Helping my kid with a dirt jump frankenbike project. Finally put the chain ok but when he pushes hard on the pedals the chain seems to skip a few teeth on the rear gear. It's a single-speed chain with a 24T chainring and a 14T gear in the back + a chain tensioner. Old MTB frame has vertical dropouts. Have shortened the chain as much as possible. Any advice or hacks are highly welcome!
by elpeebee
8 Comments
Also, kid weighs 82kg and can put out a lot of power….
Looks like a worn chain and/or sprocket problem.
Not a worn chain problem as the other comment suggests. The issue is that your chain tensioner isn’t intended to be perpendicular with the chain stay as it appears to be in the video. Take a link or two more out of the chain. This will bring the tensioner closer to parallel with the chain stay. The issue will resolve
Chain and sprocket could definitely be worn, but my money would be on the chain line.
Try to make sure the chain line is as straight as possible. I’ve had issues with the chain slipping under load on my SS builds when it’s just a tiny bit off.
This could be done with a combo of BB spacers, FH spacers (if using an HG freehub or something similar, and tensioner alignment adjustment.
Not saying this is definitely the case, but thats where I’ve had issues before.
~A big wide single speed chain can help with this too, gives it some extra width to move around.~
Edit: missed this in your post! My bad. 🙂
Good luck!
Is the chain new? If not, get a new one. If it is make sure you sized it correctly following [this guide](https://www.parktool.com/en-int/blog/repair-help/chain-replacement-single-speed-bikes). If it’s still skipping, the sprockets need to be changed. Check the chainring in the front for signs of wear, in the rear it’s harder to see. You probably need to replace both.
Single speed can take either an 1/8 inch or 3/32. 1/8 inch being most common, you might want to check the width of your chainring and sprocket. If you happen to have a 3/32 chain on a 1/8 inch sprocket it won’t work very well.
It could also be that the chain line from the sprocket to the chainring isn’t in line with one another.
Single speed can take either an 1/8 inch or 3/32. 1/8 inch being most common, you might want to check the width of your chainring and sprocket. If you happen to have a 3/32 chain on a 1/8 inch sprocket it won’t work very well.
It could also be that the chain line from the sprocket to the chainring isn’t in line with one another.
Looks like very little wrap around the cog with that tensioner. I’d think a longer chain would help that. Or the chain/sprocket are worn. Was it all new parts?