Materials o Mechanics o Physiology o Engineering o 4.rodynamics

Bicycling Magazine's Newsletter for the Technical Enthusiast

Winter 1985 Volume 4, Number 5 $3.00

meant by the phrase, "good brakes can III THE LAB make you go faster." Of course, brakes still IN THIS need to perform their basic function: stop- ping the bike as efficiently as possible. Espe, 'SSUE cially on commuting and touring bikes, IN THE UB Mechanics of brales are needed for panic stops and for Shimano's New Dura-Ace maneuvering through Iraffic. And ATB ridhg brakes are designed on the theory Braking is always more fun if unlimited bmking force Performance is available. that yu can go faster with good brakes. Engineer Shinpei Oka- Part 1: Desigr of tk jima expLains here why low fric- tion means better control. Shimano New Dura-Ace SAFETY Braking System Bike lights today seem lretty crude compared to most other cy- Shinpei0kajma cling components. It's not be- eause the laws of optics and. elec- Auto racing drivers always demand good ticity are a mystery. In this test brakes on their cars, but not because they o/ 29 pofular headlights, the Ro- plan to come to a screeching halt duling the dale Product Test Lab a race. Rather, tley need tle precise zalr?,l- found Lving abilitJ that a fine-tuned braking sys- glaring 300-to-1 diffcrenrc in tem can deliver. For this reason, improve brightness betueen brands. ments in cai brakes have kept pace witl other automotive developmeDts, such as greater engine horsepower and better sus- TDEAS & oPtNtoNS 13 pensions. As a result, the millions of drivers on tJle road today all take lbr granted that tleir brakes will perform flawlessly. DESIGN 14 But in bicycle racirg, the role of brakes The adhesiae-bonding method has been uadervalued fo! a long time. And tle primitive state of many bike brake sys- used to build the VITUS 979 tems today is a reflection of this. alwninum frames was patented The situation is about to change, however last Here is the background Now that mces are becoming faster, and fall. dders of more nearly equal ability are com- of that frocess, told by it's inaen- peting, high-performance bike brakes can be tors. a real competilive advantage. This is what is NEWSLINE 16 Mt Ohajina is Assistant Matøger of the Det;elofment Section in Shimano's Technical Ed Seott's new Superbrake puts Figure 1: The "geomelric" mechanical Dll*ioa in Osake, He has ptaled a toian. advantage a stop to limp brake calipers. najor mle in deoeloping Shimano's "Neø of brak8 lovors and Galiperc is determined let distances DuPont weaues its Dura-,4ce" lifie of conNrone h, ikcluding the by oFarm as Company brabing sJstem descibed in this article, akd lollows: way into the structural com\os- the SIS ixdzxed shiftiag slstern, diseussed ;n M.A. ol lever = L1lL2 ites business. And other deuelof- his anile in APil 1985 Bike'fech. Mr. Oka- M.A. ol caliper = C1/C2 jima ments of interest. ako races as an ameteur ir, the lalanese M.A. ol cables = 1 e4uiLolerrt of Category 2 eoekts. M.A. ol syslem = (tl/12) x (G1/G2) Our brake research project at Shimano rs New Dura-Ace design. In Part II, scheduled aimed, therefore, not or y at increasing the for the next issue, we will report on a thor- braking force delivered by the system, but ough stopping-distance comparison of both also seeks to refine the degree of braking new Shimano systems against Campagnolo. control a\ailable to the ider. How is this achieved? ln four words: "lcss " Mecharucal Advantage friction, less flex." Specifically, our tests "Geometric found that conventional brake designs suffer from large friction losses, a problem we One variable the designer cannot adi)sl ar- found easy to correct, in part by use of bitrarily is the mechanical advantage of the lubricarlt filled nylon inserts. Once this was bmking system. Mechanical advantage is the done, we conce[tnted on increasing the multiplying factor by which the rider's force stiffness of the caliper arms (through on lhe hand-lever is ampLfied al the point computer-aided design) and cable housings where the brake blocks compress the wheel (by using flat-wound steel casings). rim. The two components which generate The end result is the New Dura Ace brake mechanical advantage are the hand-levers set, on the market for nearly a year, and the and the caliper arms. If everl'thing in the new Shimano 600 brake package, scheduled system were PeiectlJ igid ald had zo losses for release in early 1986. By actual on-road due to intemal friction, then mechanical ad- tests, we have demonstnted that these new vantage would be simply a geo%etic factori be ralculated measuring Shimano systems show as much as 14 per- Fiqure 2: Test setup t0 measure elliciency lhat is, it could b, lengths of the mechanical lever arms of cent sroLl stopping distance, compared to and "elastic recovery" of brake levers. The the In the brake handles and calipers (see Figure Campagnolo Super Record components. air cylinder, under control ol an automatic (Part focus 1). This geometric definition of mechanical this Bihe Tech article I), we pr0grammer, applies lincar ramp displace- mainly on the R&D evaluations leading to the advantage is not the whole story, but it is ments allernating directions, correspond- in useful as a starting point for the designer. phases ing t0 lhe "apply" and "release" 0l Ideally, the brake system should provide lull is 10 brake operation. Time lor a cycle as large a mechanical advantage as possible, seconds. Load-cell dala versus time ale so that large braking forces could be pro- recorded digitally: typical data ale shown in duced with minimal hand effort. But in prac- Fioure 3 below. The 15 kg dead weighl tical designs, a mechanical advantage of corresponds t0 a hand-level lorce (load about 5 is the highest that can be achieved. 1) lbs. The same load-cell "law of ExecutiveEditor Chairman Gell 0I about I The major constraint here is the lev- Rabert C. Flotuer Robert Rodak equipmenl is also used l0 measure etficiency eragei" rhjs sals, cssentially, lhal to in- and recovery 0l brake cables and calipers. crease a system's mechanical advantage you TechnicalEditors President Teulet Hat lelrel Dads Robelt Figure 3: Typical t0rce-versus-time data lrom brake lever elliciency tesl. Point A is lhe stalt 0l "pull" slroke, point C is the end ol "release" slroke, and point I is the instant when Managins Ediror Publisher pulling slops and release starts (i.e., when air cylinder reverses direclion approrimalely 4 Ed Paulka James C. Mccullash seconds aller the start ol the cycle). Point D is the relatively constanl output lorce reading on load cell 2. (Note that outpul l0rce becomes somewhat ermlic du ng the r8lease stroke.) ContributirgEditors CopyEditor/Proofreader Fnd Delons ChaD'l E- Ki,nba Load.cell data lrom points A, B, C, and D are used t0 calculate brakeleuel elliciency and Ga/! ltlein recovery as lollows: elliciency = D / (B mechanical advantage) Da'id Ca,dan WiL A15:sra-l Arr Dire.ror recovely =C/A Atdvth A- Cabe Crculåtlon Manaper Pat GÅlrtth

Bihe Tech-Bnlclinæ Magazjne's Newsletter for the Technical Enthusiase GSSN 0?34-5992) is published qtrarterly by Rodale Press, lnc. , 33 E. Minor St. , Em- naus, PA 18M9. Subscription rates: United States, one year $11.97; two years $23.94i Canadian add $5.00 per year, payable in Canadian tunds; other for eign add ff.00 p€r year (inciudes air mail poståge) payable in U.S. tunds. Single copy pricei $3.00. In" quire about bulk rates. Coplaight 1985 by Rodale Press, Irc. A.l rishts resereed. POSTMASTER: Send address chanse to 8r,, Ircr, 33 E. Minor St., Ern- maus, PA 18049. Second-Clåss Postage Paid at Em- ma,rs, PA 78M9. Bike Tech may not be reploduced in any form without the writteo permission of the pub- lisher. Editorial contributions are welcome. Send inquty or write for suidelines. Include a stamped, self- addressed envelope for relurn of unuscd m crial.

This publication is available in micmlorm fmm U versity MicrolilEs Internatiotral. aill lolljree am s21.3044. Ormaiinouirv lo umv€rsrlv l4crolins lhterna tiona l, 3&r No.th zÆb Roaa. Am A.bo., i,fl 43106. '(Nøle: in this gnph, inpul aMl ouloal toftes aæ plolled with dillerc verllcal scele leclots.) Figurc 4: Results 0l brake elliciency tests. Mechanical advantage is Galculated direclly trom Figure 4 shows the results of these lm- provements. efficiency of the Cam- dimensional measulemenls Ll, t2, C1, and C2. Elliciency and ]ecovery ale measured by Overall pagnolo SR system is about 40 percent, l0ad cell selup sh0wn in Figurc 2 above. while for the New Dura-Ace system, it is about 63 percent, an improvement by a fac tor of more than 11/r. Another way to say Shimano Campagnolo this is: with a hand-lever input of 10 kg l,lew SUPeI (about 22 lb), the force pressing the brake Dura-Ace Rccord pads against the rim' in the Campagnolo sys- tem is about 20 kg (10kg X 5.04 M.A. X Lever mechanical advanlage 4.2 4.2 40Va), rcrsus about 32 kg (10kg X Lever elticiency 950/o 900/o 5-04 M.A. x 63%) t,lith Ne$ Dura-Ace. Lever recovery 950/o 850/o

