Ever 10 years or so a gimmick comes along to sell bikes that is supposed to be the next best thing; Elliptical chainrings spring to mind. Are belt-driven bicycles a flash in the pan or a revolution in cycling? My short answer will be that belt-driven bicycles will probably become popular for pedestrian cyclists, no pun intended, but not for high end racers.
Why Belt-Driven Cycles will likely become Popular:
For the non-professional or non-aficionado rider, belt-driven cycles could be very attractive. The belt does not need lubrication, ever. A side effect of this is that without lubrication, there is no chance to get black chain marks on your brooks brothers or Levis. It is argued that they are quieter than chained-bicycles, although my fixed-gear bike is virtually silent with a chain; this might have to do with the switch to a single gear pattern. It is argued that there is no maintenance needed for the belts, but this seems to be a self-fulfilling prophesy: if a belt fails, you replace it, there is no way to fix it. Others say the operation is smoother with a belt because of the wide gears and the noise-dampening properties of the rubber. Belts can't rust and they are supposed to last longer. Previous belt systems were prone to slippage and loosening after a long period of riding. The new, carbon-fiber-and-rubber belts are quite strong and stretch resistant. If Harley-Davidson thinks belts are bad-ass enough to use on their motorcycles, there is clearly no issue with the strength of belts. In sum, the ease of maintenance and lack of lubrication will be the biggest selling points of this system.
But wait, its Not All Roses:
There are a few disadvantages to the belt system. Right now, they are not as widely available. Trek Cycles is offering a number of bikes with belts, but they are not yet widespread. The gears that engage the belt are plastic and therefore not as strong and robust as typical metal chainrings. Another problem is shifting. There is no derailleur-style shifting possible. Any change in gear ratio must be through internal hubs. This is not necessarily a downside per se, as internal hubs are cleaner and robust, but they are not as widely available, again. Finally, and sadly, you cannot retrofit your chain-bicycle to a belt-bike. You know how you need that chain tool to take your chain off your bike because it goes through the back triangle? Yeah, belts don't come apart. This means that if you want to try and really evaluate a belt bike, you have to buy one. Ouch.
So What's Wrong with Chains?
There are clearly some things that nobody likes about chains. They are dirty, greasy, can stretch, need special tools, and can rust. On the other hand, they are very efficient mechanically, often measured in the high 90s percent-wise. Chain stretch doesn't happen over night, either. You need to log lots of hours before you will see a drop in performance with your chain. This mechanical advantage hopefully insures the survival of bicycle chains in racing and performance bicycles. I have heard a lot of people commenting on the feeling of "really feeling the bike" i.e., your pedaling is efficiently transferred into forward motion. I got the same sensation when I started riding fixed gear. Might it be that these people are excited about fixed gear feeling, not just the belt? Who knows.
CNN's Story on Belt Bikes
Blog on Belt with lots of Comments