickness of spokes that are nomi- The force on the tensiometer probe varies ����������������� �������������� �������� �������������������� ���� nally of the same gauge; variation the as ����������������� ������������������ position of the tensiometer along the �������� ���������������� spoke; nonlinearity in the tensiometer’s F= b()y + c ����������������� ���� �����������������������
response, or perhaps other factors. where b is a constant which represents ���� the spring rate of the tensiometer Comparing the methods ���� probe and c is a constant represent- ���� In order to compare the tensiometer ing the position of the probe when the ����������� reading of spoke tension with the value ��� spring is at rest. calculated using the musical method, it Now, equating the force, F in the ����������������������� ��� Figure 1. The Hozan Tool Industry, Inc. is necessary to interpolate between the equations above, and solving for T, we spoke tension meter C-737 used in points in the tensiometer calibration this investigation obtain: ��� chart. If it is assumed that the “noise” The response of the tensiometer in the tensiometer calibration results b() y + c y2+ a 2 ��� differs with spoke thickness, because from measurement error, then the best T = ��� 2y � �� �� �� �� ��� ��� ��� ��� � the increased thickness displaces the interpolation is a smooth curve whose � ��� ��� ��� ��� ���� ���� ���� ���� ���� ���� tensiometer probe more, and because form reflects on the tensiometer’s The geometric model accounts for ���������������������������������������������������� ������������������� geometry. spoke tension and thickness, but not thicker spokes also have greater bend- Figure 4. Tensiometer readings vs. tension [N] Figure 5. Musical vs. tensiometer measure [N]
4 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 5 4. There are strengths and weak- between the tensiometer and musical investigation, and for the loan of a nesses to both methods. The musical measurements might be identified. tensiometer; David Gordon Wilson and Adding arm power to a recumbent method is much faster than using the 2. Providing a more sophisticated Sheldon Brown for their encourage- tensiometer, and the musical pitch modeling based on a larger sample ment, and Jobst Brandt for the back- by Daniel Kirshner relates directly to the optimum working of calibration readings, accounting ground information in his book The disadvantage of recum- vertical dur- tension of spokes based on their stress for bending stiffness, and using a Bicycle Wheel [2] and for his doubts bents — the rider can’t rise out ing the rowing per unit of cross-sectional area, regard- curve-fitting algorithm rather than an about the musical method, which fur- A of the saddle in a sprint — can be stroke). The less of the spoke gauge. However, the eyeball comparison would certainly ther motivated me to investigate it. turned to advantage. The recumbent handlebar clamp musical method requires musical train- produce a more accurate correspon- holds bearings References riding position allows use of the ing. When spokes are laced and touch- dence between the readings and the arms to add power to the bike… if a mounted on the ing, the musical method as used in this smoothed curves. [1] The derivation of this formula is practical way to do so can be found. I steering axle. investigation does not measure the 3. Perform musical measurements on given, for example, in Alonso and have developed a working prototype Power take-off tension of individual spokes, but rather, accurately measured spokes (for exam- Finn, Fundamental university phys- that allows this. Arm power gives an average tension reading for ple, using a hub from which weights ics, vol. 2, “Fields and waves” (1967, The most surprising aspect of the is transmitted each pair of laced spokes — sufficient are suspended) so as to identify an Addison Wesley), section 18-7. design is how easy it is to both steer through the hor- to measure the tension level of a wheel accurate function of musical pitch as it [2] Brandt, Jobst. 1993. The bicycle and power the bike at the at same time. izontal axle to as a whole, but not as useful for iden- relates to tension and spoke length. wheel, 3rd ed. Menlo Park, CA: The arrangement however also appears a short “crank tifying individual spokes which are too 4. Provide a statistical analysis of Avocet. (ISBN #0-9607236-6-8) to be surprisingly effective in allowing arm” attached tight or loose. (It is possible, though results. About the author me to put more of my human power to the end of the axle on the more difficult, to measure the tension 5. Measure a number of different John S. Allen
6 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 7 back-and-forth power stroke to allow me to increase my fortable to power. Nevertheless, I still of the handlebars thus has power output. didn’t feel that my arms were contribut- Table 2. Comparisons: short uphill sprint kg kg sec. % kg % no effect on the steering (or I knew that I would want ing enough. I have kept a 1:1 ratio since seconds bike total slower slower heavier heavier a negligible effect when the to experiment with different then. Best Schwinn upright 21.34 19.5 83.4 0.66 3.2% 7.3 10% steering motion moves the ratios between the arm “row- How well does it work? Best Brompton upright 20.68 12.2 76.2 — — — — bearing position slightly off ing” speed and the leg rotation Best recumbent arm & legs 22.28 15.4 79.4 1.60 7.7% 3.2 4% the axis). speed. The stationary trainer The bike seems to work very well: Best recumbent legs only 23.21 15.4 79.4 2.53 12.2% 3.2 4% You might be able to see in convinced me that I wanted you definitely feel like you are add- the photographs that the proto- my arms going “half as fast” ing power with your arms, and I can use higher gears on hills. But is there arm power the recumbent was 3.5 at about 130 beats per minute, to a type handlebars are construct- as my feet. I also thought that minutes or so behind the same bike difficult to maintain 29 miles per hour ed from modified aero-bars any faster movement of my an advantage? How big is the effect, if any? Finally, over the long run, you with arm power. at about 182 beats per minute — the clamped to a horizontal tube. arms would make it that much Table 2 shows comparisons for a use or non-use of arm power made no Weight harder to steer. Of course, the would expect to be limited by your aerobic capabilities, so you might not brief, approximately 20-second, uphill difference. I conclude that my heart In its current form the stationary bike told me noth- sprint. I did the sprint about three or rate, at least, closely reflects the power arm-power mechanism adds Figure 3. Diagram showing the main feaures of the mechanism ing about whether it would be expect any advantage except in short- term sprints. four times on each bike/configuration. requirement, however it is achieved. approximately 1.4 kg (3 lb) possible to both power and Table 2 reports the best times, and also Combining these results with my to the bike, not counting the opposed to the “forced rowing” mecha- steer a bike at the same time. I’ve been the only rider so far, so the nism discussed above). The linear tests are limited. I have three differ- some statistics on the percentage com- subjective impressions, the arm power intermediate/crossover drive, which Designs parisons of the times and weights of appears to allow me to exercise at a itself adds about 0.5 kg (1 lb). A refined rowing motion is transmitted directly The first design I chose to build was ent results to report: (1) comparisons to the hub, with a ratcheting/freewheel among my recumbent with arm power, the bikes and rider (who was approxi- higher aerobic level, less limited by the design (eliminating the aero-bar similar to the mechanism described mately 63.9 kg (141 lbs) in each case). capability of my leg muscles over lon- clamps, for example), could probably mechanism for the return stroke. Such above, except that the handlebar unit without arm power, and upright bicy- a mechanism does not decelerate the cles on a half-hour uphill ride; In this case, the upright bicycles ger periods. Certainly, when I made the save 0.5 kg, and under “Future develop- did not have a vertical axle. Instead, are definitely ahead of the recumbent. half-hour hill climbing comparisons, my ments,” below, I discuss plans to elimi- rower’s feet or arms at the end of the both vertical handles could twist about (2) similar comparisons on a very brief stroke. I have not seen information that uphill sprint; and (3) heart rate com- The percentage comparisons support legs ached a great deal more without nate the crossover drive. In this case their own axes. A steering linkage the advantage of uprights in the short the arm power. It remains to be seen the net weight addition should be about compares the performance of these much like a car’s — with link rods to parisons between using and not using bikes with other legs-only machines. arm power on a trainer. sprint. While my heavy old Schwinn whether this will be true for other rid- 1 kg (2.2 lb). each side — transmitted the twisting makes that configuration 10% heavier ers, and under different conditions (for Gardner Martin has built several motion through an “idler” to a fore-aft Table 1 shows comparisons among Arm power background modified Easy Racers [Tour Easys] that my recumbent with arm power, without than the lightest, fastest bike — the example, a longer exercise period). link to the front of the bike. Brompton — it’s only 3.2% slower, while Nevertheless, in short sprints, the abil- I was intrigued by the notion of add- put hand cranks in place of the handle- This prototype proved to be unride- arm power, and an upright bicycle on a ing arm power to bicycles by ergometer bars. The hand cranks are connected half hour uphill ride. It’s a challenging the recumbent configuration, which is ity to move around on the bike seems able — even though it did not have arm only 4% heavier, is 7.7% slower (with to generate more power for at least a test results summarized in Bicycling via chain, idlers and freewheel to the power motion at all. I could not pro- ride; the one time I rode with a heart- Science. [1] These results showed that bottom bracket chainrings. The chain rate monitor it showed a maximum of arms) and fully 12.2% slower without short period. duce enough torque to control the bike arms. with a “forced rowing” mechanism twists a bit during steering. Gardner merely by gripping the vertical handles. 