Hello everyone!
After several years and thousands of miles of commuting by bike, I recently installed a mid-drive e-bike conversion kit on my gravel bike. For the most part, the experience has been absolutely fantastic. However, I'm having some pretty frustrating difficulties with the drive-train, and I've exhausted my expertise.
The bike came with Shimano Claris, which is certainly not the most robust drive-train. When I first installed the kit, the chain was skipping over the cassette pretty much any time the bike went under load. The cassette already had several thousand miles on it, so I replaced the entire drive-train (chain, cassette, and derailleur) with brand new Claris components. This worked great for about 200 miles (~4 days), but then the cassette started skipping again.
I replaced the cassette again and pretty much immediately snapped a chain. I again replaced the chain, and about 50 miles later snapped it again. I brought it to a local bike shop, that once again replaced the drive-train (this time with higher-end components) after noticing one of the cassette rings had been cracked down the middle. I brought it home, only to snap another chain within 50 miles, stranding me several miles from home.
Funnily enough the components are cheap enough that I'm still spending less than I would on gas/car maintenance, but obviously this is something I want resolve regardless.
I'm in the process of looking into more robust drive-train options. My priorities are durability and low maintenance cost/difficulty, but I don't care as much about weight/efficiency. I'm putting several times the power you'd typically put through a drive-train, so I'm not sure most of the go-to higher-end options for typical road cyclists would be sufficient.
I've seen some people discuss more exotic drive-trains like belt drives and internally geared hubs. Those sound intriguing, but also very complex to retrofit. It seems to me like there has to be some sort of drive-train with a larger/thicker cassette and chain, at the expense of having fewer gears. Perhaps something like a belt drive really is the safer option?
I'm willing to spend quite a bit on this, but I want to be confident it would actually be a reliable long term solution.
I appreciate your advice here,
Thanks for the write up! I sort of figured an IGH/belt-drive would involve this sort of complexity. It's an aluminum frame with quick release axles, which complicates things even further. At that rate, it seems to me like a new bike would be the better option.
A local bike shop took a look at the bike, and was surprised to hear about the problem. They said they've never seen anything quite like it, even considering the motor. Their best guess was that the chain-line isn't great, and that could be causing the chain snapping issue in lower gears. The cassette wear can probably be chalked up to it being a $20 cassette.
I think right now, my plan is to try a larger offset on the chain-ring to improve the chain-line. If that doesn't improve things, I'm looking into maybe installing a 5-speed cassette with a thicker chain. This option looks promising, but I'm not 100% sure it will work with my bike: https://www.cycmotor.com/product-page/heavy-duty-drivetrain