wheelhot

Hi,

As per title, anyone has any idea why this happens and how to fix it? I'm not sure if it's the FD or RD or cable tension causing this problem.

Previously, before I sent the bike to the mechanic, I am able to rotate the crank backwards and the outer chain will not drop, but today, it drop into the inner chainring (and obviously missed it).

Any suggestions?

Thanks

Trakhak

Any derailleur-equipped bike with undamaged drive train components can tolerate being pedaled backwards when the chain is in a more or less straight line from somewhere near the middle of the cassette to the chainring. (That's probably where the chain was when you were able to backpedal without derailing the chain.)

Some bikes with long chainstays can tolerate being pedaled backwards with more extreme offsets between the cassette sprocket and the chainring.

Bikes with short chainstays often can't be pedaled backwards with extreme chain offsets without derailing the chain.

Think about it: the whole drivetrain is optimized for derailing the chain when you want it to derail, which means that it's also optimized for derailing at other times, such as when you're pedaling backwards.

The old joke: "Doctor, it hurts when I do this." "Then stop doing it."

wheelhot

That's interesting cause I didn't have this problem before the mechanic maintained the bike, but from the sound of it, this behaviour is okay and perfectly normal?

Trakhak

I wouldn't call it a problem, because, yes, it's okay and perfectly normal.

If the derailleurs are adjusted such that the bike shifts through the gears correctly when you pedal normally and no parts were replaced by the mechanic, chances are that what you remember as problem-free backpedaling was, as I explained in my previous post, contingent on your backpedaling with the chain in a more or less straight line from the cassette sprocket to the chainring.

GrainBrain

Clean and lube your chain

HillRider

The only time it can matter is if you have to backpedal a fraction of a turn to position the crank from a standstill such as at a traffic light.

2manybikes

It's not a problem. If it's OK when pedaling forward, don't worry about it. The chain tensioning does not work right
, and there is no derailleur guiding the chain onto a ring either, when pedaling backwards.

zacster

It happens on my bike when I'm in the big/big combination. Not only does it happen when I backpedal, it frequently happens when I'm off the pedals too because the derailleur tension is so high that it pulls the chain backwards. My solution? Don't leave it in the big/big combination. I have it tuned so it otherwise shifts fast, silently and flawlessly.

fietsbob

Old Gummy, cold, grease in the cassette driver? chain go slack?










..

fietsbob

By the way there are chain keepers that block the chain from coming off inside of the innermost chainrings..