186 beats per minute. My wife tells me General observations using both arms and legs, “…about 12.5 says that the rider does have to learn to the charts show that at my age (47) I should note that the times shown The quick addition of horizontal exten- in table 2 were taken early in the devel- How does it feel to ride? Good. Even percent more power than with normal counter some of the torques introduced sion handles (bar ends) to each vertical that should have killed me! Table 1 when you are using a great deal of pedaling was obtained throughout the by arm power, and indicates that the shows the times for three parts of the opment of the arm power recumbent. handle produced an easily-controlled Perhaps additional conditioning would force to push and pull — you can use time period for all subjects.” Forced arm-powered bike lets a rider produce bike — but it was now much wider than ride — in certain cases I did not com- both strokes for power — you are still rowing is a mechanism that defines the more power, and use higher gears on plete the ride, or did not get a time for make a difference. I desired. Finally, I also compared my heart able to make fine steering adjustments. end of the stroke and thus conserves hills, for example. Gardner’s ergometer The next (and present) prototype the final part (stopwatch error!). Apparently your body is well attuned the kinetic energy of the moving mass- tests showed a higher heart rate as The comparisons are only rough. As rate with and without arm power on a involved modification of my bike’s trainer. I used my old Houdaille “Road to controlling small differences in the es. This is unlike typical rowing in a soon as the rider starts using his/her- existing handlebar clamp/bearing unit table 1 indicates, I used a Brompton motion of your arms, even when they boat, where the rowers must decelerate arms, so it may be that the arm-and- folding bicycle as the upright. The Machine” trainer: this trainer uses (see fig. 3) and the addition of the hori- a flywheel/fan to provide both wind are moving quite a bit. and reverse their motions without help leg-power combination is less efficient zontal axle, held by bearings placed in Brompton has 16-inch wheels and a One thing you cannot do is ride one from the mechanism. [2] than a legs-only machine. My tests, five-speed hub, so may be less efficient resistance and realistic simulation of modified handlebar clamps. I first tried the momentum of the bike and rider. handed — or, you can, but only if you While the result showing additional however, do not show this result, as I the bike without the arm-power con- than the recumbent. Then again, the stop pedaling. If you stop pedaling, you power available from the arm and leg describe below. Brompton has high-pressure (85 lbs) I established a steady speed (as mea- necting link — the handlebars worked sured by a typical cycle-computer) and can use your feet to hold the power power mechanism is indeed intriguing, fine for steering — and then hooked up tires, and has a weight advantage over mechanism steady. Then pushing or it should be noted that the test period Development my recumbent — 12.3 kg (27 lbs) versus noticed that my heart rate was stable at I gave active thought to adding arm the arm power link. As I said, it was that speed (within about plus or minus pulling on one handlebar gives you extended only as long as five minutes. surprisingly easy to ride. 15.5 kg (34 lbs). conventional steering. But steering With respect to creating arm and power to my recumbent for at least five While I came close on the upright in 1 beat per minute). I then stopped years, and ran through many possibili- Over the next several months nearly using my arms, and used my legs with one hand while the handlebar also leg power mechanisms for human all the components were replaced as one case (trial 4 compared to trial 1) moves back and forth with the pedals powered vehicles, references on the ties in my mind. First, however, I need- nevertheless, the best times went to the alone to maintain that speed. At every ed someone who could help with proto- they either broke or proved too flex- speed-heart rate combination that I is nearly impossible. This is a serious internet indicate that there has been ible. Also, I did not feel that my arms arm-powered recumbent. Without drawback that I shall try to fix, as I quite a bit of activity. (See, for exam- type work. A short search of local bike tried — from a sedate 12 miles per hour shops turned up Stephan Long. He built were making an adequate contribution describe in “Future developments,” ple, www.geocities.com/rcgilmore3/ to powering the bike — my legs would below. a stationary bike/trainer that included Table 1. Times for uphill ride (min:sec) land_rowers.htm.) I’m aware of only As I mentioned earlier, there is no handlebars much like those on the bike feel fatigued while my arms didn’t seem Trial Bike Part 1 Part 2 Part 3 1+2 1+2+3 two bikes currently in production: the to be doing much work. So I experi- freewheel between the pedals and the Thys “Rowingbike” is built in the Neth- described in this article, linked to the 1. Recumbent - with arms 05:06 14:07 11:17 19:13 30:30 mented with different ratios between 2. Recumbent - no arms 05:37 15:43 12:41 21:20 34:01 arms, so that your foot motion carries erlands (see www.rowingbike.com); crank chainwheels in much the same way. I didn’t do any scientific tests, but the arms and legs. The original ratio 3. Recumbent - with arms 05:15 13:45 11:12 19:00 30:12 your arms through the dead spots at Scott Olson’s “Rowbike” is built in the was 2:1 — the arms going half the speed 4. Upright - Brompton 04:58 14:16 — 19:14 — the end of each stroke. In fact, it is USA (see www.rowbike.com). These it was clear that the mechanism was comfortable to operate, and appeared of the legs. I then tried a 1.5:1 ratio. 5. Upright - Brompton 05:23 14:42 12:15 20:05 32:20 almost impossible to use arm power bikes use a “free rowing” motion (as While this sounds odd, it was still com- 6. Upright - Brompton 05:24 14:23 — 19:47 — only — you tend to get stuck at one end
8 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 9 of the stroke or the other, or else you Finally, I have not yet decided wheth- [2] The ergometer tests were conducted approached the bend his cycle comput- This proportion had been 45% in 1989. fee” basis: that is, she/he will charge push or pull a moment too soon — and er to patent the arm power mechanism. by J.Y. Harrison, and reported in er was registering about 75 km/h and Popular opinion also paints a picture the client nothing for his/her services, end up freewheeling backwards. My understanding is that U.S. law “Maximizing human power output that Bill was out of sight ahead of him. of a flood of products-liability litiga- but will take 25–33% of any monetary I worried about play in the mecha- allows me to file within one year of the by suitable selection of motion cycle He braked to get around the bend and tion. In fact, products-liability lawsuits award. This has the socially desirable nism between the arms and the pedals. disclosure marked by this publication and load,” Human Factors 12:3, saw that Bill had hit a stone wall and were less than 1 percent of the total consequence that people of limited I worried about wrist strain, since the (while I have now forfeited European 1970, pp. 315–329. was lying on his back some distance state and federal caseload in 1994 [1] wealth are given full access to the pivoting handlebars would appear to rights). No one that I have consulted from his bicycle. and less than 0.4% of the civil cases courts in cases where they have been The author move your wrists in a way that nature who has expertise in this area, how- Bill had severed his spinal cord and in state courts. (There is a huge back- harmed. Although occasional large did not intend. So far, however, that ever, has recommended pursuing a pat- Dan Kirschner
