Another Run at an Old Favorite

September 16th, 2007 by Brad Quartuccio

Here’s another run at an old favorite – belt drive. For reasons of weight savings, aesthetics or just to try something different Carbon Drive Systems is bringing a belt drive system to the table. Every so often someone out there tries to outdesign a bicycle chain system be it with belts, hydraulics or shaft systems. This is the latest try at an old game.

The CNC machined belt-ring and cog are matched to a seamless, polyurethane and carbon belt for a total reported weight of 180g, which if true is quite amazing. Of course, the seamless belt makes a bike with a split chainstay or seatstay assembly a necessity, with Spot making the first run of bikes with a split dropout as shown.

A few years back on-again/off-again singlespeed maker Jericho introduced similar bikes and a belt drive system that as far as I can tell hasn’t caught on…

The fundamental question remains; why? Potential losses of efficiency are of far more concern than drivetrain weight. At least they should be. A properly lubricated modern chain system is remarkably efficient – theoretically and in use, nothing much comes close. And other than on the scale, efficiency always wins.

7 Responses to “Another Run at an Old Favorite”

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1 Fred on Sep 17th, 2007 at 12:43 am

Why? Lower maintenance and no grease marks on clothing or legs. Which is important to infrequent or casual riders and commuters. But you knew that already. Less efficent, no doubt, but how important is that at 8 mph?
2 Arleigh on Sep 17th, 2007 at 10:39 am

I am interested in trying it for say a commuter bike. I don’t think I would take a rubber band mountain biking.
3 Fred on Sep 17th, 2007 at 10:42 pm

You wouldn’t take a rubber band mountain biking. What kind of “chain” do you think is used on many camshafts in auto engines?
4 Arleigh on Sep 18th, 2007 at 8:06 am

Yes, I understand a lot of auto engines and many machines use a belt drive but they also aren’t getting dumped on the ground directly on that belt. Abused with sand/dirt/etc. They go one direction and nothing is stuck in that process.
5 Tim on Sep 20th, 2007 at 4:13 pm

Aren’t many motorcycles belt driven? I see lots of “choppers” that have a large exposed belt drive.
6 The Moose on Sep 26th, 2007 at 7:07 am

Most motorcycycles are belt driven now, especially the customs. Belt drive doesn’t have to be less efficient-they aren’t “rubber bands”. Next time someone out there replaces a belt on a car try to stretch it by hand. After failing at that try by holding it down on the floor with ones foot and pulling with both arms and back muscles.

I’d wager that no one this side of an NFL lineman can stretch it at all.

Could the added mech. adv. of pullies and leg muscles do so? Maybe, and I mean maybe.
7 Arleigh on Sep 26th, 2007 at 8:12 am

Again - I’m not questioning if a belt will last or how strong it is. I’m questioning the durability for off road exposed use. How often do you get a rock or log hit your chain?

Another Run at an Old Favorite

7 Responses to “Another Run at an Old Favorite”

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