Cable mechanical advantage 1.0 1.0 Instruments 0n-Board Cable €lliciency 700/o 550/0' For a better understanding of the dy- Caliper mcchanical advantage 1.2 '1.2 namics of bike bmking, moment-by-moment Caliper elliciency 950/o 800/o recordings of lhe impor!ant variables, during Overall mechanical advantage 5.04 5.04 reål on-road performance, are needed. Overall syslem elliciency 6ilo/o 40o/t For this purpose, we equipped a standard 'les/hd with unlined cable honsing. road bike with battery-powered 7-channel instrumentation as follows: 6 strain-gauge force transducers on the ftont and rear bmke must either increase the travel distance at either the whole braking system or to any leverc, caliper arches, and brake shoes, plus the input point (hand-lever) or decrease the component part (levers, cables, or calipers). a speedometer on the front wheel. The elec- tmvel distance at the output point (brake A known input force is applied to the system tronics were set up to take 100 data samples shoe). This law is in direct conllict with two (orcomponent) and the actual oulpul for.e is per second on each of the 7 channels. Data operational requirements for the brakes: then measured (see Figure 2); the ratio of from each run was collected on a cassette 1) the size of an avemge rider's hand sets an input to output, after factoring out the tape recorder, and later played back into a upper limit to the maximum possible lever (knownr gpomelric mechanical advanlage. is minicomputer for analysis and graphing. tra\.ei distance, and 2) the need for a wheel' defined as "eficiency" (see Figure 3). Our test riderc were 3 experienced cy- clearance gap sels a lower limil lo lhe mlnt With this definition, efficiency tells you clists with an average weight of 67 kg mum allowable travel distance at the brake what percentage ofthe rider's hand-force (at ll48 lbl. The inslrumented brke ilself. in- shoes. the levers) is actually transmitted into useful cluding the recorder and battery, weighed Other constraints also come into play. As braking action at the blocks, or, conversely, 16.5 kg 136 lbl. Thus, the total weight of mechanical advantage is increased, for ex_ how much force is (onsumed by inlcrnal lric- bike plus rider averaged 83.5 kg [184 lb]. To ample, the caliper arms and cable housings tion in the system. Force measurements minimize the effects of the extra o[-board package must be made stiffer (thus bulkier) to resist taken while the components arc in , otion weighl, we mounted the instrument gravity. lhe larger forces. Aiso, if the mechanical ad- (points B and D in Figure 3) express the dl- low on the bike near the center of Iantage is made too large, the rider loses an araic t'ictio characleristics of the system, The tests were run on a straight tmck of rmportant sense o{ control. .ince the differ_ while the slatic 'breakaway" friction i' flat, dry asphalt at the Shimano factory. ence between "light braking" and "pit shown in the droop that occurs from point A Since the track was indoors. we were work- chover" would be but a fe"v gIams of 6nger to B on the graph. ing at room temperatures with negligible pressure. From tests like that shown in Figure 3, we wind. Two separate test series were run: one with the riders in "upright" position Juggling all of the above tmde-ofJs leads to found that conventional bmke components the conclusion that a mechånical advantage suffer from surprisingly large friction losses. of about 5:1 is optimal. In other words, These losses are a matter of concern fol brakes with a much smaller mechanical ad- three reasons: rantage could be improved b1 a geometrir 1) greater hand-force input causes rider fa- re-design to modily the lever arm distances. tigue, However, we find that most existing topline 2) friction dulls the sense of braking control sidepull brakes, such as Campagnolo Super and precision, and Record, are already close to our "ideal" me- 3) to overcome friction, stronger return chanical advantage of 5:1 (see Figure 4). For springs are needed, which, in turn, have the Shima[o New Dura Ace design, we adverse effecls on faclors #l and ,2. specify a "geometric" mechanical advantage For these reasons. we decided to attack fric- of 5.04:1; this is achieved by a ratio of4.2:1 tion losses as a priority in the new Shimano at the hand-lever and 1.2:1 at the calipers designs. The result is that a lubricant The real world now enters lhe dis.u:sion: impregnated nylon material ("Dura-Con") is brake components are t?ol perfectly rigid, used at all points of moving contact in the and they all do have frictiofl losses. Thus we New Dura-Ace and new Shimano 600 parts. introduce the term "eficiency" to help sep- In parlicular, we found that friction between ante these factors ftom the purely geomet- the caliper arm and return-spring. a chronic ric mechanical advantage discussed above. problem area, benefits Irom this treatment (see Figure 5).

Efficiency Figure 5: ln new Shimano 600 design, a " "Fo, cluitt, tE d;stinsuish betuee 'b,aki g fol lubricant-Iilled plastic sleeve reduces (the the bruhe lads asdinst the in) akd folce Prassi,ts rubbing lricti0n between caliper alms and We define "efficiency" in a way that s '\to?tins lalce" (tha o,erdll rasultant lone that slatus easy to measure and that can be applied to return spring.

BIKE TECH (bral

D1'nanucs

The most valuable use we found Ior the momenr by moment data was for gaining in sight into the d!'namics of the braking pro- cess. For example, the maximum instanta neous deceleration we measured on each run was in the range of 8 to I m/sec'?, and our Figure 6: Typical dala from lnstrumented Brake Tests. Rider making panic stops lrom 25 mi/hr; hands in dr0p position. Nole that rear brakes conhibute very litlle stopping fotce.

Figure 7: lnstrumenled Brake Tesl Resulls. Averages 0l 3lrials by each of 3 riders.

Riding Position UPRIGHT CEOUCHEI) (hands on brake lever bracket) (hands on drops) Shimano Campagnolo Shimaro Shimano Campagnolo Shimano Brakes Under Test New Super as 7o o{ New Super as Vo ot Dura Ace Record Campagnolo Dura Ace Record Campagnolo Stopping Distance [meters] 12-93 15.67 82.5%t t7.57 13.39 86.4To lfeetl 51.41 3?.96 43.93 Stopping Force [kg]' - average u.7 u.2 l43.6Vo 38.3 33.5 114.3Vo - maximum 50.1 32.4 r54.6Vo 54.6 44.3 .lVo b 1 Deceleration [m/s'] - average 4.67 3.70 126.ZVo 4.73 4.t7 1!3.4Vo - maximum 8.00 6.73 118.990 9.37 8.43 111.17o Cable Tension [kg]' at Brake Caliper - average 25.7 t» 115.870 29-07 91.5% - maximum 37.8 32.9 ll4.9Vo 40.6 42.4 95.9% Response Time [sec] 0.112 0.149 75.2V0 0.143 0.162 88.3% (time to reach (time to reach 10kg stopping force) 20kg stopping force) 'conwtsion lacto,s: hs x 9.8067 = Newto s, hs x 2.2046 = lbt. \oaoersion lactor: n/? x 3.2s03 = fike?. SAFETY

