Perhaps the most fascinating products I’ve seen at the show so far are the Spot belt-drive bikes. Spot brought 40 belt drive bikes to the outdoor demo and folks were riding around in them all day in the desert conditions. The feedback was very positive so I paid Spot a visit to get a deeper understanding of this new drivetrain.
Folks have been dreaming about belt-drive for years. It has never come to fruition until now since a suitable belt has not been available until last year. Josh Ogle from Jericho made a big splash a few years ago when he showed off to Interbike with a belt-drive bike. But, the drivetrain was not reliable because there was no available belt ready to take the forces of the bike. But finally, a company called Gates Corporation released their belt drive system for bikes called the ‘Poly Chain Carbon Belt Drive System’
More info: http://www.gatesprograms.com/carbon/
The advantages of a belt drive system are low weight, noise and maintence. The weight of the belt is about 55 grams while a typical chain of the same length is about 255 grams. The system should be quieter as it experiences no squeaks, pops and rattles. And finally, the belt never needs to be oiled. It is more durable than a chain and never stretches. It’s lifespan is around 8000 miles.
On the minus side, no derailleur is possible with a belt drive so applications are limited to singlespeed and internal gear hub systems. Another difficulty is the frame needs to be specially designed for this system and allow a break in the chainstay. Since the belt cannot be broken, the frame needs to allow inserting of the belt in the chainstay. Finally, a belt drive system like this limits the user to very few sources for front and rear ‘belt wheels and cogs’.
One of my big concerns about a belt drive system is power loss. If I lost 10-20% of my power due to drivetrain friction, that would be a deal-breaker for advanced mountain bike riding. My test riders however could not detect any power loss in the 30 minute test rides. And more important, Spot Bikes hired and independent company to compare their belt drive drivetrain with a standard chain drive system. The test involved using a motor connected to a Powertap power meter on two bikes. The findings were there’s no power differences between the output of the two systems. Please see the document below for an excerpt of the study.
Ok, but where’s the bikes? If you are singlespeeder, 29er, commuter, cyclocrosser, you have reason to rejoice.
The bikes are beautiful and they are nicely spec’ed. Expect more details coming soon.
Longboard – singlespeed 29er
Black and Tan – singlespeed cyclocross