Chain problem

alex100a

Following recent advice received on this forum regarding the correct bottom bracket for my old Gary Fisher MTB, which I've been doing up, I today fitted the new part (113mm!) and now, after several attempts, have all 24 (3x8) gears working almost perfectly.

The problem I have is that when I have the chain on the biggest sprocket and chainring it does not sit well on the chainring when pedalling. Its as if it wants to jump down the middle chainring. This eases as you change to smaller sprockets but is annoying as it feels awful when pedalling. It does not happen in the middle or small chainring.

The drive set is all new Shimano entry level gear (HG51 cassette, HG71 chain, FC-M410 crankset).

Does anyone think I could have done anything wrong? or is this just a result of the parts I've put together and that I simply need to avoid these gear combinations of gears? or could this settle down with a bit of use?

supersonic

It's a case of avoiding those gears - it slews the chain at an extreme angle and can cause the problems you are experiencing. There is no real need to use them, as the gear is replicated in the middle chainring - ie 42/32 gear is roughly the same as the 32/24 - and the latter has a much straighter chain.

The Rookie

WELCOME BACK SS!

As above, on a 3x8 you should never use large/large or small/small, and ideally not the sprocket next to it either if you can avoid it.