Believing is Seeing

Bicvde Headliqhts Test ReporT

Dæid Sellers

It's probably fair to say that lights are one of the most under-deveioped components on the bike. That's exactly the reason we started, two years ago in Rodale Press' Product Test Department, a series of tests on a wide variety of headlights and taillights. We wanted to report on the state-oI-the-art Fiqure E: Results ol "lreadmill" tests. With the bike coasting at 40 kmlhr, a known coflsrarl and see what areas might need improve- hand-leuer force (deadweight) is applied, and the resulling stoppinq force (lrom the ment. The "Night Sight" article iuJuly 1985 caliper.m0unted strain gauges) is recorded. Data points plolted here are avelages ol three Bicycling snmmarizes of this work for the t als at each level ol input.d general reader. In this Bikr Tech repott, we explain in de- tail how the headlight tests were done, and highest individual reading was 9.37 mlsec'z. present a large amount of the background According Lo convenlional theoryb. the maxi- Stopping Force data. (See June 1985 Bihe Tech lor a rcr/rtrt mum possible deceleration (whhout fort!ård on the reflector tests,) In particular, you'll pitchover) is aboul 5.45 m/sec' (i.e., 0.56 We also ran the instrumented bike through find here a complete listing of the headlight G). We explain this apparant discrepancy by a series of tests on an indoor "treadmill" beam intensity data, actual night photos of noting that lhe Whirt and Wilson ånalysis is (i.e., a large wheel whose rotary inertia was the Iights "in action," and time-versus- essentially "static," i.e., it calculates or y similar to that of a rider in linear motion). voltage discharge cuffes for battery lights. the deceleration needed to initiate the pit- These tests were similar to tlose reported Such data will be valuable in developing new chover motion. and does not consider the by Rob van der Plas at the German TlrV and improved bike light systems- But you'll dynamics of what actually happens when a Laboratory in Essen'. also find it useful e\en if you are just looking greater deceleration is momentarily applied. The main purpose of our tests was to ap- for further insight into buying new liShts, or Such a dynamic calculation requires knowl- oly a know\ corlstant hand-lever force (dead' gerting the most out of your exislng equip- edge ofthe polar inertialmoment ofthe bike/ weight) and then measure the resulting aver- ment. rider system about the ftont-tire contact age stopping force' via the caliper-mounted In Table 1, you'll find a list o{ the head- patch, and is a subject for our further study. strain gauges. The results (see Figure 8) lights we tested, along with their electrical ln any case, the pmctical implication of this basically conirm the "eficiency" data re- ratiags, bulb data, and measured light out obseruation is this: braking decelemtiorc o{ ported above. That is, for a given hand-lever put. These lights were selected to be fairly more than 0.56 G (the Whitt/Wilson "theo- input force, the New Dura-Ace produces a representative of products lhat were avail- retical maximum") can in fact be achieved stopping force about 50 percent larger than able at the time of the tests, and cover ali for very short instants. Of course, skjlled that produced by the SR system. The good three types of systems that are in use riders have known this for years: they agreement between these two independent (battery-powered, genentor-powered, and "pump" the brakes and, when pitchoverjust tests is encouaging; it suggests that either hybrid systems incorporating both battery begins, they release bmking pressure just method could be used as a realistic brake and generator). enough to return to 2-wheel contact. Most performance test. ofthe time, these fluctuations happen so fast Part II of this report, scheduled for the that they are probably instinctive on the next issue, will report the results of Conspicuity rider's part, rather than conscious. Never- stopping-distance tests on the new Shimaro theless, we now have reason to say that a systems. What do we really want from a bike head- high-per{ormance (quick-response. low fric- light? In a word or to se? and be seen. 'Rab Vafi der Plas, "Stobping Pober - Blak t{o, tion) brake system can help the fasr-brakiag Ideally the light should illuminate a large Blocks on Test," Bicycle Magazike (London, rider in making these ultra-rapid high-G ma patch of road as far ahead of the bike as pos- England), February 1985, ,ages 34 39; and neuve6. Indeed, the Figlre 7 data show sible. Obstacles like potholes, sewer gmtes, "Stotlins Power II," /Bicycle, Seqtember 1985, that New Dura Ace brakes averaged consis and dead animals &m come up quickly, so ,ages 38-39- tently higher peal decelerations than the you want to have time to recognize them and tAl1 Campagnolo SR system. boel gtuufid, auelage skltit g forte F is react by braking or swerving. If your total piuen br the fofinula: time for recognition plus reaction is about F=MxIP/exD,bhele two seconds (a conservative value), then, bF.R. Whitt and D.C. wilson, Bicycli,s M = total oehirle ass, Science, 2r1d. Edition, The MIT Press, V : initint stecd uhen blakes are abll;ed, and D d S.lLe^ is Protect M,1nøge,ih tht Rodala Press Cambridge, MA, lages 197-198. D = totdl sklli e dislanæ P /ad,Æt Testing Deiartnent. Table 1: Electrical ratings, measured light intensity and other dala 0n headlights in the test.

Photo ehic Dåts Electrical Retings Measuled Lig[t Inten6ity (cendela] A,g. MrDufact0Ier. B€tåil Weight Power Bulb Data Zone Zoæ znrc Tare Zones Model Number Price (oz) Sourcet model *, waits volt6, amps.6 t23{ 14 Commenis

Cycle Pro l?710-000 $7.95 11.3 GEN: 3$, 6v at 8.3mph #1482, 2.4\|.6.0v. 0.4a 80.0 18.0 4.6 1,0 '25.9 t2

Panasonic #MD-88( $13.95' ll.5 GIN: 3\r. 6r at 8.3mphi 11482 or /605, 3.0\r, 6.0v, 0.5a 258.0 æ.0 10.5 r.96 i4.8 12

Rinder rl0T $9.50 8.2 GIN:3\r,6! at 11.3mphr #1482, 3.0w. 6.0v, 0.35a1' 38.0 18.0 5.3 1.64 æ.7 12

Schwinn #M265 $12.95 12.1 6[N:3w,6v al 25mpht #1482 or /605, 3.0\r, 6.0v. 0.5a" 1i6.0 40.0 I1.0 0.4,1 51.0

Cyde Pro 1177-10'060 s11.m'z 3.0{ GEN: 6$, 12v at 9.33mphr 189K.6.0$, 12.0r, 0.5a 1t2.0 46.0 12.8 2.8 42.0 rJ. ts

Cyde Produch #333 $8.99'? 3.04 GEN: 3r. 6,r at 15mph' 11482, 2.7§, 6.0!, 0.45a 17.0 19.5 16.0 t.6 13.5 B, ts

Cycle Products 1338 $9.99'2 4.84 GEN| 6w. lzv at l2nphr ,89.6.0{, 12.0v, 0.5a N7.0 84.0 31.0 2.9 103.0 rr. ,.,

II{v t0153m 2.?{ GEN: 3w, 6r at l2mph'- Special Halogen 2.4w, 6.0r,0.5a 600.0 13.0 5.6 1.2 154.0 rr. 15

Panåsonic IMD-8sC sl5.92'? 3.41 GEN: 3w, 6Y at 21.7mph7 ,1482 or #605,3.0$. 6.0r,0.5a" r58.0 u.0 8.3 0.4 4?.4 u. §

PaMsonic #MD.85tB $18.95'': 5./ GEN: 3w, 6v at 21mph7 #1482or #605, 3.0w, 6.0r, 0.5a'r 82.0 43.0 0.2 U.6 u. ts

Rinder #130 ,{.6{ GEN: 3w, 6v at 25mphr r11482, 2.1N. 6.0!, 0.35a 190.0 40.0 8.5 0.21 59.0 13. lj

Sanyo #NH-050-SBE $15.92r 2.8{ CEN| 3w, 6v at 13.3mph *1482 or #605, 3.0N.6.0\', 0.4a 262.0 ,18.0 9.3 0.16 79.8 t2

Sch{inn Le Tour #04190 $18.95'z 4./ GEN| 3w, 6Y at llmph7 i1482, 2.4\r,6.N, 0.4a 692.0 6.1 2.6 0.16 177.0 13, ls

Schwinn Traveler #04280 $1r.95'z 5.6{ cENr 3N, 6r a! gmph #1482, 2.4$,6.0r, 2.4w 112.0 25.0 5.6 0.16 35.0 13, t5 gmph Searc #48103 $9.99'z 4.81 GEN| 3w, ft at #1482, 2.iN, 6.0r, 0.45a 175.0 54.0 7.8 0.48 59.0 /i, lj

Sears #48112 $12.95'? 7.5{ GEN:6N, l2v al14mph' #89 or rlI155, 6.0w 12r,0.5a 86.0 r32.0 68.0 1.44 71.0 ,3, lJ

Soubitez #305-L $4.e# 3.0{ GEN: 3N, 6v a! 12.3mph7 Special Halogen, 2.4w, 6.0!, 0.1a ?43.0 13.3 3.8 0.28 190.0 7i. lj

Soubitez 1305-809101 $19.95: 2.8i Gf,N: 3w. 6v ar 10mph 11482. 2.4w.6.h, 0.4a 345.0 12.6 3.6 0.16 90.3 13

Union 198.39 $19.20'? 4./ GEN: 3§,, 6v ar lornphi #1482, 3.0u, 6.0\,, 0.5a 378.0 å.0 6.0 0.16 101.0 r3, rj

Union #98.14 $10.45' 4.d GEN: 31l, 6v ar l3mph? 11482, 2.4n, 6.0r', 0.4a 444.0 11.4 2.8 0.16 114.6 i3, 15

Berec #305 $9.99 g.3a 2 D cellsl IPR-6, 0.75w, 2.5r', 0.3a 178.0 8.5 2.8 0.16 47.0

Cat Eye ,HL-æ0 $5.90 6.14 2 D cells3 #14, 0.75u, 2.5r,0.3a 102.71 3.68 0.65 0.05 m.8 cEv #5619 $6.r5 4./ 2 C Ce[s' #14, 0.75r, 2.5v.0.3a 71.0 3.37 1.04 0.32 18.9

Cyde Producis /302 $s.99 4.81 2 C Ce[s'g #14, 0.75{. 2.5r,0.3a 40.0 4.9 2.?? 0.26 12.0 13

REG /698 $7.95 1.81 2 A.A ceus'o ,233, 0.5\-. 2.5!,0.2a 6.85 2.89 0.98 0.9 2.7

Roadlight s48.953 4.31 Hitachi lead-acid Special Halogen, 4.95u, 1.5v, l.1a 706.8 76.0 20.0 4.25 n1 12 gel-cell, rechgable 6r, 4amp'k., mounls on seat tube, æ,2 oz. $ith mount.

Spartan §41.003 17.64 Gould lead-acid gel-cell, G.E. H7551 Halosen Hala.Beam rechgable., 6r, 4.samp'fu, mounts sealed beant 8.0w. 157.5 lt on seat lube, 3902. vith mounl. 6.0\', 1.:,3a

$7.95 5.d Special4.5v, flat. #13, 0.7$, 3.5v, 0.2å 69.0 0.86 0.09 18.3 ,,r European type batlerv, avail. in bike shops,4.2 oz.

$69.95" 6r Ni-Cad batterl pack, L2 SpecialHalogen. amp-hr, Sanyo dFapower type 4.0rv, 6.0\'. 0.€6a 531.0 179.0 ?3 genemtor, modified lor higher output,I oz.

