Belt-drive Bicycles

Stunning drive-train photo from Fixie Inc

Belt-drive bicycles are machines whose chain has been replaced with a rubber belt similar to those used on car fans. They are specifically built as the drivetrain’s teeth sit into the cogs unlike a standard chain which receives the cogs’ teeth. The frame is also a specialised affair which must have a complete break in the rear triangle (seat-stay, chain-stay and seat-post) to allow the unbreakable belt to be fitted.

You can search for this topic anywhere and the first thing you will see is that this technology is not new. Well, The Inquisition doesn’t want to be left out so it should be pointed out that Archibald Sharp classic “Bicycles & Tricycles: A Classic Treatise on Their Design and Construction” from 1896 discusses belts in rubber and steel as transmission possibilities.

Belt-drive bicycles might be big and soon. But also, they might not be. Either way global cycling market leaders and Lance Armstrong sponsors Trek are taking a punt by launching two commuter belt-driven models in 2009. One is singlespeed, the other is hub-geared; the latter is probably a more exciting possibility for most cyclists.

The (potential) Benefits

Without needing the approximately 3000 individual parts of a chain these belts are easier to maintain. They will not give a greasy right ankle on your pristine linen trousers. And they are a fair amount lighter, averaging 70g where a chain might be 300g.

The (Again, Potential) Drawbacks

Rubber bands could be prone to stretching and slipping which would be detrimental to pedalling efficiency. They should fine though as motorbikes which use these belts don’t have these problems, Carbon Drive Systems, who produce the belts for Trek, have integrated carbon fibres into their system for added security.

The biggest drawbacks are having to open up a gap in your frame to make a replacement, maintaing the appropriate tension and correct alignment.

So, what does it look like (when ridden by some guy with blinding shoes)? Take a look for yourself:

For More info:
Bicycle Design Blog
Carbon Drive Systems
Fixie Inc
Trek Bicycles District
Strida Folding Bikes
Ellsworth (The Ride model)

This article was posted on Friday, December 12th, 2008 at 06:23.
It is archived in Bicycles and tagged Alternative, Bicycles, Engineering.