FRAME TECHNOLOGY The Return of Reynolds Reynolds Technology has a history that stretches back over a century with much of it in the motorcycle industry as the supplier of steel tubing for frame manufacturers. Having left the industry a while ago, it is now planning a return with some high-grade material that fits with its image as a high-performance engineering company as Peter Jones reports. For something as handling of the infamous Honda its material technology for the apparently mundane as steel RC181. tubes it manufactures today. This tubing, Reynolds Technology has Reynolds’ backing for its frame approach has certainly paid a somewhat celebrity status in building went as far as offering dividends in its increasing share motorcycle racing history. Bronze an annual frame repair service at of the cycle frame market, and its welded Reynolds 531 frames the Isle of Man TT for many ‘air hardening’ steels have played were the de facto choice for years. a vital role in improving cycle many top racers up until as Along with many other British frame fatigue life in line with recently as the 1970s. companies, Reynolds suffered toughening EC legislation. Introduced as a manganese badly in the 1980s and through The modern evolution of the alloy tube in 1935, Reynolds 531 into the 1990s from the general Reynolds 531tube is the 631 tubing was the stock in trade for decline in the British alloy, along with its heat-treated motorcycle frame builders manufacturing base until it was relative 853. The 631/853 alloys including, of course, the famous subject to a management buyout. have been developed to suit ‘feather-bed’ frames of Norton. That same management team, modern manufacturing methods Reynolds was well known in its led by the ever enthusiastic Keith and can be TIG welded without own right for manufacturing Noronha, is still the basis of the the problems traditionally motorcycle frames, with perhaps company today, with its associated with the previous 531 its most famous frame builder, manufacturing roots remaining in alloy – although they can both Ken Sprayson, being responsible Birmingham. still be bronze welded without a for making frames for many top In the last 10 years Reynolds problem. racers, including one for Mike has invested significant time, The cold drawn, seamless, air Hailwood to help cure the money and effort in developing hardening steels gain their 28 • April/May 2010 • Moto Tech www.racetechmag.com FRAME TECHNOLOGY stress in the material exceeding tubing. In the case of motorcycle the material’s UTS or Yield frames, it is seeking to re- strength at the areas of highest establish itself. Other industries stress. currently developing lightweight Graph 1 below clearly shows structures and components with the typical relative strength of Reynolds are from industries as 631 in the weld area, compared diverse as speed skates, to the Reynolds 525 Chromoly lightweight car chassis and tube joined by the same suspension components and technique. Whilst the yield sports wheelchairs. strength through the 631 weld The embarkation by Reynolds joint remains above 800 MPa the into new markets has neatly yield strength in the equivalent coincided with a resurgence of Chromoly joint is reduced to 550 chassis building for racing MPa. The advantages of such a motorcycles, initiated by the strong joint for a frame builder creation of the new Moto2 class are clear. for the World Championship and In addition to the advantage of national series. Classes such as the air hardening properties, ThundersportGB, supermono Reynolds also offer ‘butted’ and classic motorcycle racing variants for its 631 and 853 also offer good opportunities for tubing. This process, invented by tubular frame builders, Reynolds in 1898, no less, uses a predominantly where the racing die and mandrel to manufacture is not limited to production tubes with a constant OD based race bikes. coupled with a variable ID. This It was with these markets in enables the designer to have the mind that Reynolds approached material where it is more needed a number of development – at the butted joints – whilst the partners in early 2009 who were strength at a welded joint centre of the tube can have a making tubular motorcycle without requiring water thinner wall thickness. If does, of frames. The aim was to obtain quenching to obtain a stronger course, offer another possibility feedback on the suitability of the but ductile bainitic phase of to the frame designer – flex proposed thin wall tubing direct material. This quality is vital in without failure. from frame builders, and also to producing a high-strength establish the range of tube material structure right through Sizing up the motorbike market diameters required to support the base material, heat affected Having firmly re-established itself the market. The three zone and the weld itself. The as a supplier of premium grade development partners