10 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 11 and just launched on a promising that the sheave/rope diameter ratio “straddle” cable broke. When I exam- ment, no company was interested in edly resulted. career, is permanently confined should be 72 for long life, with 42 ined the rear brake I found that it, too, the brake. After a long period there This problem, and an investigation to a wheelchair because the fork being an absolute minimum. At a had a frayed “straddle” cable and that was a fairly sudden switch to alumi- into it, are described in appendix III. of a new bicycle snapped in nor- ratio of 7, the rope was bound to it, too, was about to break. This horri- num rims. These do give much-bet- It was found that a seriously unstable mal use. No amount of money have a very short life before metal fied me, because the next trip taken by ter wet-braking performance than do tire (when flat) could be converted could compensate this person and fatigue caused it to fail without my wife would almost certainly have steel rims. Unfortunately, they also to one that gave stable, controllable her/his spouse and family for the warning. When the lawyers for been downhill with our small daughter wear very rapidly and are then liable conditions simply by improving the fit terrible change in the quality of the two sides agreed on an out-of- in a child seat, and the cable would to explode without warning under the between the tire and the wheel bead- their lives for perhaps the next court settlement, I became very have certainly failed when she tried to high forces produced by tire pressures. seat (fig. 5). Further, we found that in fifty years. The medical-care costs disturbed that workers would stop at the major intersection at the When the front-wheel rim explodes, the the U.S., Japanese, and International alone could amount to a huge sum. be killed or injured because, it bottom of the hill. wheel is likely to lock up suddenly, and standards (ISO) there were standards Such cases could be regarded as the Figure 1. Cantilever brake showing cable seemed, the information about the On examination, I found that the very serious injuries can result to the for rim diameters but there was none norm in malpractice lawsuits against clamped to the top of left cantilever, extreme hazard that these ladders and straddle cable was attached to the rider [7]. for tire beads. the U.S. medical profession, which and typical angle through which the booms posed would not be made pub- right cantilever-brake arm by a pivoting This defect is similar to the first, In my editorial for Human Power 51 takes extraordinary steps to prove that cable bends at each operation of the lic. The attorneys agreed with me that brake. joint, where there was no sign of incipi- above, in that the failures do not occur under the heading “Tiresome” [8], I con- every decision and procedure taken has my professional-engineering ethics out- ent failure, but it was bolted to the until the bicycle has been ridden for trasted the public concern over the tire been for the best. A whole battery of weighed my expert-witness responsibili- top of the left arm (fig. 1). The angle some time. Most bicycles sold in the failure that caused the fatal crash of Figure 2. Curved washer very expensive tests will often be speci- ties, and allowed me to send warnings through which the average cantilever U.S. nowadays are ridden relatively the Concorde airliner and over the tire (above) made to fit fied for a minor ailment, purely to ward of the extreme danger of these ladders under the clamp bolt brake rotates guarantees that the cable little. Serious adult bicyclists (I am failures on Ford sports-utility vehicles off a suit against supposed malpractice on the cantilever arm, to unions and other places. However, I will fail in fatigue, just as surely as will one!) are the people who bear the with the total lack of concern over the in the event that a patient’s recovery providing a large-radius believe that the manufacturer recalled a paper clip that is bent back and forth. brunt of these fatigue failures in cables, performance of bicycle tires, causing, is not all that might be expected. A bend for the cable. the trucks faster than did any actions I put on a website an account of this handlebars and cranks, and in the wear possibly, a similar loss of life. “Rem- bicycle manufacturer does not need to resulting from my warnings: the com- failure, something about the design of of aluminum rims. We are, alas, of little edies for bicyclists have the same sta- go to these extremes. However, she/he pany did not want to face the rash of the brake, and details of a very-low- concern to most bicycle manufacturers, tus as so-called ‘orphan drugs’. These must likewise take very conscientiously, lawsuits that it now knew would be cost addition that would give virtually or to government regulators. drugs are not developed for fatal but and document in some way, the design certain to come. Liability litigation had infinite life to the cable (fig. 2, 3), and I Dangerous run-flat relatively rare diseases because drug and manufacture of any component worked! also sent it to the manufacturers. This performance of bicycle tires companies see insufficient profit. Is the the failure of which could cause, with Does it work for bicycle design and account is given here as appendix I. When a bicycle tire/tube deflates, the bicycle-tire-rim case a situation where reasonable probability, serious injury or manufacture, or do we need more-strin- Brake and wheel-rim failures tire either provides directional stability industry is not being sued enough? death. gent government standards? Below I When I started bicycling most brakes or, more likely, produces such instabil- The much-maligned product-liability Manufacturers in countries where discuss three areas in which I believe acted on the wheel rims, and most rims ity (through “flopping” from one side to lawyers can correct serious deficien- liability litigation is rare might well that bicycle manufacturers have not were steel. Braking was adequate in the other, fig. 4) that the bicycle rider is cies in industry responses, or lack of react with some alarm at having to take been as diligent as is required by the dry conditions, but appallingly inad- thrown off. This is particularly the case responses, to shoddy practice.” major precautions to avoid being sued, need to protect the public. equate when wet. When we studied the if the tire is on the front wheel. Many My sad conclusion from these three and to face unwelcome prying into their Three examples of problem, we found that the then-avail- injuries and some deaths have undoubt- areas is that bicycle and component design, manufacturing and business avoidable defects in bicycles able brake-pad materials suffered a manufacturers do not exercise the practices if they are sued. These risks drop of well over 90% of their friction highest engineering capabilities in Fatigue failures in cables seem to be the price we pay to have coefficient when wet. [5] We also found bicycle design, and that improvements The parallel for our industry to the markedly safer products in the U.S. an aircraft-brake-pad material that had are needed. wire-rope failures in the aerial-ladder (and increasingly the safety advances almost the same coefficient of friction Figure 3. Cantilever brake with curved case is that bicycle brake and gear- Impact of liability laws achieved in the U.S. have been adopted wet and dry. However, the level was washer installed, showing gentle curve shift cables are taken around pulleys on bicycle design in Europe and elsewhere. The European through which the cable is now bent. too low for direct substitution in the and bends with a diameter ratio of far Commission has in fact recently pub- caliper brakes of the time. A simple The perceived impact of liability less than 42, and also fail periodically lished “The Green Paper” recommend- increase of leverage to give a greater laws in the late 1970s on the design without, usually, any warning. I have ing changes substantially in the direc- I believe that the message does get braking force was also impracticable, of the Avatar 2000 which we believed had many cables (and handlebars and tion of U.S. practice. [4]) broadcast. because such a brake would not give Figure 4. Tire with beads having slipped to be the first recumbent bicycle to cranks) break suddenly, but fortuitously I believe that the quality of design the clearance needed for free-running off the bead set flops over first on one be produced for general sale since A sample case: never at a critical time. If I had, there and manufacture is enhanced by the of naturally “wobbling” rims. We then side, and then on the other. the 1930s, was the following. The fatigue in wire ropes would have been a strong probability possibility of liability litigation. There devised and patented a brake mecha- initial impetus for the design was my An example is a case in which I of a fatal accident, and, because bicycle is, however, some question about the nism that had two sequential leverages: concern for safety, [9] because I had served as an expert witness. A lines- accidents are usually not investigated benefits that occur if a case is settled a low leverage that would bring the seen many reports of riders of regular man working on overhead wires while with any degree of seriousness, the out of court, because of the secrecy pads up to the wheel rims with little “road” bicycles being severely injured on a truck-mounted aerial ladder was cause would not have become known. that is more marked in the U.S. than in, movement of the hand-brake lever, and or killed after going head-first over severely injured when the ladder sud- A recent example illustrates the prob- at least, Britain. (My professional field then a high leverage that produced the the handlebars on applying the front denly collapsed, dropping him to the lem: I normally ride recumbent bicycles. is turbine design, and the catastrophic required braking force. We