HAYES TO MARKET CHAIN-DRIVEN GEARBOX SYSTEM–OCT 5

HAYES TO MARKET CHAIN-DRIVEN GEARBOX SYSTEM–OCT 5

By: Richard Cunningham
Tuesday, October 5, 2004


Hayes Disc Brakes announced that it has the exclusive rights to manufacture and sell the PeteSpeed gearbox that has been raced by the BeOne downhill team this past season. The PeteSpeed patented ?gearbox? is actually a small derailleur that is packed into machined-aluminum housing, mounted in the frame near the bottom bracket area. Inside the box, a freewheeling sprocket, driven by the crank arms, powers a close-ratio road bike-type cogset. A compact set of jockey pulleys is fixed to the crank-side sprocket which slides back and forth on the bottom bracket shaft to shift the chain across the cogset. A standard cable actuates the shifting.


Honda has patented a similar system for its RN01 downhill bike that reportedly has been in service with the team for much of this past season. There is no big secret to be revealed inside the Honda or the PeteSpeed transmissions?they are really just a derailleurs in a box. The PeteSpeed/Hayes system, however, does offer downhillers a couple of big advantages over the conventional external rear derailleur:

1)Anytime shifting: because the freewheel is at the crank, not the cogs, as long as the bike is moving, so is the transmission?which means that you can shift whether you are pedaling or coasting.

2)Precise drive-sprocket placement: the final drive sprocket can be placed close to, or concentric with the swingarm pivot, which helps to remove pedaling torque from the suspension action.

3)No more flailing chains: a derailleur in a box has a short chain that cannot derail easily. Conventional external derailleurs are weak chain tensioners that let the chain flap all over the place.

4)Say goodbye to muddy cogs: Only the final chin drive and a couple of sprockets are exposed to the goo and dust?and a heavier chain can be used, because it does not have to shift.

SO, WHAT?S BAD ABOUT IT?
Weight?it has to be contained inside a strengthened housing that is bolted to a frame, so it will be heavier. And, it will not cover a wide enough range of gearing to make a true mountain bike transmission in its present layout. Another disadvantage is that the small-diameter sprockets inside the PeteSpeed transmission are subject to much greater torque loads than the larger-diameter sprockets of a standard system. This will undoubtedly lead to accelerated wear of the sprockets and chain inside the PeteBox.