I've been thinking a lot about belt drive mountain bikes again, and after checking into it here, I see I have not posted on the subject in almost two years. (You can read the full rant here)
Interestingly, the case of belt drive systems for mountain biking seems to be a case of "the more things change, the more they stay the same". At least, the reminders from my posting in 2008 would indicate as much. Let's take a closer look........
Back then, I wrote the following:
The belt drive system for bicycles is being developed by the Gates Company which does all sorts of belt technologies for motorized vehicles. They were out at Interbike last year, (2007), en force to answer any questions and to observe first hand a real world demonstration of the "Carbon Belt Drive System" performance. After a quick briefing by the Gates folks, I got on board a Spot Brand bike and took off on the Demo loop at Bootleg Canyon.So, as you can see, issues plagued the system from the get go. Noise was common. I heard it. Everyone within earshot of a Spot in 2007 heard them. Then there were the ratcheting problems, and worst of all, breakage. Yes- There have been revisions. In fact, I mention one back in my 2008 post:
On a steep up, I heard a very loud "pop" and I thought I was going to crash because of a belt failure, but I didn't. I rolled on. At the Spot Brand tent, the Gates folks were telling me I "ratcheted" the belt. This is when you essentially get the belt to slip one tooth over on the cog or more. I did that and that was the loud "pop" I heard. With the belt tensions on the verge of being too tight for the bearings on the hubs already, Gates had to go back to the drawing board for a revision for this year.(2008)
What they did was to specify a larger "chain ring" and rear "cog" size with a slightly reduced amount of tension on the belt. The larger "cogs" would increase the number of engagement points and hopefully eliminate the "ratcheting" problems. I'm not sure if this also addressed the many complaints of noise in the system from 2007 Interbike riders, but it may have.Okay, so they fixed the ratcheting problem and reduced pre-mature bearing failures at the same time. Great. Or wait a minute..............did they? Let's fast forward to 2010 and see where this belt drive business has progressed to.
A cursory reading of this thread on mtbr.com's Single Speed forum shows that in 2010 folks are still ratcheting belts, still getting noise from belts, and still having issues with hubs from high belt tensions, (which Gates seems to have re-instated since I last looked into this two years ago). Now the solutions being suggested range from "belt specific" frame designs that feature heavier, stiffer chain stays, to installing "snubbers" to keep the belt from wandering and ratcheting on the Gates specific cogs, which by the way, have increased in size yet again since 2008.
Okay. Those are the facts about belt drive on mountain bikes in 2010. It seems as though not much has changed about the actual performance aspects of belt drive mountain bikes since 2007, but a lot of solutions have been thrown at the system to remedy the problems folks are experiencing in the field. I still see and hear about failures: from belts out and out breaking, to noises, ratcheting, and being damaged. It seems as though much has changed, but the outcome remains the same.
Belt drive systems are expensive, finicky, and not proven. There are too many failures for the small number of units being actually mountain biked in comparison to chain failures per mountain bike. I don't think Gates could refute that with a straight face.
They would rather you focus on that "greasy, noisey chain". That thing that is imminently reliable, easy to maintain, cheap, adaptable, and works even to single speed your geared bike. No, they would rather have you focus on the fact that belts are lighter, and, ("if" they run a full life), will easily outlast a chain's lifespan. You know, instead of a chain that is easy to repair on the trail, strong, and can be found almost anywhere. Not to mention the fact that belt drive systems are "cool", never mind the fact that you must run certain sized cogs which are hard to obtain and may not clear your chain stays. (Ventana display at Sea Otter 2009, anyone?) You know, not like a nasty chain drive, which has so many variations on cogs and chain ring sizes that it makes your head spin to have to choose one set. I mean, who needs that?
Who does need that?
I'm raising my hand high. How about you?