Hi – need some help as I have to get my road bike up to scratch as I have been coerced into a sportive in a few weeks.

Somewhat bizarrely the gears index perfectly from the largest sprocket to about 4 or 5 and then jump about all over the show. I have replaced the chain and ridden for 50 odd miles but no change. Why should half the casette act differently to the the other half? Do I need a new cassette ??

Please, any ideas as it’s driving me mad :-0

Bent hanger?

Sounds like the indexing isnt spot on. Have you got any fraying on the cable at any point thats fowling the action of the rear mech in the higher gears.

Sounds like a worn cassette, but could be a bent mech? Cables in tip top condition?

Go back to the beginning.

Strip out the rear mech cable, check the outers.

For a few bob just replace them.

Whip the chain off and check with a wear gauge.

Set the max/mins on the limiter screws and re assemble.

Trying to overcome without going back to basics does not work in my view (cytech 2 trained wannabee here)

Hi – thanks – cable and hanger fine so will try a new cassette.

How do you know the cable hanger is fine? Have you checked it with a alignment tool? I’ve regularly looked at a gear hanger, thought it eye-balled up ok then put the alignment tool on it and found it was off screwing up the indexing.

Tend to find if it indexes at one end o the block but not the other it’s bent.
If it slips under load then it’s worn out cassette.

But I always try to change the cables first it’s far cheaper

I have checked and whilst there is no mech hanger as such – what it hangs off is fine. Honest 😉

Just a thought – but if it was the cassete at fault – why would it jump around the half that has been least used – doesn’t make sense ??

why would it jump around the half that has been least used – doesn’t make sense ??

If you hardly use that end, my guess is that your mech’s filthy with road-glue and the spring can’t pull it far enough over

plusgas

mmmmmmm, plusgas !