invisiblehand

Howdy folks,

I check the belt annually and never noticed any cracking or similar. But as you can see in the photos, the teeth on the belt sheared off this morning. It was a close call but managed to avoid a crash and the motor vehicles around me. I'm obviously going to replace the belt but my question is about maintenance.

Is this a freak incident or is this something that should be checking more frequently? The bike and belt are a little more than five years old. Generally it's kept in the garage at home but at work it sometimes gets exposed to the elements. I don't keep tabs on mileage, but it's my multimodal folding bike so while it gets a lot of use, the mileage is low.

Thanks for your help and advice.

EDIT: I'm also wondering whether there were other things to double check. For instance, is teeth sheering a consequence of belt tension being too low or high?

pdlamb

How many miles (and months) did you have on that belt?

What's the recommended maintenance replacement interval?

Andrew R Stewart 

My friend recently replaced his Gates belt and ring on his CoMotion. The old had MAJOR wear after 4 or 5 years. He was beginning to have some slip under pedal pressure. When i looked at the old parts I thought "duh, of course you'd have skipping" as they were pretty trashed.

One concern i have had with belts is how they are marketed and who uses them. The claims of "maintenance free, long lasting..." tend to appeal to those who don't want to do the maintenance on their bikes. Some of these bikes see a lot of exposure and hard hours. A mix of high expectations and wanting to do less work often can be disappointing when the inevitable happens.

My suggestion is to learn that your next bely might only be good for about 4 years of safe and reliable use. I would consider replacing the cog and ring if there's any wear showing at all. Belt tension should be checked more often than annually. Make sure that the alignment of the cog and ring are spot on. belts don't tolerate meshing on off plane cogs or rings well (far less than chains do). Of course all the other standard parts that make up a gear system need to be kept up. With the high tension of the belt some hub and bottom bracket bearings can wear quicker than with a chain.

Lastly if you want this bike to be good for many more years I strongly suggest you get a bunch of spares, before they become obsolete and unavailable. Andy

veganbikes

If that belt is a Gates Carbon Belt then reach out to Gates, they are super nice and helpful.

Like Andrew R Stewart said check belt tension more often and alignment especially. Spares are handy to have on hand though I don't think Gates is going anywhere, they have been around since 1911 and seem to be quite committed to bikes. However it never hurts to have an extra belt. I learned that lesson after getting into a crash but they replaced the belt under warranty (even though it was not) and I bought a second one just in case and might end up getting one more to keep around.

invisiblehand

They don't really give a replacement interval. STRIDA only has some blip on the mileage that kevlar belts last on cars. Memory says that some of the foreign STRIDA websites say something on the order of 10s of thousands of kilometers. (50000 km?)

I use the bike as a multimodal commuter. So every commuting day is roughly 3 miles of riding plus some occasional errands downtown; e.g., see my dentist. But I don't go into the office every day and certainly not during the height of the pandemic. Upper end of an estimate would be 4-5 thousand miles over the last 5 years.

https://www.strida.com/faq/

Yeah. I've had a conversation with some STRIDA users and the best theory is that a little too much play in the belt developed such that when I started to pedal, the teeth gave way. So yes ... check the tension more regularly and make small adjustments to keep it within the appropriate tolerance.

Some additional context. This happened after stopping at a light. So there was probably a lot of torque on the drive afterward.

base2 

My understanding is that when the belt is under tensioned it loads the nubs differently & they become like gear teeth & inevitably rip off as it is only the nub tip that is being loaded. Proper tension loads the entire belt structure from the base of the "v" between the nubs & the nubs themselves become something of an anti slip feature.

I've also been told that when properly tensioned, most bikes/belts are about in tune with the "D" string of a guitar.

The rub is when selling bikes most consumers notice the slight running resistance of a properly tensioned belt drive & being Leary of "not chain" already, they will not purchase the bike unless the belt is loose like a chain. (About 1/4 inch play up/down.) So bike shop mechanics set them under tensioned on purpose because that is what the consumer expects. The consumer who does not know any better, suffers short product life & less than satisfactory performance.

I may be wrong & I welcome any correction.

invisiblehand

That's intuitive.