Bicycle Lighting Systems $33.00 31.5 tz G.E. 4512, 2.5$ 4.7I,0.5a 17.5 40.1 /r

AlternaE Bulbs $12.00 G.[. H7551,8.0w, each 6.0v,1.33a 3r4.7 199,5 90.0 t.8 15:17 lr

Alternate Bulbs r)12.00 c.E. H7553, 12.0w, each 6.0r, 2.0a 456.0 433.0 63.0 3.8 238.0 /J

Alternate Bulbs sl2.00 c.E. H7s54,20.0w, each 6.0!, 3.3a 582.0 485.0 99.0 1.0 291.0 r/ Alternale Bdbs sr2.00 G.E.4411,35.0§, each 12.8\,2.75a I206.0 195.0 I97.0 6.5 399.0 iz Alternate Bulbs $12.00 6.8. H7610, 50.0w, each 12.8!,4.0a 2757.0 691.0 103.0 12.8 891.0 ,7 when you're traveling 15 miles per hour (22 in less than ideal conditions rain, fog, poor cause repeated bulb failures, and conve6ely, feet per second) vour lighL should shine driver vision, drunkenness, etc.-and you that a slightly discharged battery will pro- about 44 feet ahead. It's also good to have see the overiding importance of conspicu- duce a noticeably dim light. Unfortunately, sone lighi on lhe road in the immediate vi- itv. leu of today s bicycle lighting syslems in cinity o, the front wheel. This will keep ob- clude a voitage regulation circuit to compen- stacles that you spotted from further away sate for vafiations in generator or battery Light Bulb Physics Irom getting lost in shadow as you get closer voltage. to them and prepare to swerve. Halogefi bulbs produce roughly twice as job Another of a bicycle lights is to alert The single most important factor which much light, compared to conventional bulbs other motodsts to your presence. Since determines the brightness of a headlight is of the same physical size and electrica.l watt- nighttime collisions wilh cars are a major the choice ofbulb. In Table 1, we list the bulb age rating. Halogen bulbs are still "incandes cause of injury to cyclists, this aspect of light ID numbei, along with it's rated wattage, cents" (they have a glowing filament), but performance is most important of all. Con- voltage, and current draw, for the bulbs that the halogen gas (usually iodine or argon) that spr'altir, is the term that refers to an object's were factory-supplied in each light. (We fills the glass envelope allows the filament to abiliry to visually.all arenlion ro itself. For don'l know whether manufacturers consis operate at a higher temperature since it su, bike headlights, consplctity from the side, as tently use the same bulb type in their head- plesses evaporation of metal ions from tle well as from straight ahead, is a factor. Many lights, or iandomly switch bulbs according to filament. Unfortunately, halogen bulbs are lights, tkough random scattet emit at least what is "available.") IrI any case, the bulb's even more sen§itive to voltage fluctuations some recognizable light to the side, but electrical wattage mting is a good clue to it's than conventional bulbs. some lights are much better at this than oth- light output. Among the lights we tested, Another point to remember is that hdivid- ers, as we found in photometdc tests. electrical wattage covered an incredible 100- ual light bulbs of the nominally "same" type There's an ongoing debate in some quar- to-1 range; ftom a maximum of 50 watts (in can vary quite a lot from each other. This terc as to exactly how bike lights "should" the Kesrney system with GE #7610 bulb), means that you might dmstically change your (see perform February l9M Bihe Tech, page which equals a small car headlight, down to a light's output.iust by switching to a dillerent 16, and "Ideas & Opinions," in thjs issue, mimimum of ll2 watt (in the REG #698), bulb of the same part number. For our pho- for example. r One reason for thjs debate is about the size of a penlight bulb. Most of tle tometric tests, \re used the bulbs as supplied that there is no definition (yet) of a "stan- other lights fell in the 2 to 3 watt range. wilh lhe tesr lights. But in a .eparate experi- dard" measure of conspicuity that could ap- Thus, iI you're looking for a real$ bright ment, we tested several bulbs of the same plv lo allcases. The surrounding visualenvr- headlight, you should first ask about the type from the same manufacturer, in one ronment plays a major, hard-to-control role. wattage of the bulb. light. We found that the range of light output And recognition is a psychological as well as The bulbs'mted "nominål voltage" is also varied by roughly +/- 15 percent about the optical process. important. In fact, the light output of incan- average of the group. We were told by bulb In any case, a point of geneEl agreement descent bulbs is ,rtlerrel! sensitite to the ap- manufacturers that halogen bulbs and the is that a light must be r/rrc, bighter than its plied voltage. According to manufacturers' larger sealed beam incandescents show surroundings to be recognized on the road. empiricaldata, the bulb's light output is pro- much better uniformity than the small In particular, perceptual tests show that a portional to the applied voltage raised to the "flash]ight" type bulbs. driver who is not anticipating the presence of 3.5 power. and the bulb s lifetime Oefore The posirion of rhe filamenL in (he bulb has an object will generally fail to see the object burnout) is inversely pioportionalto the 12th an large effect on the resulting beam pat- unless it is more than about 1000 times power of the applied voltage. tern. This is because the pattern ofillumina- brighter than the dimmest object than the This means that a slrgrt increase in \oltage tion is actually an image, somewhat dis driver could detect if his eyes were fully wil catse a significant inc/ease in light oijl- torted, of the filament projected onto the adapted to total darkness. In short, this p]ut, and a lalge decrease in bulb life. Exam road. We found that, with some lights, the means that a light which looks bright to you, ple: a mete 5 percent increase in voltage beam pattern could be improved simply by the rider, with partially dark-adapted eyes, (0.3 volts in a 6 volt system) willincrease the rotating the bulb a fraction of a turn so the will seem mu.h dimmer to motorists gazing light output by about l8 percent, and will cut filament was exactly horizontal or vertical. into their car lights. Add to this the fact that lhe lifelime in half. Thus. ir's no surprise For these lights, we positioned the bulb to bike lights are often competrng ior attention that nrnning a generator at high Speeds will produce the brightest central spot.

l-Pice i cludes taillighk. 2-Pice includ.es genelator and taillight 3-Price includes entile slstem: head.lights, battery, tailtight, charger, wiing, and molttltilrg hardu)ale. 4-lUeight of head.light onl! uithout ba.ttery or geflelatol. s-Fol generato6, mah fact ./er's ,rornihal oltdge dnd uattage out\ut ralings ale giuek. MPH ifidicates the /oad sPeed, accord;ng to oul tests, at u)hich the generator Produces its norn;nal lated uoltage- 6-Closest eq .iaalent bulb desigflatio fron Genenl Electic Mini.at re Ldrnl Catalog. Nominal bulb wottoge, aoltage, and anrelage giaen. 7-Conoektiofial desigra gefieratol diaes b! contact w;th tire sideuøll. 8-lVeight of tøo "D" cells: 5.8 oz. carbon zinc, 9.4 oz. alkaline. g-We;ght of ttuo "C" cells: 2.8 oz. calbon zinc, 4.7 02. alhalike. Lo-\Ueight o/ two "AA" eells: 1.1 oz. calbon zinc, 1.6 oz. dlhaLihe. 1l-lfid.icates eq ioaleit bulb desigrratioh. listed is not necessdilJ a close match. 12- H?adli4hl mounls on lronl lorh blade. l3-Heqdlight nounls on handlebor slem. 14-Hea.d.light t ounts on hokdlebar. L,-Generator flouflts on rear sØt sta!. l6-Comqlete ststem irlclud;ng headlight assertbL! u;th H7553 latu], 7' taillbht, leød acid rechargeable batteft, chorgel, siace lørrø, bulb and flugs: $150.00. l7*Alteltøtire batteries aoailable hom Biqcliltg Lightirlg Ststems: Lead.-Acid. rechargeable battery: horninal 6-oolt,4.5 amp-houf, ueight: -Gates 42 oz., 950.00 -Gould. Gelyte rechargeable battery: korfrihal 6-0olt, 6 ahb-hour, ueight: 40 oz-, $50.00 BEREC w/ C-Z cells BEREC w,/ Alko lin e

3 zz 9 z.o

3 2.+ E J

tifr. (hinuLs)