demonstrat- brakes too hard, or riding into a grat- pavement. The cause was relevant to However, when snow or ice covers the failure of a turbine in Britain is followed ed the brake’s outstanding performance ing or hole in the pavement, or having safety in bicycles: the ladder was oper- roads I switch to an “upright” bicycle, by a full exposure of the causes, and to many U.S., Japanese and European baggage or a stick get caught in the ated by wire ropes that passed around and on such a day recently I borrowed the steps taken to cure the problem, in companies, and lent them prototypes. front wheel, for examples. It seemed several sheaves (pulleys). my wife’s town bike to go to work. We papers presented to the Institution of A description is included in appendix to me to be safer to go feet first. It was The sheave diameter was only seven live on a steep hill, and I needed to ride Mechanical Engineers.) This public air- II, derived from an article published in Figure 5. Tire with beads retained on the easy to list, in addition, other virtues times the wire diameter. The standards up it. I applied the brakes gently to ing seldom occurs in the U.S., except Velo Vision [6]. rim bead seats runs symmetrically, that would improve safety: the near- set by the wire-rope manufacturers are get ready to mount the bike. The front in the case of airline crashes. However, To our consternation and disappoint- giving good controllability. impossibility of catching one’s pedals
12 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 13 on the road; the great improvement in making a profit themselves. Insurers did think of this possibility, but were those on motor vehicles, and so forth. by the manufacturers to individuals automatically switch over to a high the ability of the rider to see forward have a major stake in litigation, and overruled. One obvious conclusion is There are several ways (research and and to bicycle-repair shops, who mechanical advantage. In other words, and to the side; the improved braking have an obligation to ensure that any that no one was concerned about being development, industry standards and should be paid for getting in touch with once the pads hit the rim, instead of capability on both wheels; the shorter settlement is not greater than the limits sued for malpractice. Yet it is surely government regulation being three) owners and for installing the washers a hand movement on the brake lever reaction time resulting from the hands of the insurance that has been pur- malpractice to design and install a whereby improvements in bicycles can and replacement cables. (I donate the moving the brake pads rapidly and with being on or close to the brake levers chased by the manufacturer. An insurer device that, although it works wonder- be attained. We may have to depend on design for this purpose.) That a washer little force, further hand movement at all times; and the lessening of inju- (meaning an individual agent or the fully for every expected use, will kill a fourth way: liability litigation. of this type (a slightly different design would move them just a small distance, ries because riders are closer to the firm she or he represents) may decide or injure in an unexpected, but not would be required for each type of but with massively more force. This Acknowledgments ground than when on road bikes. There to settle out of court even though many unlikely, situation. brake) completely solves the cable- system would produce a sufficiently were, and are, a few negative aspects may believe the case to be defensible, Attorneys Neil Sugarman and Phillip bending problem can be seen from fig- forceful squeeze to take advantage of Can concern for safety go too far? to recumbents: the view to the rear is as in the example quoted above, simply M. Davis and my spouse Ellen Wilson ure 7, showing the modified brake (in the new material, but still give plenty of more circumscribed unless one uses to avoid the continuing high costs of Designs analogous to heat-sensitive were kind enough to read early drafts the “brake-on” position) on a Special- clearance between pads and rim when a rearview mirror; and it is difficult attorneys and expert witnesses and the buttons for elevators can be found in of this paper and to give valuable ized bicycle. the brakes were “off”. John Malarkey to recover from a skid because of the large amount of time that its own per- many areas. Only a few years ago we advice and documents that I have worked on a nice design to do this Appendix II: The Positech Brake low center of gravity and the attendant sonnel will be spending on defending drove cars that had rigid steering col- incorporated in the final version. using hydraulic brakes. However, we umns ready to pierce drivers’ chests (Excerpt from: “The Brake That Got rapidity with which one is “dumped” the suit. Appendix I: Serious, inevitable fail- found that it had previously been pat- on the ground. The “safety balance” even in a low-speed collision. Now Away: The Positech mechanism was all ented for automobiles. Brian Hanson, Education and litigation ure on Shimano cantilever brakes is clearly in favor of the recumbent. we have cars in which the driver and set to revolutionise cycle braking—but for his bachelor’s thesis, measured Design education has been helped occupants are surrounded by air bags The brake cable on several types it never happened”). [6] However, we knew that we would not (e.g., BR-CT20) of Shimano cantilever more precisely the friction behaviour receive large cheques from grateful rid- by liability litigation. At M.I.T., and and restrained by belts and protected In the 1960s…brake blocks were of of the new material, and subsequently, I’m sure at most universities, concern by a passenger compartment that will bicycle brakes (and possibly those of black or red rubber, sometimes incor- ers who felt that our bicycles had saved some other manufacturers) will inevi- for his master’s thesis, worked with me them from serious injury. We would about the impact of litigation on engi- allow people to walk away from a porating fibres. Braking in dry weather on a mechanical braking system. He neering has led to an much-increased frontal collision at 60 km/h and higher. tably fail after a period of use. Brakes was superb, but in wet weather it was be more likely to be sued for larger of this type have at least one of the achieved his objective: the innovative amounts in those few areas in which emphasis on engineering ethics and Some research has found that some abysmal and extremely dangerous. This brake worked, although appearing, as on our responsibilities to society. drivers like to operate their vehicles at stranded brake cables bolted to the seemed to me, a mechanical engineer, our design might be worse than that of ends of the brake arms (fig. 1). one would expect from an academic upright bicycles. The disaster to the Challenger space an exciting level, a level at which they a crazy state of affairs. I put the topic project, rather ‘clunky’. MIT wasn’t shuttle was a shock that brought about perceive a certain degree of danger. Therefore, when the brake is oper- of wet-weather braking on my project We responded to this dilemma in ated, the cable is bent sharply at the interested in patenting it, and we did so three ways: changes, particularly after it was found Give them seat belts and airbags and list for students at MIT in around 1968, ourselves…. that engineers who had been fighting their average speed increases so that point of attachment and then bent back and that year the first of three excellent 1. We made the bicycle as safe as as the brake is released. This process Allen Armstrong of Positech pro- practicable; to have the launch put off because of they feel the same degree of safety or students chose to work on the prob- duced a beautiful new design of our what seemed to them obvious flaws in danger. On the other hand, there is is absolutely certain to fail the brake lem. David Asbell measured the coef- 2. We gave prolific warnings about cable after a certain number of brake double-leverage brake (fig. 6). He kept possibilities of danger; and the low-temperature performance of in the U.S. at present an enthusiasm ficients of friction of commercial brake the same locking-slider system for some seals had been overruled by pol- for huge sports-utility vehicles, partly applications, just as the wire of a paper blocks on chromed-steel bicycle rims 3. We took out an insurance policy clip will fail after a small number of changing to the higher leverage, but he that was standard for (small?) bicycle icy-makers, some of whom were also because they are much more likely to in wet and dry conditions, and found added a feature to decrease the lever- engineers. Our students are shown a survive, along with their drivers and times being bent back and forth. This is that the standard black-rubber block manufacturers. a very serious danger. age during the pad-approach stage of We discussed the positive and nega- videotape of a talk by one of the “whis- passengers, in collisions with regular suffered a loss of well over 90% of its the braking action.... tle-blowing” engineers involved in the automobiles. The safety of others, Widespread standards for strand- friction capability when wet — clearly tive features of the bicycle design with ed-steel-wire cables (e.g., as given I also demonstrated the brake fitted the insurance representative, who felt Challenger case, and many are moved including pedestrians and riders