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I am completely new to the concept of belt drives and, when doing some initial research, the Wikipedia article on belt-driven bikes says that they have the disadvantage of

Problems in snowy conditions (up to complete inoperability in some cases).

Has anyone had any experience with snowy commutes on a belt-driven bike supporting or refuting this claim?

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5 Answers 5

It depends

Belt drives require some mechanism to prevent the belt slipping off of the sprockets sideways.

  1. Early generation belt drives have guides on both sides of the sprocket to keep the belt from sliding off. This can definitely lead to snow, mud or other debris getting trapped in the sprockets, getting packed in tighter with every revolution, and eventually rendering it inoperable.
  2. Later designs started compensating by adding mud ports, a guide on only one side of the sprocket (with other guide on the other side) and other mechanisms to allow snow or mud to be squeezed out of the system.
  3. The most recent design has a guide that runs down the center of the belt instead of on either side (so the teeth on the belt have a gap in the middle), which should squeeze snow or mud out the sides of the sprocket and belt. From what I've heard, this is supposed to be the most difficult to clog design.

(doing a little research, number 3 is the "Gates Center Track" that just came out at Interbike 2011 and the bike I saw with it was probably one of the first production bikes of that model off the assembly line)

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There is also the temperature issue itself. The belts get stiffer as the temperatures drop and become increasingly less efficient. –  Chris in AK Nov 17 '14 at 22:03

The belt drive on my Srida gathers lots of wet snow, making it completely useless throughout the entire winter. In addition, if the temperature is around 0 degrees, the bicycle parts are prone to icing, which is the major problem for the belt drive too.

See also another customer review

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I've never ridden one but the Carbon Drive Systems website states that:

The patented sprokets contain Mud ports that shed even the worst type of debris. Not even snow or mud will slow you down.

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In theory, since the sprockets are so wide, and the belt lacks holes, snow/mud that gets between sprocket and belt will be packed into the notches and could build up if conditions are right. This could build up to where it locks the belt (or damages it, if the rider tries to force the thing), in the worst case. In any case, it's not going to make pedaling any easier.

I was just reading where truck off-roaders have a lot of trouble with mud in their serpentine belts, in some cases damaging the belt or the bearings of the generator or idler.

No experience with bicycle belt drive, though, in any conditions.

Added:

I do notice, in the belt tension thread, that the front sprocket has large holes in it and, one would expect, would not have much trouble with snow/mud buildup. The rear sprocket (in the image presented) is not seen well enough to say if it has holes in it, but it looks like not -- at least not as big as the front. Other bikes may be different, of course.

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I have been riding a Gates CDC (not Centertrack) belt drive for almost a year now. I have ridden my bike in various weather conditions and temperatures ranging from over 90℉ to under 0℉. I have ridden through a variety of snowy conditions, including a foot-and-half of fresh snow on a few occasions, but more commonly mixed snow/ice/slush conditions. I have encountered two major problems in winter conditions so far.

The first problem is changing tension. I use the Gates iPhone app to check my belt's tension. I have noticed that, if the belt is tensioned properly at about room temperature, then the tension in the belt decreases below the recommended tension range when the ambient temperature drops below about 20℉. I have noticed problems with the belt drive when tension is too high or too low, including excessive noise, skipping, and misalignment leading to dropping the belt from the sprockets. Therefore, I found it necessary to retension the belt slightly in the beginning of the winter and again at the end of winter. I'm not certain yet if the weather-related change in tension is caused by frame shrinkage (I suspect this is the case - my frame is aluminium) or by another factor.

The second problem is getting snow in the drivetrain. Under certain winter weather conditions, the belt will drop from the sprockets. I've had this happen on several occasions, and it's quite annoying, as there's not much you can do when you're on the road besides remount the belt and pray it doesn't happen again on your ride (spoiler alert: if the belt drops once, the belt will get dropped again). However, this does seem to require the perfect storm of conditions: you need the belt tension to be low (possibly because the temperature is low - see above), and you need very heavy, wet snow that sticks to the components of the drivetrain. When the snow and cruft starts building up on the sprockets and belt, the liklihood of dropping the belt increases dramatically. The solution to this problem seems to be to increase the tension of the belt, though I found it necessary to take care not to increase the tension too dramatically, as an overtensioned belt can be very noisy and create a lot of resistance in the drivetrain.

Overall, with winter weather in the mix, I've found that the belt is not the universal, maintenance-free drivetrain that Gates claims it to be, though with a little care, it does require less frequent attention than a chain-based drivetrain.

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I doubt its the frame expansion/contraction (by my rough estimates, this would be on the order of a hundredth of an inch over the relevant portion of the bike) -- more likely belt. –  Batman 8 hours ago
    
@Batman: a hundredth of an inch sounds roughly correct, but that should be enough to change the tension of the belt. When I adjust the tension myself, the amount that the sliding dropouts move to change the tension by a similar amount is about that much (I'm talking about a quarter to half turn of a 30-pitch screw - I believe that's on the same order of magnitude as 1/100th of an inch). I'm sure somebody who knows more about physics/material science/engineering than me could crunch some numbers for a more precise and accurate estimate of the effect of contraction on tension. –  jayhendren 4 hours ago

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