Figure 1: Typical graphs 0l hattely voltage vs. time. GT Rood Liqht SPARTAN

c 6.5 3, 6.3 P e.2 2 62 9 5.r 9 6.1 E 60 ; 5.9 : 5.e 3 s.a 3 s.a E 57

choice was that the voltage decrease was are not being used- They are not unduly af- much less drastic here than in the fust few fected by tempemture variations, and they Batteries minutes of operatio[. So, for each battery supply a rather constant voltage during the light, we noted it's voltage at the one-half discharge cycle, providing reiatively con- Batteries are assigned a "nominal" volt hour point, and applied that voltage to the stant illumination. (Non-lechargeable batter- age rating, but the drfral operating voltage bulb for the photometric tests. ies show a more drastic drop in voltage as is usually less than this rating and diminishes Which type of battery is best? The stan they discharge.) However, ni cads grow dim with time as the cell discharges. And as the dard carbon-zinc cells are the cheapest, but very quickly when their charge finally is de- voltage drops, the light becomes dimmer their capacity is substantially reduced at the pleled: see. for example. the sharp drop in (according to the 3.5 power law mentioned currenr drains rapproximately 0.3 amp) im- voltage in the Kearney light with GE #7610 above). In planning our light intensity tests, posed by small bike lights- Our voltage-vs- bulb after one hour of continuous use, we at 6rst intended to use liesh or fully time tests in Figure 1 jllustrate this for the Lead-acid battedes, also called gel-cells, recharged batteries in each light. But we felt Berec 305 lighl. Nole lhar. \ ith carbon-zinc are the alternate choice for high capacity that this would not be realistic. since most cells, the battery voltage drop after 2 hours' powe' sources. They are chpaper than ru riders do not install fresh batteries for each usage is much greater than with alkaline cads, but they can be damaged by deep dis- dght ride. So we decided to measure how cells. Another disadvantage is that C-Zn cells charge. In any case, ai1 rechargeable batter- battery voltage changes with time, in each don't store well in hot environments and ies are ieary and must be taken off the bike battery powered headlight, by operating the perform poorly in the cold. Thus, if you want for recharging (ur ess you have the Velo' unit with fresh ror fre'hly charged) balleie. non-recharge batteries for regular night- Lux combination system). and measuring the voltage across the bulb dding, you'llprobably find alkaline cells to be every few minutes for pedods up to 2 hours. more reliable and economical, despite their Generators The resulting voltage-ra,"srrs-time gmphs higher cost. (Figure 1) are quite revealing. In all cases, For higher power outputs, you'll probably In designing our test for genemtor sys- the voltage diminishes rapidly in the first few need roch.rrgeable cells. Ni.kel-.admrum tems, we had to deal with thc fact that a gen minutes of operation, and then continues cells are an order o[ magnitude more expen- erator's output depends on the speed of the dropping ar a :lo\ cr rate. Aier examining sive than throw-avrays, but they can be rc- bike. I]sing a set of training rollen powered thcse curves, we decided that the voltage af- charged hundreds of times, and can tolerate by an clcctdc motor, we determined the bike ter one-half hour of oleration of the light deep discharge without damage. However, speed necessary to achieve the system's would be a realistic "standard" value to use ni-cads require regular (every couple of rated voltage with the headlight on. These in the photometic tests. One reason for this months) maintenance charges even if they results are listed in Table 1 in the "Power WONDER KEARNEY w/ #7610 bulb

12.6

12,?

! r 1.6 9 ,,.u e r r.a 3 , r.z E 1i.o

KEARNEY w/ $7553 l>vl6 VELOLUX

g 6.5 3 5.3 t 6.2 3 6.2 9 6.1 9 6.r r 50 5 5.e 3 s.a E 57 E s.'

positions to the left or right of Source" column, and the variety is surpns Photometry Grids viewing /a/ ing. Most systems reach their rated voltage the beam center, extra gid data points are at reasonable speeds, between 10 and 13 Our main purpose was to measure the included in the four extteme corners of the mph, but the Schwinn and Rinder systems headlights' light output via photometry test grid layout. lwo verli- make vou pedal al 25 mph for full oulotrl ing. The two industry standards for such Our gnd is labeled wil h difterent We also discovered, in pilot tests, that the tests are: British Standard AU-155. intro cal axes because the two standards specify generators ch.rnge lheir oulpul characleris_ duced in 1973, and ISO Draft Proposal6742/ different ways for aiming the headlight and tics as they warm up. (The data mentioned 1, which is currently under review in more for establishing the origin of the coordinates. in the previous papgraph was taken with the than a dozen countries through the Interna- BSA defines the origin of coordinates as the units cold.) Thus. for purposes of the light tionål Slandards Organization in antictpalion bightest spot in the beam. ISO say§ that the intensity tests, we declded to disco fiect the of final acceptance. body of the light must be ali$ed straight (which generalors entirel). and applv lhe m"nufac_ Both standards specify measurement pro- rhead and horizontal is defined as the turer's rated voltage to the bulb directly cedures and set forth accebtance ualues (the 0-degree point). and then requires that the 1/2 degrees tom an independent power source. It's trle minimum light intensity needed to "pass"). brightest spot must fall 3 verti- that this procedure rgnorcs the different Since it takes countless hundreds of data cally down ftom ihis position, and 0 degrees speed-r2,"srs-voltage curves of the different points to describe a beam pattern com_ to the left or right. Moreover, ISO requires generators, but it seemed to be the only way pletely, measurements are called for at only that light intensity must not exceed 120 can- to produce consistent results. a limited number of points. Unfortunately, dela anywhere above the 0 degree verlical The Velo-Lux unit is a clever hybrid; it the two standards cail ior dilferefit meas'Jre line, presumabLy to avoid the headlight beam I uses a ni cad battery built into the lamp ment points (though there is some overlap) shining in the eyes of an oncoming motonst. housing, and includes an optional generator and also hdve difIerent acceplan.e !alues. Note also that ISO requires a much brighter which can power the light, or charge the bat- We have combined the gdds from both spot in the center of the beam: 400 candela rery rwilh lighr offl. or both. wl'rle riding. BSA and ISO to produce the measurement minimum versus BSA's 100 cd minimum. This system could be doubly cumbersome or layout shown here in Figure 2. This resul doubly convenienl, depending on your pref- tant grid specifies light intensity measure- Te$ Set Up erences. We decided to test this system ex- ments at 28 points. Most ofthese data points clusively as a ådlLr:y-type system, since the are located near the center of the beam pat In the test set-up, a light-tight partihon interactions between generator and battery tern (within 10 degrees up or down, and 20 with a small hole near its center was con- would be difficult to quantify without exten- degrees left or right of the beam's center). structed near the center of a light-tight test- (see sive further tests. To measure the headlight's conspicuity lrom ing room Figure 3 ). The basic idea i' horizontal axis 200 10"

o

@

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Figure 2: Headlighl beam intensity was measured al poinls with double 0utlines. Numbers are the minimum values (in candela) parenlheses) specitied by lsO (in and by BsA. shading indicales zones l through 4 tor averaoinq resrrrs ieportJa in'flor" r. to allorv onl! a narrow bcam of light, corre ter) §hich expresses lhe amount of light åt a each zonc. $e averaged the li,llrt inle sit_v sponding to position an exact in the beam point in space being illuminated b)' a distant mcasurenlents iionl all the poinls in the pattern, to reach the photomeler. .ltercdlh. light source, and, r : distance lront source ., 1.. and, re.rrl' rr rlreaoprnpl To be åble to scan all parts pat, ol beam to photometer (10 nleters). atc columns in 'hble 1. !\Ie also report the tern, ive mounted each bike light go 1n a Al :l \\.. -l:,rledb) m,.ur.r rCabike isl-r ovetall averagr: of all four zones grouped to niomeler F)

', 3112" dia. I I +--f illuminance meter on tripod

--Jaiming board/

alternate lripod location zl_ lerurishl anole settins Figure 3: Text Room Layoul.

be an effective feature. with Kodak ASA 1000 speed black-and-white For really brilliant lighting performance, film). one must consider the larger rechargeable For distance markers, we placed white battery-powered lights. Ed Nearney's prod- wood blocks on the roadway at 10 foot inter- ucts dominate this group in terms of sheer vals(see Figure 5 ),and also placed street power, with his s0-watt ,f7610 sealed beam sigrc and a car in the scene. The photos unit putting a dazzling amount of light on the were taken on an overcast, moonless night road. The cost in money and weight (batter- with no sources of slray light (e.9., street- ies) to support these powerful lights may lights) that could obscure the results. make them impractical for some riders. Note that these pholos do flot show ?røctl, Kearney does offer cheaper light/battery what the night dder would see. The human combinations that also perform nicely. visual system can adapt itself to a much Finally, the Velol-ux deseraes a good rat- greater mnge of conditions than any black- ing for its flexibility (battery, generator, or and white camera. For example, rrith a dim both), compact design, and respectable illu- headlight, the rider's eyes become more minåtion- "dark-adapted," (i.e., the pupils open wider and the visual pigmenl Iightens), thus making Night Photos: the scene appear almost as bright as if a stronger headlight were in use. The night Figure 4: Goniometer mounting lo] What You See Is What You Get photos take no account of this physiological headlight with Galibrated angle settings. adaptation of the visual system. But how does the illuminated road "re- Still, the night photos can be useful be- We fouod that tåe beam patterns in the ally" look to the rider? To answer this, we cause, in a purely orrød, sense, they offer an night photos seemed to lallinto serefr distinct took nighttime photographs of the beam pat- exact measure of the amount of light reach- gzorrs, as listed here and shown in the ac terns in a realistic settilg. Each headlight ing the rider's eye. Moreover, they go a step companying photos: was set up on a stationary stand (camera tri beyo[d the lab photometry measurements A. aetl bright; B. bight diff*se slot; C. pod) at handlebar height and supplied with a (where the lights were aimed directly at a bright slot; D. ol)a.l slot; E. diffuse sqot; E constant, regulated voltage (the same volt- vertical wall) by projecting the light's beåm d.im and diffuse; G. d.i.rn sfot. age used in the photometry tests). A Nikon out,vard toward a realistic scene. Simple ge- There seems to be no overall consensus 35 mm camera with 50 mm focal length lens ometry says that the beam pattem on a ver- among riders as to which beam pattern is (roughly the same as the eye's 53 mm focal tical wall will be differelt than that obtained best. Perhaps the ideal would be to have an length) was set on a tripod at simulated when the light shines onto the open road. In adjustablebeampattet[, so that either wide- rider's eye-heiSht (slightly above and behind short, the beam pattern you will see on the angle or bdght-spot illumination could be se- the bike lighO. We used idrrlr'røl exposure road is more like what is shown in the night lected. The moveable reflector system found settings for all of the photos (shutter aper- photos than is measured in the ISO or BSA on quality flashlights could probably be ture of f2, and shutter speed of 1 second, photometry tests. adapted for this.