of unacceptable for a road vehicle’s main to the front wheel of a Raleigh Gran to tears. We examine other case-studies bicycles, has thereby decreased. There in Marks’ Standard Handbook for braking system. He also tested some comfortable in giving Fomac, manu- Mechanical Engineers, 7th. edition, Sport with steel rims (standard at the facturers of the Avatar, a policy that for lessons to be learned. For instance, is, therefore, an optimum level of safety automotive friction materials, and time) to Raleigh management at their one of the first skyscraper fires in his- engineering. This level should be found McGraw-Hill, 1958, p. 8–114) give found one that had only one-quarter of would apply to manufacturers of regu- the minimum diameter of drums or US headquarters in Boston. I could lar bicycles. There was an indication tory occurred in a New York building by estimating the benefit-cost ratio of the dry friction that rubber could gen- show exactly the same emergency stop- on the 37th floor, far too high to be any proposed change, evaluated over “treads” around which a cable should erate — but about three times the wet that, if the Avatar turned out to be as be bent as 72 times that of the cable ping distance with the wheel wet as much of an improvement in safety as reached by ladders. The first group of the whole affected population, not just friction. We later found a material used when it was dry. firemen decided to take the elevator to the users of the new system. [10] The diameter, with 42 as an absolute in aircraft brake pads that also had we claimed, our rates might even be minimum “in certain cases.” A bicycle The brake had additional advantages: reduced. This gave an added incentive, the 38th floor, break through the ceiling “benefit” side of such analyses require about a quarter of the black-rubber dry it was self-adjusting, and the pads and spray water on the fire. However, the invidious decision on what value to brake cable is typically about 1.8 mm friction, but virtually identical friction if one was needed, to increase safety (0.07") diameter. Therefore the radius seemed to last for ever: over two years in our design wherever possible. As the elevator stopped on the 37th floor, put on human lives saved. Perhaps it performance wet or dry. The following for me — at a time when I was bicycling the doors opened automatically, and is justifiable to avoid this thorny ques- of a curve through which the cable year, two students enlisted to work on mentioned above, insurance rates for should be forced to bend should be at over 15,000km per year. It required no liability have in fact dropped markedly all were killed. The elevator was one tion by using, instead, the expenditures the topic, and we discussed how we modifications to the bike or the brake of the first to be operated by heat- that could be predicted as having been least 38 mm (1.5"). The incorporation could use the ‘new’ material. We could since that time. of a sharp bend for the cable in these lever. It could be made much lighter sensitive buttons, and these naturally avoided in litigation lawsuits. In either not simply increase the leverage of the than was our prototype. We thought The insurance industry designs of brakes, relied upon by bicy- stopped it where the fire was blazing. case, benefit-cost analyses would brake operating mechanism, because that the brake would be irresistible. All Insurers are therefore major players We ask our students how it was that indicate that some proposed safety clists to save their lives at intersections then the pads would move only a quar- and down hills, betrays a shocking the companies that carried out tests in liability litigation, frequently almost in the several years required to invent, measures had gone too far. It is also ter as far. Bicycle wheels cannot be obtained the same or better results. taking the place of the defendants in develop and manufacture this elevator- certain that safety aspects of bicycles, ignorance of standard practice. produced and maintained ‘true’ enough Steps that need to be taken ...but not a single company wanted pretrial organization of the defense control system, no one in the company regular and recumbent, would be found to have a pad such a short distance to take out a license to manufacture and in the trial itself. Their role is that making them, nor in the architectural to have not received enough attention. These brakes and cables should be from the rim without it rubbing. We recalled and replaced on an emergency them.... of insuring against risks to businesses, engineering offices specifying the use We cheerfully ride bicycles with brakes then hit on the breakthrough concept: I even visited the Raleigh head- and of doing it in a way that is least of the buttons, ever considered what that wear fast and don’t stop us safely, basis, either voluntarily by the manu- a mechanism that would bring the pads facturers or by government mandate. quarters in Nottingham, UK, and was costly to manufacturers (otherwise would happen in the case of a fire. It on rims and tires that can explode at at rapidly up to the rim, moving with little entertained to an impressive lunch in they would go to other insurers) while seems likely that one or more people least a thousand times the frequency of As a low-cost alternative, curved exten- force, and then when they hit the rim, sion washers (fig. 2) could be supplied the panelled boardroom with the senior
14 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 15 protective barrel. A relatively Further pulling on the lever causes the tire blowouts, or at least rapid loss of weak coil spring pushes the brake to rotate on its pivot (unseen) so pressure, that have resulted in my hav- slider to the top of this tube. that the ‘R’ arm also contacts the rim. ing been thrown off my bicycle with When the brake lever on the Further pulling of the brake cable can’t some violence. One was when riding a handlebar is pulled, at first move the slider further, so it now over- Moulton road bike as a bus was about it does not overcome the comes the torsional spring on the ‘R’ to pass; one was on an Avatar 2000 torsional spring, so that the arm, and presses the blocks to the rim recumbent; and one on a new German brake cable does not pull up with the large force represented by the Viento recumbent, when I narrowly on the ‘R’ arm. Instead, the distance ‘r’. In use one does not notice avoided being hit by a large truck. A slider is moved down over any of these actions: the brake seems friend told me about someone who the tube, and the link pushes to operate with a smooth motion that was, in fact, killed after his front tire the ‘L’ arm quickly against the gives almost instant braking even with burst, causing him to be propelled into rim with a low force level, large gaps between the pads and rim. the path of a car. because of the small lever-age It thus automatically compensates for The reporting from dead bicyclists represented by the distance ‘l’. pad wear. is zero, and the reporting of and APPENDIX III: BICYCLE STABILITY examination of bicycle accidents are so Figure 6. (Left) Allen AFTER FRONT-TIRE DEFLATION perfunctory that it is highly probable Amstrong’s “Positech” brake. that a considerable number of deaths Figure 7. (Below) How the The problem and serious injuries are the result of Positech brake works. On three occasions I have had front- instability following front-tire deflation. Therefore this has to be regarded as a serious problem. Our study of the problem In the summer of 1998 I wrote about flat-tire instability to an e-mail list then called HBS, for “Hardcore bicycle science”. No one reported previous studies of this problem apart from one described by Doug Milliken, who wrote a letter “Flat-tire directional per- formance” to Human Power in spring 1991 (9:1, p. 17). He tested a motor- cycle fitted with proprietary run-flat tires on the rear wheel. The tires had a flap of rubber on the outside of the tire that fitted tightly over the rim and acted as a bead-retention system. One with a small flap did not in fact hold the bead when the tire was flat, and the bead fell into the “well” in the rim. The tire flopped around, causing the motor- bike to go unstable, even though the tire was on the rear wheel. The second tire with a wider flap held the beads in place. With this tire, Milliken found that people in the company. None still rode up pieces of grit, which cut grooves rim brakes heat the rims in long high- he could run the bike at high speed a bicycle, and no one wanted to discuss around the rims. The rider has no indi- speed descents, and the heat can burst (80 km/h) and could perform vari- our brake. Someone stated that they cation of how much wear has taken or deflate tyres, which, on the front ous maneuvers without problem. He were working on another solution to place until the rim explodes under the wheel, can lead to nasty injuries. There thought that good run-flat bicycle tires the wet-braking problem.... huge sideways force of the tyre pres- is a brake now that avoids tyre bursts, would probably be tubeless. Within a few months the new solu- sure. A rim exploding on the rear wheel rim explosions, and lost wet-weather I also wrote to other e-mail lists, and tion was revealed: the whole bicycle just stops the bike unexpectedly. When braking: the disk brake. several writers contributed valuable industry switched to using aluminium- it happens on the front wheel it can How the Positech brake works experiences and suggestions. Some alloy rims. They are much better than be fatal. How can this be a good solu- The left-hand arm ‘L’ pivots around reported similar occurrences to mine, steel rims in wet weather. They provide tion?... A, and the right-hand arm ‘R’ around including Dave Larrington of the Brit- a reasonable solution for people who While I sometimes yearn for the days B. This ‘R’ arm has a strong torsional ish Human Power Club, who had had will travel less than 2000 km on their when I used a steel rim and a Positech spring holding it open against a stop “instant crashes” from front-tire flats bicycles. Those of us who use a bicycle brake on the front wheel with almost (fig. 7; neither the spring nor the stop on regular bikes and on recumbents, for everyday use are less well served by no concern about any aspect of stop- can be seen). The chain link on the ‘L’ and Joshua Putnam, who considered aluminium rims. The braking surface ping ability, wet or dry, I must confess arm is attached to a slider which moves the problem serious enough to institute wears very fast. Also, the pads pick that there was always one worry. All up and down a steel tube inside the the practice of letting the air complete-
