Bike chain changes gear when pedalling backwards

DarkEnergy · April 26, 2018

It might just be by design, not sure. Today I finally decided to figure out how to fix my bike and adjust the brakes and gear shifting so the chain doesn't rub against the front derailleur. I've fixed everything and the only issue left is that when the chain is on the biggest two chainrings (front) and largest gear on the cassette (rear), if I pedal backwards the chain will move from the eighth to the seventh gear on the rear cassette. This is because of the angle the chain is at. The thing is, the chain isn't really touching the front derailleur so that's not the problem. It's literally just that the biggest two chainrings in the front stick out too far on the bike compared to the biggest gear in the cassette which is close to the bike.

Before I start pedalling backwards. You can see the angle of the chain pulling away from the cassette (which isn't a problem when pedalling forwards):

As I start to pedal backwards the chain moves off of the 8th gear:

dfsdfgfkjsefoiqzemnd · April 26, 2018

This is indeed due to the angle your chain is at. Keep in mind that riding on large-large and small-small will wear out the chain and the sprockets a lot faster.

Put it in the middle gear at the front and the 4th or 5th at the rear. The chain should be almost perfectly straight. Now Pedal backwards. If it doesn't run smooth, your rear derailleur needs to be either adjusted or realigned.

DarkEnergy · April 26, 2018

2 minutes ago, Captain Chaos said:

This is indeed due to the angle your chain is at. Keep in mind that riding on large-large and small-small will wear out the chain and the sprockets a lot faster.

Put it in the middle gear at the front and the 4th or 5th at the rear. The chain should be almost perfectly straight. Now Pedal backwards. If it doesn't run smooth, your rear derailleur needs to be either adjusted or realigned.

Yeah, it's pretty much straight and smooth.