11 blocks at 10' inleruals A. Kearney U Halogen #7610 bulb

10' to bile liqht and camera F--)

Fiqure 5: on{he-r0ad beam patterns 0l seuen lights, spanning the range lrom brightesl lo dimmest; all photos taken with same exposure setlings and camera locali0n. Drawinq shows photo setup.

change batteies anderwater with no ill ef- fects (all References 0verkill electronics are sealed). You can drop it off the bike in motion, and it keeps 1. "ISO P/ofoses Neø Intenalinnal Bicl- flashing. The bulb never burns out, The cle Lightihg and Reflectoization Standards' '; Why have biycle lighting systems re- whole unit is about the size of a cigarette Fred Delong and lohn Atler.; Bike Tech Vol- mained in such a primitive state for so long, pack. How does it wo* as a taillight? We've rme 2, No. 3, J ke 1983. compared to the developments in most of found that every passiflg car hesitates about 2. "Deaeloping Lighlitg and Reflectoiza- the other components on the bike? It's cer- a half block away while the driver tries to fig- tion Standards" Fred Delong atxd lohn Al- tainJy not for lack of technology in electronics ure out what it is. It doesn't even have a len; Bike Tech, Volume 2, No, 4, August and optics. Fresnel lens to produce the "ideal" taillight 1983. For example, we know of riders who, for beam pattern, but no matter: it's real con- 3. Lightike Eq itrnekt akd Photometic their own night travels, refuse to use spicuous. Gou can buy one for about $60. Tests (SAE Handbook Sulllerhent HS 34); commercially made bike taillights. Instead, through boating suppliers or military surpius Societt of Autornothe Engineers, 400 Com- they ride with a Coast Guard approved ma- channels; ask for NaW Stock No. 6230-00- monwealth Diae, llørrendale, PA 15096: rine distress flasher stmpped to ther under- 067-5209. Some areas may have legal re- lages 23.æ - 23. . seat tool bag. This little unit was designed strictions against using such a strobe on the 4. ISO Slandald 6742/2: Ctd?s - Lighting for use on life rafts and disabled watercraft, highway.) and. Reflectiae Deoices - Photometic ønd so they could be spotted from the air. It's Maybe this is overkill. The point, how Phjsical Requilukents - Palt 2; Intetua- guaranteed to be visible from nine miles ever, is that compact, high-performance tional Standards Organization, 1984. Cofies away at a 1200 ft altitude. With a Xenon-gas lighting systems have already been de- ale aoailable l/on Ameican National Stan- strobe (the type used in photographic flash signed. Where are the manufacturerc who dalds Insrihie, 1130 Brcadway, New Yorh, unils) and a merrury ballery. il runs for nine will turn this technology into affordable bike NY 10018 fot $16 lllts $3 lostage. hours on one charge. Is it reliable? You can lights?

12 normal roadway circumstances.) Then, in- ter an accident (i.e., \\,ith a wheel still intaci). IDEAS & OPINIONS stead of testing the good reflectors thal are The ralialloads of up to 600 pounds are also available. the author tested the reflective fab- far in excess of what is applied, and the test rics and tapes (which are not very bright), and block through which they were applied is not a compared these to the CPSC bicycle reflec- good model of the action of the tire. The tire Superstitions tors that we kno'r have been designed to be applies the load forces to lhe rim largely by dim for their size and weight. changing the forces on the bead wires, and As always, cycling is fuIl of superstition, as Likewise the papers on the stiffness of bicy- only in accordance rir'ith the footprint oI the tire shown by material in Bihe Tech lor lune 85. cle wheels have little pmctical relevance. Take against the road. High radialforces can only be The paper on rellective materials is quite ab- torsional stiffness. The difference between 4X applied for extremely short periods of time, as surd. First, it repeats the two silly supersti and 2X wheels is about 0.001 inch at the pedal when going over a bump. Radial stiffness un- tions that motorists at night don't look along for a 200-pound rider with fulI weight on the der high load has no practical effect on the effi- the road ahead, and that motorists deliberately pedal in 40" gear, and of course only a portion cieney of cycling ,because o[ t']e shorl lime! smash into anything that they see that is not a of that is Iost (hysteresis loss). The lateral de involved) and practically none on success (be cyclist. Surprising as'these seem rrhen so flection is listed in millimeters per pound oflat- cause failure is typically caused by point con stated, they are the literal meanings of the eral force for force values up to 120 pounds or tact between the rim and the rock, at a much statements that detection must be by periph- so (when the rinls start lo fail). In very exag- lower radial load than the tested range). eral råther than foveal vision and that motor- gerated pedaling the cyclist might get the bicy An o1d adage in science says that it is far ists must recognize cyclists in order to avoid cle to 10 degrees to the apparent vertical, more important to ask the right question than them. (Yes, Zwahlen tested detection by pe- which implies a side load of only about 20 to gel an accurate answer to the wrong ques ripheral vision, but only becatrse that suited pounds. In most cycling there is practically no tion. the legal controversy that paid him, and no- side load. and lateral stiffness or strength is where in his paper is there a demonstration importani only whcn spoke. are broken or in John l'orester that this would be the method oI detection in improving the probability of a quick restart af- Sunnyvalc, CA