16 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 17 ly out of the front tire when trying out in the event of a front-tire blowout. instability that made staying on the March, reported in a leaflet “Myths the remaining few rickshaw men were a new bike. Bill Volk wrote, “I too find However, Doug Milliken, a long-time three bikes mentioned above absolutely The tender independent feelings of and facts about product-liability law- becoming so aged and decrepit that the situation to be unacceptable. I run consultant to Alex Moulton, wrote that impossible. water molecules suits.” even the most crass tourists must have heavy, inefficient thorn tubes because Moulton controls both the rim diameter The tires that caused me the prob- George Tatum, 17 Jan 2002 [3] Rustad, Michael and Thomas Koenig. balked at asking the old man to pull of my fear that a blow out at high speed and the bead size of his 17" tires. lems were exceedingly loose. This [Editor’s note: George Tatum started 1993. “The historical continuity of them along. would be a disaster. Why can’t we have In September 1998 I added the prob- characteristic made puncture repair a company manufacturing fast human- punitive damages awards: reforming The first random thought is about the rims that retain the tires even at no lem statement on flat-tire stability to my almost a pleasure, because one could powered boats, which he also races the tort reformers”. The American often invoked issue of colonial exploita- inflation? And perhaps a rubber strip list of undergraduate-thesis topics at get the tires on and off without tire himself. He has started an ambitious Law Review, 42:4. tion. The supposed indignity of this type that is placed around the rim, under the MIT. Andy Oury, then a senior, respond- levers. They were so loose, in fact, that testing and measuring program and [4] This, and other information quoted of labour, the ‘poor rickshaw man’, a tube, that supports the bike on loss of ed enthusiastically, carried out several centering them during subsequent infla- shares his data freely with others and here, was obtained from a “google” martyr to imperialism, etc. Well, yes, I air pressure…. I had Performance semi- valuable experiments, and has allowed tion became difficult: it was easy to we will eventually share it with you. In search on “Product-liability litigation” guess so, but of course they were just slick 26" tires that fit so snugly that me to report some of his results here. produce an eccentric rolling surface, the meantime, we offer you George’s on the worldwide web, and is diffi- employees of Chinese businessmen you could safely ride no-inflation. That We drew up a too-ambitious program even to the extent of having the tube textual cartoon on boundary layer theo- cult to reference because sources are who owned the rickshaws — rickshaw should be the standard.” in which we wanted to look not only at pop out between tire and rim where ry and hull design:] often not given. magnates, just as taxi drivers today Presumably because of a tight-fitting bead retention but also at the effect of the tire was “high”. Oury built up the First of all, water will not compress. [5] Whitt, F.R. and D. G. Wilson 1982. don’t own the cabs they drive. But is it tire, Ed Deaton of Fools Crow Cycles, the ratio of tire width to rim width (ATB rim shoulders using standard “masking” Also, it will not expand. If forced into a “Bicycling science”, second edition, really an undignified job or service for a faced with difficult choices, rode 8 km tires in particular are usually bulbous, tape, and he put on fifteen layers before vacuum situation, water will get angry The MIT Press, Cambridge MA. fit person to perform? on a flat front tire: he had IRC “Road- having a pear-shaped cross-section on the tires were retained and the flat-tire and boil. [6] Wilson, D.G. 2001. “The brake that The last four machines are up for sale lites” with Sun M14 rims. Similarly Andy what seems like a small rim) and of tire- flopping was inhibited. His experiments Water is made up of molecules that got away,” Velo Vision, issue 3, at about US$1’500! Milstein of Princeton had no trouble sidewall stiffness. Andy Oury worked therefore did a great deal to confirm the readily attach themselves to a hull September, York, UK. Across the mouth of the Pearl River riding with a flat front tire. It was a on what the correspondents just quoted premise: that a slack fit between tire shape. These molecules will build up a [7] Juden, Chris. 1997. “How thin may in Macau a few pedicabs remain. These Tioga Comp Pool, measured by Mark B. thought was the most important factor, bead and wheel rim is the prime cause film which lubricates the hull of a boat. the braking rim of my wheel get?”, a vehicles are much more up my street, of Wheel Life Cycles to be 46 mm wide, bead retention. of flat-tire instability and that a tight This is very helpful. technical note in Human Power 13:1. and in the 20-odd years I have been on a Sun CR-18 20 × 1.75" rim of about fit will therefore provide a substantial At the same time, water hates to be The experiments [8] Wilson, Dave. 2000. “Tiresome”, an visiting Macau I’ve often used them and 27-mm width. (That was significant degree of safety in the event of a front- forced into a change of direction unless editorial in Human Power 51, p. 23. never felt exploitative at all. because one of my early suspicions, We first thought that we could do a tire blowout. [11] it is moving on its own in rhythm or [9] Wilson, D.G., Richard Forrestall, and However in the past 5+ years their and a concern of Larry Black, was that highly controlled experiment by having His tentative results were borne out waves, kind of like dancing with a fat Derek Henden 1984. “Evolution of situation has deteriorated to almost a wide tire on a narrow rim might have my troublesome bicycle wheel and tire, by Soohyun Park, who subsequently girl. recumbent bicycles and the design of the same level as the rickshaw and I a greater tendency to “flop” alternately held in a frame, running on the surface performed more careful experiments The reason water behaves like this the Avatar Bluebell.” Warrendale, PA: doubt if anyone uses them as everyday left and right. This suspicion was thus of an inverted portable belt sander. in which the test bicycle was loaded is molecular. Water molecules love to SAE paper 840021. transport as was the norm until, as I shown to be unfounded.) However, the tire did not display the in various ways to simulate the load- help hull shapes move along, but hate [10] Wilson, D.G. and Joan G. Moore say quite recently. Last time I went to Bill Volk mentioned that Sutherland’s extraordinary alternating flops, left and ing on bicycle tires, and in which she to share or be crowded. When a hull 1971. “Transportation resource allo- Macau a few weeks ago I was shocked Handbook for Bicycle Mechanics had right (fig. 4), that had thrown me off my (and I) successively built up the rim meets a water molecule, the best thing cation based on new methods of acci- by the growth not so much of cars, a good section on fits between differ- bike, and that had prevented me even bead shoulder using fiberglass resin it can do is, as subtly as possible, sug- dent reporting.” Accident Analysis as of scooters. It seems every person ent brands of rims and tires, but my from pushing the bike subsequently until a tight fit of the tire beads was gest to the water molecule to gently and Prevention, vol. 3, pp. 121–138, between 16 and 30 has one. I was edition did not have this section, and (fig. 5). Oury found that, for the flop- obtained [12]. The improvement in tire move back, like a dance step. The mol- Pergamon Press, NY. cycling of course, and found them much I could not get an answer to my letter ping behavior to occur, he had to rig up stability and front-wheel tracking was ecule wants to cooperate. But the water [11] Oury, Andrew P. 1999. “Run-flat per- harder to deal with than cars as they to Sutherland asking about standards a bike to run along a simulated road- dramatic. molecule cannot fit in between her formance of bicycle tires and rims” come up on the inside as you’re trying of fit. John Allen, prominent bicycle way with a similar number of degrees girlfriends which are under her, in front Recommendations Thesis B.S.M.E., M.I.T., Cambridge to maintain a road position in relation expert and author, sent me a copy of his of freedom as has a bicycle when it is of her, or beside her. The only thing she MA. to the cars! Japanese Industrial Standards D 9421, being ridden (or pushed). The International Standards Organi- can do is jump or push. Jump is bad. [12] Park, Soohyun. 