Hi

I know little about bike mechanics and my (large very well known)bike mechanics are very poor.

The bike has just had new chain, crank and rings to cure chain suck and very recently had a rear cassette.

On the first ride since the new crank was fitted I am getting another problem:-

Under load in any front cog the chain seems to ‘jump’- It’s almost as if the chain is slipping on the cogs (but more likely trying to go up/down a cog although it doesn’t actually go up or down)

Am I correct to assume this is a rear deraileur issue?

THx

Andy

Nope, its the new chain on the old cassette… The recent new cassette was not recent enough. Try your old chain on it see if I am right.

Check that the cassette isn’t loose and that the new chain is the correct size.

Or could be freehub body that failing.
But I’d try the above first

OK will try that. New chain should be correct size – but wouldn’t put it past my crappy bike engineers to put wrong one on. I will c if the cassette feels secure.

Freehub should be ok – both wheels new within 30 – 40 rides (hope pro hubs I think)

The only reason I suspected the rear deraileur is cos it looks to bend in towards the bike very slightly (allthough the bracket holding it doesn’t seem bent) and has a tiny bit of play in it.

Almost certainly the cassette – a new chain on a slightly worn cassette often causes probs.

If it’s the freehub the cracking noise is quite loud and with Shimano hubs it will only do it two or three times before it fails.

If it’s the mech there will be issues with the shifting and lots of k-tikka-k-tikka noises going on as the chain tries to climb off the cogs

As a start I’d re-do the rear mech setup from scratch – poor setup can cause all sorts of wierdness with shifting.

I’d put a fairly significant bet (possibly even up to £1) on it being the cassette.

I had chucked the old chain so took the bike back (for the third time) and they fitted a new cassette.

Went for a ride last night and it is definately improved but still did it a few times – but towards the end of the ride so perhaps it was caused by the mud (allthough it wasn’t a really muddy ride)