13 The ed.itots rurl! that will encourage the growth of the sport, The test fittures used b! Akers and Pice for and leave the Stmmicks to rich toudsts and DESIGN the uheel stilfness tests are øaailable for use bi the like. oth?r ?xb?imuters uho u)ish lo l?sl uonous A final point: In extremely demanding, wheel configurøtions arNd leqort on the results. hilly cdteriums where a missed shift is a di- Access to an "a tofiatic" testing mdthine saster, I offer a simple and cheap solution. Historv of the Glued (such as an MTS or Instrorl) is not n?.cessary, Use a freewheel lhal allors )ou to stay in btat it r.,ould be heltfitl. The measurernents the large chainring all the time. A Super Rec- could just as well be taken b1 hanging d.ead ord rear derailleur will hardle 26T, and any- Aluminum Bike Neighh onthe )heel, and measuing deflections one that can't take a hilltn12X or 52X uith d d.ial indicator- So, let s hedr lrom those isn't going to solve his problems with the SIS Frame uho uish to lu/sue s ch tests. or Browning systems. The question af dt'namic-t)ersus-stdtic lodd To bzlance this letter a bit. I would like to bJ Forester, is imfortant. It's extend my appreciation ol Bike Tech for its ing, laised Joh Note: The "glued" aluminun bike frame was certd.inli a tougher job to measure uheel informative and relevant articles. ferfor' recentl! batefited here, at least lartiallJ, last manrr undcr rcal liue idtng ronditio s since. fall (U.5. Pat.nt #4,479,662 issued October ds out, the largest (id)ng Jef{aey Mennies, Folestel loints forces 1984 to Ateliers de lø Riw of Saint-Chømond , Free Wheeling Bicycle Shop oter a bump) last for on\ fractions of a second. France). The late t holder is hnonn in the O e redson for relorti g the PurelJ static tuea- Margate, FL U.5., thlough association with Bador S.A. of suretue ts of Ahers aruJ Pice is that, if and St. Etienne, F/ance, as the b ildel of VITUS uhen illnanic redl time data is colLected, the 979 ("Durulinox") aluminum frames ant) dLtta be it to see the Brandt on Wheels static cdn co?n,ared a.gainst folhs. The latent mahes sbecif.c claims coL dit'ference. Ma1be, u)ith luch, such a corkPaÅ ee/ning dd.hesiae-botxding method,s using cast that stdtic ,neasurements rea.ll' son ttill show I was pleased to see some measurements lugs )ith a "conicdl taber" (bl.felablf 3 de are a good indicator of dyami on-road fetfor- made on wheeis in the June edition of Bi&a grees) at the ends to t/omote unit'otm sbread' Tech. Howevet, the presumption, by Mr. ing of the a.dhesiue. The technical datd in this In farl. w? hot)? spotxsorcd a spi?s oI4' amt Akers and Mr. Price, that European roads patent file is of definite aalue to frdmebu;ldels gøLge aheel letformance tests, using strain are inlerior to roads in the USA, and that uorhing uith sbnilar methods; the generøl his aheels with the signals brought out equip\ed small flange hubs serve to smooth these tory of the ,rocess, b! J. DePai.llat «td. trans' thro gh slip ings to d Portable datalogger. rough roads, introduces questions about ob- lated here, is aLso of interest. These tests are now in lrogless, dnil Ne rløn ta jectivi§. The value of large or small flalge re\ort on the res lts in a f ture issue. hubs seems not to be part of this research. The rdea of using alumrnum for lramcs is Howevet there are interesting data included an old one, and goes back to the United in this report which, ifanalyzed, might add to States in the early 1900s. A French poster Athletics vs. The Bank Account our underctanding of wheels. from the period 1910 lo 1914 already men- The author points out that spoking pat- tions a manufacturer, a Mr Rupalley of To the Editor: terns have some eflect on wheel stiffness, Paris. with an aluminum bike, stripped of all (18.7 This letter is intended as a general com- but how imporranr these dif{erences are is accessories, weighing or y 8.5 kg lb.)l ment, but it was inspjred by the article in the left unanswered. I believe that a little infor Numerous aluminum frames were built August 1985 issue that describes a so-called mation can become misinformation. One oetween 1935 dnd 195u, including cenain revolution in front derailleurs, i.e. the might be moved to dmw incorrect conclu_ commercial models. Thus, it's not a question Bro\r,ning Automatic. sions in wheel design based on the measured of innovation. but of evolution, which allows progress, Orerthe years T have noled lhal inexperi- differences, some of which are certaiily sub us today, thanks to technical to enced athletes become obsessed with every ordinate to other opposing considerations. envision industrial production crcating com- new gimmick in cycling technology. To this, I In rhe follo\.r-up article. Mr. Flower lries pelition frames in plastic, fiberglass, carbon- say there is no substitute for fitness, cour- to put some perspective into the data and Iiber. and titanium. age, and skill born of expedencel Anyone how it fits with analytical work. ln response The 6rst commercially-practical aluminum who hac done enough racing and training to his quesrion on lateral stiffness shown in models oI several builders and innovators knows, in the end, that it is "570 bike and my book, I wish to point out that the curves were exhibited at the French bicycle trade 95% rider. " in Figure 17 are for a single pair of spokes as show in 1932. Mr PY, in particulat pre- Furthermore, I think it is a cdme against shown in Figure 18. The title under the .ented ar aluminum rrame assembled using true atl eticism to constantly inllate the cost graph fails to indicate this. Figure 17 demon- steel jcints with the aid of internal conical of riding competitively on a bike. Let's not strates that left and right tension and lateral couplings. a frame made in quantity by Au- forget that the profit motive is part of the stiffness are unequal in offset wheels. They tomobiles Delage and Gnome & Rhone. reason why oanufacturers develop aero show, for instance, that when cutting all the This frame was used on September 9, wheels, weird helmets, rubber suits, left spokes, the right spokes willnot become 1933 by former racer Marcel Berthet $35.000 bikes. and other such expeosive slack. This can be observed when disman- when he coveted 48.04 km (30.20 mi.) in gadgets. I applaud Greg LeMond for his re- tling a tensioned wheel. one hour at the Princes Park. The Delage øarks in lfinning, where he voices his de- bike weighed 7 kg (15.41b.), had a low "car- sire to eliminate the expensive advantages Jobst Brandt eenage" (aerodynamic drag), and was and to make cycling a sport where it is ath- Palo Alto, CA equipped with Duralumin gears designed by (the lete ,r/srs athlete and not pocketbook rulsrs Marcel Riffard famous builder of Cåud- pocketbook. Bob Flor.oer rerlies: ron airplanes). This performance ap- I agree that it is beneficial to improve the Thd ks to this claificatiotl that Figures 17 proached that of Eddy Merckx in Mexico and effiriency of the bike. But in compelilive cir- and 18 aillr to just a single pair of spokes, proves that the racer's "careenage" has cumstances. we must draw the line some- rather tfum to the complete spoked wheel, much more of a bearing than the aercdynam- where for the sake of fairness to all. Let's Iobst Brakdt's rtgves for lateral uheel stiff ics of the bike frame itselfl see if all this technology can give us a safer, ness d./e fiou in much better agrcerkent uith At this time, other manufacturers used more reliable, and Lss expensive mcing bike the exleirnehtal results of Pice ønd Aken. various assembly techniques, including:

'14 rvith Dural tubes. whose ends followed up by industrial production because ti\?lI small. and thar å greater reducrion of -.{viac.sere expanded inside molded lugs, the machine finishing ofjoints, and especially weight is still possible. This should lead to lur- C aminade, with oclagonal tubes the required finishing - touches, were difficult ther progress in frame construclion." ?irs rcrr,", scre\ed into exte or lugs, problems that strongly penalized this design. is ftndftablo be&use il cl?atl! a liitdtes the positioned -Hurtu, with tubes in a mold, At that same time, other techniques were q,r.slrors, sx.i, ds [ali{u? slrenEth d»d lo* d?- and joints casl over these tubes (a method perfected and exploited, such as: sign, lhal itkrest lmrneb ildrrs lodar. ''rein\.ented" by the Japanese around 1973), -C.M.P of Lyon made a frame with exter- with internal lugs that locked nally screwed joints, similar to the Caminade Yr I L.lltilltt i\ at E tlt»trl tn ttu (\1( D.rurltu d -llercier,the tubes in place by expanding inside them, solution, and Ihen made a second generation .{hlt.,: l( lu R !,St.Eh r.. f,a".l soldered -and numerous or bronze-welded frame in which the tubes were bolted and nlodels. glued to the nolded joints by a quarter-turn The forks of these bikes were oflen nude nlounting of the bayonette type, Maledrlr. Mdlnb. Ir§sioloCy. &Eirle€rinS. Arirdynalni(§ r;f aluminum, and sometimes cast in one also of Lyon, made soldered -Sabliere, piece (monobloc construction). frames, whose beautifr construction re- After World War ll. the fashion and neces- quired highly-skilled craftmanship- srt\ ul b,ctcle commuling prompted an in- Two years ago, the [adhesive-bonded crease in production of bicycle lines such as framel project was taken up again Ateliers ffi bv those of Mercier and Gnome & Rhone. Be- de la Rive and Angenieux C.L.B., with the STATEMENT OF THE OWNERSHIP MANAGE. tween 1945 and 1950, lndochina imported collaboration of Lauzier Co. to develop the MENT AND CIRCULATION OF BIKE TECH RE- QUIRED BY ACT OF OCTOBER 23, 1962: SEC- 300,000 to 400,000 copies Mercier's molded pans. and provide of 3M Co. to suit- TION 4369, TITLE 39, UNITED STATES CODE, Mecadural bikel able adhesive. FILED, oCTOBER r, 198s. BIKE TECH is pub- In 1943, the "Centre Technique de I'Alu- 'Ihe important breakthrough consisted of lished 4 limes a year at 33 Eåsi Minor Street, Em- minum" was equipped with a test bench used pressing the tubes onto internal lugs Ether maus, PÅ, 18049, publication and Seneral busimss of- until 1958 to test numerous bike frames, and than inb external ones. which reduced or fices. I . The names and address€s of th€ publisher, editor even motorcycles. On this bench in 1947, a eliminated the 6nal machine hnishing and re- and managiu editor are: Publisher - Mccul- gauge James complete strain evaluation along with fined the visual"step" of the luggedjoints by lagh, 33 East Minor Street, Emmaus, PA 18049; road tests was carried out on aluminum eliminating it. A cone-shaped fitting with a Editor . Robert G. Flower, :]:l East Miror Str€et, frames, the 6rst testing o{ its kind in the slight taper was adopted in order to improve Emmåus, PA 18049; Managing Editor , Susan world." This important work has served as the press lit of the joint and lo improve the Weåver. 3il East Minor Street, Emmars, PA lPO49 2. The owner is: Rodale Press, Inc., 33 E. Minor a base, in recent years, for calculating frame wetting of the joint with adhesive. Street, Emrruus, PA, the stockholders thereof be- designs. tube dimensions, lug designs, and Finally, a new technique has appeared with ins Robert Rodale, Anna Rodale, tudath Rodale. the choice of alloys. the Hautiprod frame, conceived by Mr. Marshall Ackernan, David R. Widenmyer, John The first ftame assembled with 'Araldite" Hautier, who, when he directed Gitane, Haberern. Robert Teufel, Mark Bnckiin, and San- adhesive was undoubtedly built by Mr. adopted the Aian frame. On this ftame. the ford Beldon. 3. The knoim tsoisis. with the collaboration of the Treh countersunk, screwed joint design ensures bondholders, rnortgrgees, ånd other secanty holders owning or holdinS I Dercent or nretaux Research 1948 Center lbr Silver in that the frame tubes are securely locked into more of the total amount o[ bonds, mortgåg$, and or 1949. The results, although very conclu- the lugs. other se.unfies ,re: None si!e, §ere not exploited commercially due to Why have we chosen, among all solutions, the bicycle "crisis" of the 1950's. to promute lhe completely glued hame? It is It was only in mid-sixties that an ltalian because we believe that this technique best of copies each issue Single engineer, Mr Falconi, presented a "screwed exploits the qualities of aluminum alloys, not duriu issue and glued frame at the Milan Tiade Show' or y in the tubes but also in the cast littings. prec€djn8 nearest to which was manufactured several years later and in particular because of the great relia- l2 nms. 6lirU dite in a mid-priced line under the name Alan. bility of glued aluminum structures. A, TOTAL NO, COPIES S€lt, 1984 The tubes, of 2 millimeter thickness, werc It is also the lightest solution: The weight (Nei Press Run) Aus. 1985 Ausust 1985 threaded and screwed into the external of a whole frame with fork does not exceed 11,760 10,850 joints \rith Loctite glue lo avoid loosening 1.800 grams (3.96Ibs.)l lt also allows great B, PAID CIRCULATIOiI of the threads and to lock up the entire joint. manufacturing flexibility: Small or medium- l. Sales thmugfi d€alers and This iranre !.ras distributed by Gitane in sized production mns require little invest, carriers, srreet vendors 1,145 r,æ0 years. production l'rance for several ment, while full-scale can take ad- 2. Mail S{bsdiptbl 7,gil) ?,672 The experience in gluing aluminum alloys vantage of many of the fabrication steps. C, TOTAL PAID autorno- acquired in aeronalrtics, railroads, CIRCULATION biles. hdustrial vehicles, and skis inspired us 6um of Bl and 82) Boisis idea in result' to reconsider the 1973. D. TREE DISTRIBUTION BY 'tEdilor's nole: A rulort on this tesling uas pub in8 in the construction of a prototype wilh MAIL, CARRIER OR Lished (in Frcnch) ir1 lhe t?chnial journal Reyue Ateliers de la Rive and a frame builder from OTHER MEANS de l'Aluminum, October 1919, 89-95. The Givors. Mr. Miosotti. baEes SAMPLES. attile. litled"M(; r. des Elfo se Mafthc Nor To obtain a light frame as rigid as a steel COMPLIMEMARY, AND ,mle sat ul Cadft dc Birlelte," b Francois Flu. OTHER FRf,E COPIES one, with snug frtti[gs and large gluing sur- sin, conlains th€ English summatt: .folLatuing E. TOTAL DISTRIBUTION faces, long molded external lugs were per- "'lhe Centre Gchnique de I'Aluminum has car (Sum of C e D) forated and trirnrned to lighten them to the ried out measurements of the importance of T COPIES NOT e1e. and to avoid the look of "plumbing" stresses in certain joints of an A G5 bicycle DISTRIBUTED ma.hined good frame und(r stdric lnads uf Iv8 lbs. The maxi- Joinl. and inlernally for fi1. l. OIfrce us€, left ov€r, mum latigue was recorded in the fork with a fig' Thanks to Miosotti's design, this frame uiåccounted, spoiled after ure of 7,111.6 psi. Dynamic measurements made \ras beautiful. Several of them were made: prhtirs 1,563 r.4s8 eitherat the testing stand or actually on the road 2. Return kom Ne§,s Agents 390 430 most of these are still rolling today, includinS shos rhar the curre"pnnding overload<.an be rn one rvhich was used by Cyrille Guimard in lhe neighborhood of 100? of the static values. G, TOTAL (Sum of E, Fl and F2) 11,760 the Paris-Nice race, with a stage victory to The conclusion to be dra*n of such tests is that 10.850 its credit. H<.rwever, the prototypes were not the value o[ stresses in certain points is rela-