2001. “Run-flat What I want to ask is about pedicabs “Rims for bicycles”, giving a tolerance The simplest way of producing bead zation (ISO) should form a committee Push hard is bad. But push back ever retention on the shoulders of the wheel of tire and rim manufacturers to agree performance of bicycle tires and appearing in the UK in recent years. of ± 3 mm for rim circumference, and so lightly is good. If she pushes gently modified rims,” BSME thesis, MIT, Has anybody got any information on of standard K 6302 “Rubber pneumatic rim after deflation seemed indeed for on standards of rim diameter and shape behind her, the girls in the rear, rise a Cambridge MA. this? tires for bicycles”, which, he pointed them to be a tight fit. I have had tires and of tire-bead diameters so that a little, giving her ample room to slide out —bill telfer out, gave neither tolerances nor dimen- that could be stretched over the wheel tight fit could be relied upon in all cir- and in as she rubs herself along the hull sions of tire beads. (Later, Andy Oury rims only with great difficulty. When cumstances. shape. these were inflated, the tire beads Now, I have moved a lot of water found that the International Standards Author INTERNET GLEANINGS Rise of the pedicabs in remained in the rim “well” until the molecules in my life and I have grown Organization ISO 5775/1 “Standards for Dave Wilson is professor of mechani- the occident tube inflation pressure reached around Demise of the rickshaws in from each. Firstly, if you suggest to a bicycle tires and rims” also had toler- cal engineering, emeritus, Massachu- 80% of normal full pressure. They then the orient From: Andrea Casalotti, 2 Jan 2002 molecule that she move a direction with ances for rim diameters but not, as far setts Institute of Technology, Cambridge In London there are about 80 pedi- “snapped” over the rim shoulders with From: Bill Telfer, 1 Jan 2002 a certain force, keep the force exactly as he could determine, for tire beads). MA USA; e-mail
18 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 19 suck on her friends who are still push- into a sharp point, or a void, you will if you slap a molecule when you meet ing her, and they are apt to trip all over bludgeon molecules you meet, and not her and slap her again when you break themselves. On the surface, this looks only do you get a wave, you could get up with her, you will get the most from like a wave. The same applies to the angry, boiling, cycling water, working her in-between. This works until you withdrawal, but the key is to never let against you in a collective. If you have are really looking for the big coopera- Theo’s mini ice-scooter the molecule know you have changed a flat surface that transitions to another tive hull wave, something bigger than direction. The withdrawal part of the flat surface, you will face an angry mob your hull form itself. hull shape should optimally suggest the of girlfriends. It takes millions of these Don’t even consider building a dia- ast winter we had a few rather cold weeks same type of movement with the same girlfriends to cost you a knot of speed. mond shape. A diamond will slap water without precipitation in Switzerland, force as the intrusive entry part. In fact, But why make war in a sea of love? molecules, in the middle of locomotion, which allowed several small lakes to it is best if the molecule doesn’t even (Hydrofoils float by doing violence to and they will all hate you. L freeze enough for skating. With the mini-scooter realize you’ve come and gone. The more a few. This method may be unbeatable Think subtle, smooth, long, but firm. boom having left its mark here also, it seemed she does, the more wave you make, the in short, hard efforts — but love is mea- Go gentle, but [with] consistent pres- natural to me to fit one out with blades for the slower your progress. sured in distance) sure, and go as light as you can. ice. I had a some spare rather short, strongly If you change the radius of your hull The main hull wave is different from Despite the lack of math in my head, rockered skater’s blades and quickly attached shape’s curve, you will cause the water the hull skin transition waves. The hull I sure have fun. As long as the sea these to my mini-scooter with bits of wood in molecule that meets this change to wave is a happy love memory that you keeps treating me as well as she does, I such a way that the blades were free to rock, have to push back harder, or pull back must figure out how to mount as high will remain hard consistently to beat in i.e. unconstrained in pitch, except for enough harder on those around her. This easily as possible. Hull shape transition waves the human-powered circle. Someday I friction to prevent flopping. could cause molecules to pile up and are independent angry girlfriends drag- will be more sea than human. The ice-scooter worked well from the start fall over, which, as I mentioned before, ging in their heels as you pass them by. — Geo and was pleasant and easy to use. The is a wave. If you run a curve hull shape The prismatic coefficient states that platform was a bit higher than with wheels by the length of the wood screws used for attachment, so I tired faster than Arm-and-leg-powered tricycle on the road. Also, the traction of the pushing foot was insufficient on good ice. I did try mountaineering he picture shows Robert Barnett conventional bicycle cables and pulleys. the hand-cranking mechanism. crampons, which gave excellent of Choctaw, Oklahoma and his Barnett said that it took him four Making it all possible, in addition traction and also perfectly com- amazing arm-and-leg powered X4. years and a lot of prototypes to develop to Barnett’s ingenuity, is his business T pensated for the height differ- (not speed skates). Arm-and-leg powered recumbents, the X4. “This is the 14th model,” he workshop, Barnett’s Tool & Die. The X4 ence. It wasn’t a solution, how- On ordinary white ice a comfort- both two- and three-wheel, aren’t said, referring to the machine depicted design is patented and Barnett is hoping ever, as I could not change legs able long-distance speed was about new — and one, the Angletech Quad- here. to find a manufacturer. He can be con- while on the move and couldn’t 15 km/h (almost 10 mph). On bumpy raped, is available commercially, but The basic trike frame and seat are an tacted at 915 Oak Park Dr., Choctaw OK even ever rest the pushing leg ice it was more comfortable to use they all have required the rider to pivot S&B Speedster (made in California), but 73020, USA. on the platform momentarily. the scooter than skates. I never the hand-cranking mechanism in order Barnett carried out significant modifica- — Submitted by Mike Eliasohn The best solution proved to be found any really perfect ice except to steer. tions to the basic trike, including mak- Robert Barnett provided this photo of his simple walker’s studs, an for very brief stretches, where the What makes the X4 unique is that ing a titanium rear axle, in addtion to hand-and-foot-crank trike. arrangement made of rubber feeling was then very similar to using instead of attaching to pull over your shoes — the wheels on a perfect surface. The the arm-cranking containing about five studs as controllability was as good as with mechanism to the found on tires. This allowed the wheels, quite tight curves being steering fork, Bar- resting and changing legs. easily possible. nett developed a The normal speed was Where the ice-scooter really twisting mechanism similar to using proved ideal was on a frozen creek, to steer it. That is, basic skates where I could go downhill over the plane in which stretches I wouldn’t dare to with the hand cranks skates. Although there was no brake revolve doesn’t (as for the road), the free foot made change, but while a good brake, especially with the pedaling with your walker’s studs, yet more control- hands, all you have lable than trying to brake this way to do is twist your on the road, where friction and shoe wrists to the right or abuse are too high. The mini-ice- left to steer. scooter still folds and can easily be Since the brake carried everywhere, but the bit of levers also have extra weight is quickly felt. However to be attached to it takes only a short time to switch the hand cranks, it back to the wheels, so that this makes the mecha- remains a usable transport solution. nism rather compli- —Theo Schmidt cated. All the link- ages are done via Monika Flückiger Monika