who inherent strength at the weld tube to the cycle industry, responded enthusiastically were joint enables the use of thinner Reynolds has now embarked on Davies Motorsport, Tigcraft and wall tubing reducing the risk of developing new markets for its Bottpower. Davies Motorsport builds and races classic Honda twins in the Material strength through cross section of welded joint British Classic Racing Motorcycle 1,400 Club (CRMC) championship. Whilst the tubular TAB and Drixton replica frames it used 1,120 were already reasonably light, the opportunity to remove a small but significant proportion of the 840 bike’s weight was enough to interest the company. Additionally 560 it was looking to move from the traditional route of bronze welded 525-BRAZED frames to TIG welding in order to 525-ER70 TENSILE STRENGTH MPa TENSILE STRENGTH 280 631-ER70 improve joint durability and also 853-ER70 lose weight from the frame. This 853-NO FILLER fitted perfectly with the 631’s air 0 Tube Metal HAZ Weld Metal HAZ Tube Metal hardening properties already outlined and thus the world’s first CROSS SECTION OF WELDED JOINT Reynolds 631 motorcycle frame Reynolds 2007 was born. ➟ www.racetechmag.com Moto Tech • April/May 2010 • 29 FRAME TECHNOLOGY So pleased were Reynolds with presented a perfect opportunity the results that showed its frame to get some forthright feedback weighing in at 6.9kg, a full 1.5kg as to how the 631 tube ‘worked’ lighter than the previous one, for a frame manufacturer. that it was taken to the 2009 Having overcome some initial Manx GP for public display. scepticism of working in thinner Everyone who picked it up wall tubing, using sample pieces ‘overlifted’ it and was very in project frames, Reynolds surprised by the weight, or lack provided Tigcraft with sufficient of it. material for the manufacture of a The Drixton 631 frame is number of frames. The first of currently in the process of being these, a Moto2 type frame for a built into a complete Honda 500 Triumph 675 engine running in twin and will compete in selected the Thunderbike GB series, was rounds of the 2010 CRMC completed just before Christmas Series. The 631 TAB frame was 2009. built in March and will also Dave was extremely pleased compete is selected CRMC with the resulting frame and has rounds and some races in since also built a 631 tubed Continental Europe. frame for a Suzuki SV650, at a The Davies Motorsport project mere 7kg, and is currently also provided the first embarking on a Moto2 frame opportunity to analyse a frame which will carry a Honda with Penso of Coventry, CBR600RR engine and a Reynold’s CAE partner for ‘Moto3’ project using a Yamaha lightweight structures. Having YZ250 motocross engine in a been provided with the frame as lightweight tubular chassis. All CAD data and a set of load cases the bikes will be out competing having been agreed Penso went on track this year and the about meshing the model, feedback from riders will be applying the load cases and invaluable to Reynolds in terms checking the stress levels in the of developing the tubing range. new frame, whilst comparing its Bottpower is a partnership stiffness to the thicker walled between David Sanchez and Jose variant it had replaced. Contreras in Spain. Having seen The results showed that 1) the Bottpower’s Moto2 project on its predicted levels of stress were all website, Reynolds contacted well within 631’s yield strength Sanchez to see if he would be and 2) there was a corresponding interested in using 631 tubing for 10% loss of frame stiffness by his project. As with Tigcraft, moving to a thin wall tube sufficient tube was supplied to without any change to frame enable Bottpower to build a Bottpower has been ideal for Coventry geometry, as had been expected. number of frames, mainly with a feedback. Tigcraft hand builds University Penso then strategically added a view to developing the initial frames using a jig, hand butted Supermono small amount of tube to the design to a lighter weight version joints and bent tubes for the (top) concept frame in critical areas to as the project progressed. main spars. Bottpower works in and (above) demonstrate that the stiffness The Bottpower Moto2 project Solidworks CAD and has the the bike being could be regained with only a is extensively covered on its tubes laser cut off CAD models, tested at small addition of weight to the webpage with the first frame into short, straight tube lengths Mallory Park frame. Unfortunately the rules having been built. The bike is which are then welded together within classic racing prohibit now a rolling chassis, rapidly in a jig. The two different routes changes to frames, but it was an progressing towards being a to the same result have provided excellent opportunity to show complete bike for this year’s excellent feedback and to date what could be achieved using Spanish CEV Buckler series in no problems have been reported.