15 DUPONT'S NEW TWISII' IN COMPOSITE tr'IBERS: The Dupont Compani,, wel-kno\\,n to cyclisls as the ntaker oI l{evlar high-tensile fahrics and Nomex honeycornb, announced plans to becone a fullservicc supplier ofall the components needed to produce fiber composite struc tures. This includes adhesives, resins, yarns, woven fabics, and design,,testing senices, ac cording to Mike Bowman, director o[ Dupont c compoiitcs group. Dupont recentlv purchased newsline the carbon-fber production facilities of Exxon Enterpriscs (source of the ill,fåtcd Graftek G1 bikes of lhe mid-70's), and is now developing several low cost Kerlar and carbon hybrids. If you are designing hicycle frames or other components that use struclural composites, should ,.Access -vou probably be in touch with DuPont. I.'or a copy of Dupont,s Cuide'. tå composilc materi- als, or a subscription to the KEVLAR UPTAIE newsletter. contact Jim N,londo, Recreation I)roducts Croup, DuPont Composites Venture, Ccnter Road, \\iiningron. DE 19g9g. . . . CLINIC ON COMPOSITES: Tbis summer, IJupont will sponsor frcc workshops to demon stmte fabrication meLhods for composite structures. Hand lay up, vacuum bagging, and fiiamcnt winding are some of the procedures to be shown. The workshops will be held at the Expcnmen- tal Aircralt Show in Oshkosh, Wisconsin, August 1 to 8, 1986. For details, contact Exp;rimental Aircraft Association Headquarterc, Wiftman Airield, Oshkosh, lVI5490il; phone 414 ,126 4g00.

< SHIM^NO INTRODUCES INDEXED SHIFTING TO THE 600 EX LINE: The Shi mano Index System (SIS) that was introduced in the New Dura-Ace linc last year has no§, becn applied t, rear derailleurs and shift levers in Shimanu's 600 Ex rangc. Faster and easier shifting is possible with the SIS system because finc adjustments of the shift lever are not needed (see April 1985 Bråe ft.r). The new 600 IJX shift lever (Model SL-6208) was designed for a Iishter touch than the New DuIa-Ace shifter, and also features an improved ball dete-nt and an ad]ust ment spring. The new 600 EX rear derailler_:r (Model RD-6209, see photo at left) has several improvements over the old mode1, including rubber O-ring seals on the pjvot arm bushings. And most important, according to John Uhte, Assistant Technical Manager oiShimano Sales C"orp., is that all Shimano freewheels now on the market are compatible with the SIS system. If you,ri not ,.SIS'-, sure yourve got a newer, compatible freewheel, look for the word next to the teeth number stamped into the freewheel's cog. Other new products from Shimano include an ALL-SPORTS PEDAL: The Shimano Model PD-T100_(see photo at left) was designed foftriathlalons, all-terrain bikes, and general al1 around sports riding. With the same sealed axle design as the Shimano 600 pedal. the new pedal .an be ridden with cleats or. by slipping in the flat sole plate, ivithjogging shoes or sneakers. Also new is the ECONOMICAL BIOPACE CRANKSET: the Shimano Moclet FC-B124 is identical in aI dimensions ta the regular Biopace, but is made by a less expensive clie-casting process rather than by forging. The econo-Biopace will be availabie with either 170mm or 175mm cranks in the 28T/38T/48T gear range. March 1986 is the expected date for availabilitv of all these Shimano products. (Shimano Sales Corp., 9530 Cozicrolr Ave., Chatsworth, CA 91311).

< ?HE SCOTT SUpnnBnA,fp, In June 1985, the Scott/Mathauser Corp. released the pro- duction version of a radically new caliper brake system (see photo at lef[). A prototype was ,,oversize,' reviewed in detailin December 1983 Biåu lzcr. The brakes' caliper aims, måchined from solid aluminum, are said to be exceptionally stiffand t\i,ist-resistant, but weigh Iess than one ounce each. The symmetry ofthe single-arm pivot is designed to avojd the centering problems of sidepulls. The brake's reach is adjustable from 39 to 57 mm, via a slofted mounting plate, and can be extended to 63 mm with an extender bolt. The most ultimate aspect of the ne$ Scott brake set may be the price: in the vicinity of 9200 retail. Framebuilders take note: For proper clearance in mounting the Scott Superbrake, you need to pay attention to a feN special dimin- sions on your fork c.own layout. Contact Ed Scott at the followjng address for sp;cific details: Scott/Mathauser Corp., Box 1333, Sun Valley, ID 83353 (208 726-S432). REFLECTM MATERIALS UPDAIE: f)o cycting vests and reflecto^ really make night time riding any safer? Committee !'-22 on "High Yisibility trIaterials for Safety', of rhe American Society for Testing and Materials (ASTM) worries about this question, and will meet in January 1986 to discuss possible solutions, such as new tests and standards for reflective materials. Their concern was prompted partly by the experiments of Richard Blomberg of Dunlap Associ ates, which found shortcomings in the performance of conventional bike reflectors and reflective fabrics (see February 1985 Rike Tech. The F-22 committee has already issued Standard F 923, "Guide for Understanding the Properties of High Vlsibility Materials for Individual Safetv.,, This document contains many hard-to find definitions and practical explanations of the euniepts rn volved. For more information on the AS1'M Committee F 22 meeting, contact R. Blomberg, Dunlap Associates, 17 Washington St., Norwalk, CT 068i4 (203 866-8464); or Robert Morgan, ASTM (215-299-5s05). A Man lactured bv \!/ rr nevruoros riMrrED. EnsrJnd < REYNOLDS ANNOUNCES 501 SL DOUBLE BUTTED TUBES: A ncw CrMo tubeset designated "501 SL" rvas on display by TI Reynolds at the Pa.is Cvcle Show in October. The 501 SL has double-butted main tubes and, for the first Ime in Reynolds trMo specification, "wide oval" taper gauge fork blades and light gauge seatstays and chainstays. The alloy has an ultimate tensile strength rating of 116,000 psi, and Reynold's claims it can be bmzed at tenlpera- tures up to 2000 deg F with minimal post-bmze loss ol strength. Reynolds is aiming the 501 SL tubeset mainly at manufacturcrs of sporl bicycles in the mid-price range. Contact John 'l'cmple at Slurmey-Ar.her of Amcri, a. l0l4 Ca-olinr Lrrrve. 11.60185 rl 800-32:t vl94).

16