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Two Group 6 race bikes managed to break their gear selectors while using AF Rayspeed Clo5e Ratio boxes at the Mallory race track in March. Both of the bikes concerned are in the 40-45bhp region and were on the track when the failures occurred. AF Rayspeed’s product testing had involved a season’s racing in a Group 6 engine (approx 35bhp) and a 4500mile hard road test in a 28bhp engine, plus several unusual event tests (slamming the bike into first gear at 50 and 80mph etc.)

Based on that experience, AF does not believe that fast road use in 30bhp engines would be likely to result in a failure (one of the Group 6 race riders is still running a Clo5e Ratio in his RB25 road bike and is 3000 miles in). Since then, AF has been working alongside the manufacturer to inspect the damaged gearbox from the race bikes. They have found the cause of the failure, assessed a number of design solutions and organised production of a replacement selector. Based on the previous testing, they reiterate the point that they do not believe there is an immediate danger in running the gearboxes in road bikes. On that basis they intend to continue to run the Clo5e Ratio boxes in their own bikes, until the replacement selector is available. As soon as the new design is available they will offer to replace all the original design selectors with the new version. To that end, they will require the original selector back in exchange for the new selector, or alternatively you will be able to purchase the new selector and get a full refund on the purchase price when they receive the original back. The manufacturer has placed a high priority on this new design, allowing it to jump the normal production schedule. AF expects the replacement selectors in circa the beginning of June.

Here is a brief explanation of the design change: picture 1 shows the original design of the selector compared to the new design (picture 2). The weak points in the original are the reliefs at the base of the selector legs. In the new design shown in picture 2 you can see the reliefs have been filled in, and where the selector legs join the selector ring there is now a larger radii. The diameter of the centre of the selector ring has been increased and the metallurgy has been altered. These changes increase the integrity of the selector ring, reducing the focus of the stress points, increasing the material thickness and increasing the material core strength. AF will also supply shorter gear pawls with the new selector to accommodate the increase in selector ring diameter. Initially these may be modified standard pawls, but will be manufactured to spec in the future.