> > Would take a belt drive first, then shaft, then chain
> 
> I don't recall seeing any belt-driven bikes in top-end 
> competition (or maybe I did, I just didn't know they were)
> 
> Superbikes have to be basically show-room models, ie modified 
> production, and most bikes are chain. Therefore ....
> 
> But MotoGP are purpose-built racers. Hmmmm
> 
> http://en.wikipedia.org/wiki/Motogp
> 
> Didn't see it mentioned there but MotoGP bikes can spin the 
> tyre on the rim, maybe the same is true for a belt, and a 
> chain is the best transmission method


Belt would be more efficient than chain, so that would be an advantage.

The bits needed for belt drive are usually heavier than what's needed for
chain, so that'd be one reason for sticking with chain.  (Shaft drive is
heavier again)

Probably the main reason is you can change drive ratios quickly with chain,
swapping out a sprocket isn't hard.  The sprockets are often aluminium
(titanium wouldn't surprise me) for less weight.  They don't last very long,
but they don't have to.

Tony

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