20 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 21 BOOK REVIEWS LETTER of records for HP vehicle classes and HPVA & IHPVA events that did not exist twenty years Backgr ound Because the North American HPVA Von Null auf 140 mit 93 Zähnen: human inter- Commercial velomobiles ago might now be formally acknowl- The original letter below was posted edged, such as: kick scooters, personal continues to produce Human Power, Aerodynamik von Pedalfahrzeugen est stories, the like the Leitra, Go-One, to a listserv for a small audience: the the technical journal for the IHPVA, the by Andreas Pooch writing style Allweder, and Quest are achievement on stationary ergometers, North American hpva-board list. Newly- roller blading, HP hovercraft, ocean latest election of board members for the Liegerad-Datei-Verlag, Troisdorf 2001 is factual with described and pictured. elected board member John Snyder North American organization, as well as www.ligerad.de/aero.htm no personal There is also a description crossings, and other future develop- wrote the message in response to a ments we might not be able to foresee future dialogs with other IHPVA mem- ISBN 3-9806385-2-9 commentary, on how to make a fairing suggestion by another new board mem- ber organizations, will be very impor- 12.65 the focus from closed-cell polyethe- at this time. This may be an IHPVA ber, John W. “Elrey” Stephens, who rather than HPVA matter. tant for the future of this publication. 112 Pages (7 of these are advertising), being on lene (sleeping mat material). suggested, “Before we survey the mem- At the present time, the HPVA con- A5 technical There are some addresses It’s as if there is a mini-dark age of bership, though, how ’bout a survey of stagnation where learning for its own tinues to pay all costs involved with the Reviewed by Theo Schmidt description and references, mainly Ger- the board? What do we want from the sake is temporarily no longer fashion- technical journal: layout services, enve- In spite of it's title (translated Zero and con- man-language and European, HPVA, in return for our effort and our able, and that the sublimely interesting lopes, printing, mailing, storage—and to 140 with 93 teeth: Aerodynamics of struction. “Human-Power” is not refer- dues?” and infinite subject of human power has servicing the four or five single sub - pedalled vehicles), this book is highly One thing enced at all, and the IHPVA — Jean Anderson become muted in academia. Did you scriptions provided. The latter must be readable also by non-aerodynamicists, I learned only briefly mentioned. In spite In r esponse to Elr ey’s suggestion for know, as an example, that according to handled separately, causing extra time not containing much in the way of from a of this, American vehicles and survey of the new boar d of dir ectors David Rodgers, director of the Office of and costs for airmail postage. highly technical material. It is rather a descrip- record-holders are described I continue to be captivated by the ide- Technology Utilization, the U.S. Depart- Delayed for two years, the HPVA copius account of the history of stream- tion fully, drawing on references from als expressed in Article III of the HPVA ment of Energy currently devotes zero recently held an election for seven lined HPVs to the present day, perhaps of the Cycling Science and New Cyclist. by-laws, especially paragraphs b and d resources to the study of human pow - board members (Alan Thwaits resigned the most comprehensive coverage yet SRM This book is a must for Ger- as appear below. ered topics? That is a frightening omis - during 2001). The newly-elected mem- available in the German language. It is power- man-speaking HPV enthusiasts and sion, one that helps clarify the essential bers, most of whom have not held richly illustrated with over 100 small measuring sys- interesting to look at for others as need for this association to continue to office with the HPVA, will determine but clear B&W photos and figures. The tem, is that corrections must be well. ARTI CL E III. PURPO S E S, try filling our unique niche. the direction of the North American vehicles are described chapter by chap- applied for curves, as two-wheelers lean —Theo Schmidt O B JE C TIVE S AND F UN C TI O N S Allow a wild daydream for a moment. organization for the next few years. ter in a vaguely chronological order. and the wheels travel further than the S E C TI O N 3.02 S PE CIF I C Imagine that all of the educational Not much is said about competitions or path the vehicle's center of mass takes. Cover illustration: Andreas Pooch HPVA boar d election r esults PURPO S E S materials produced by the HPVA and (b) Information. The corporation Expir es IHPVA were available in every high Name Dec. E-mail addr ess shall serve as a source of information school and college campus with an ath - Gerry Pease 2002 [email protected] for all human powered land, water John Snyder 2003 JCSnyder.studio@world and air records and all other records letic or science department, in North America. And that regular scientific net.att.net The recumbent bicycle reviewer (who rides every day of the (Not all are attributed and described, pertinent to the pursuit of human power. Jake Fr ee 2003 JFr [email protected] symposiums were once again held that by Gunnar Fehlau; translated from the year) would balk. which would be desirable. I had mixed The corporation shall act as a source John Cooper 2003 [email protected] encouraged meaningful basic research German by Jasmin Fischer Chapter 3 is on racing and speed feelings when I saw, earlier in the book, of technological information on human Paul Pancella 2004 [email protected] to be conducted and made public. Out Your Backdoor Press, records; 4 on aerody- a very bad sketch of mine, and in this powered transportation. John Stephens 2004 [email protected] These might be ways to keep the dream 4686 Meridian Road, Williamston MI namics. case I was glad not to be acknowl - (d) Stimulate competition and Jean Anderson 2004 [email protected] of widespread application of HPV- 48895, USA US$24.00 postpaid edged!) creativity. In all rules, regulations and and, incumbents related technologies fresh and vital. Sean Costin 2002 [email protected] ISBN NO. 1-892590-55-7 There follows the longest executive decisions of the corporation, it shall be the overall philosophy and The knowledge of others’ accomplish- Danny Too 2002 [email protected] ockport.edu Reviewed by Dave Wilson and best chapter (5), “Basics of policy of the corporation to stimulate ments can pass along the all-important Paul Gracey, former HPVA board We owe thanks to Jeff Potter, recumbent design”, in which Gun- and not stifle competition and creativity. but nebulous notions of possibility and member, is the North American repre- well known to IHPVA people, for nar Fehlau applies his wisdom to To this end, the fewer and simpler the hope. Fill out the daydream with the sentative to the IHPVA. becoming a publisher and bring- just about every aspect of different rules, restrictions and regulations, the HPVA’s membership rolls represent- ing us this excellent book. Gun- types of recumbents, complete with Human Power better. ing at least 3,000 souls within the next nar Fehlau is an enthusiast for long lists of advantages and disad- During the past few months, David three years. recumbents, and it shows. vantages of each variation. I have not Gordon Wilson (HPVA), Richard Bal- As long as hope and dreams exist The book starts with a good seen this level of detail and guidance, Meeting the above objectives is lantine (BHPC), and others have been we human-powered humans have noth- history, told with a distinctly and it is excellent. exactly what I want to see happen as a engaged in an e-mail dialog about the ing to fear. The altruistic motivations European perspective. I was The last, short, chapter is on build - return from effort and dues. future of the technical journal, i.e., that gave birth to the IHPVA and the thrilled to read about the ing your own recumbents and fairings, Competition is a very useful public how it can reach more people who HPVA are still 100% valid. pioneering efforts of Paul and is useful without being encyclope- relations tool in that can bring aware - would like to receive it without being Without visible progress and growth Rinkowski, of whom most of dic. At the end is an appendix of recum - ness of the HPV concept to the general a member of the HPVA, how costs can in any endeavor, enthusiasm wanes. us in North America know too bent resources (e.g., the addresses of public in a dynamic and exciting way. be shared, how and where production, Yet, the invisible foundation that sup- little. He lived in Leipzig, and builders and suppliers, clubs, web sites Competition also can help motivate, via printing, etc., should take place. ports any entity which enjoys healthy built a startling array of dif- etc.) worldwide, which will be appreci- the promise of a tangible reward and At the present time, some 22 techni - sustainable growth may well be deemed ferent recumbents from 1947 ated. emotion, the creation of new innova- cal libraries around the world are sub - its most important. Our rock-solid until he died in 1986. This book should be read by every - tion. However, for this type of explora- scribers, and it would be nice to attract foundation is the acquisition and dis- The second chapter deals one contemplating designing and build- tion to have a meaningful purpose com - more. semination of knowledge about Human with using recumbents for city use ing a new recumbent. It is very good petition must be ultimately applicable —Jean Anderson Powered Vehicles. and on tour. Good advice is freely given value. to pragmatic applications. A clutch — John Snyder for all manner of topics and conditions, of good color photos —Dave Wilson I think that the amount of competi - even some at an extreme at which this appears at the end of this chapter. tion is good as is. However, inclusion
22 Number 53, Spring 2002 Human Power Human Power Number 53, Spring 2002 23 International Human Powered Vehicle Association IHPVA PO Box 1307 San Luis Obispo, CA 93406 USA http://www.ihpva.org