How do I realign my gears?

[Boris Bike]

Hi all,

Had a back tyre puncture and since changing it and putting the wheel back on, the gears are slightly out of whack. Sometimes they slip, and in some gears you can hear the chain trying to change.

I turned the bike over and tightened/loosened the cable, moving up and down the gears until I thought it sounded right but it's still not perfect.

Is there a particular method to doing this? SRAM Apex if that makes a difference.

Cheers

 

[Rob3rt]

1st thing's 1st, the only thing you changed (that you realised) was taking the wheel out and put it back in, so double check the wheel is properly aligned in the dropouts.

If this doesnt resolve the issue then maybe you accidently altered the cable tensioner on the mech, drop your gears down to the smallest cog, then release the tension using the adjuster on the rear mech. Now shift up on the shifter while turning the pedals, it will not shift because the tension is insufficient, now start to increase the tension on the mech adjuster while continuing to turn the pedals, it will start trying to climb to the next cog, keep turning the cable adjuster until it jumps up, go a bit further until any chattering is minimised. You should now be good to go, but go up and down through the cassette a few times, if it struggles to climb a gear, up tension just that tiny bit more. Once it is going up and down fine, go test ride it.

PS, you may want to turn the bike upside down if you dont have a workstand. Or you can lock the bike in a turbo trainer but don't engage the resistance unit (unless you want tired arms and enjoy making things hard for yourself).

 

[Boris Bike]

Good point. I'll check that when I'm leaving work.

But I have been fiddling with the gear cable, so I'll probably need to align it again anyway.

 

[Rob3rt]

Read my above edit, described the indexing process.

Also, you can try cleaning and lubing the cable, shift into the largest cog at the back, then stop turning the pedals and keep shifting the shifter back down to the smallest cog (but dont turn the pedals, you want the chain to remain on the largest cog, but the shifter to be on the small cog end of it's range). This will give enough cable slack to dislodge the inner from the frame, you can then slide it up and down the cable to get at the cable to clean and lube. Once done, put the inner back in place and shift the shifter all the way back the other way to bring back the cable tension.

 

[Boris Bike]

That's great - thanks so much Will try it out later.

 

[Rob3rt]

No problem, had a similar issue myself just yesterday (mech seemed to be unable to decide which gear to stick with in the middle of the cassette and so was jumping up and down randomly and the chain was skipping) and a friend helped me sort it using the above process (so he gets credit for the above, not me, just passing it on)

 

[accountantpete]

I turned the bike over and tightened/loosened the cable, moving up and down the gears until I thought it sounded right but it's still not perfect.

Cheers

That is a good way of doing it - but why not also look at what is going on at the same time and get things spot on?

The top jockey wheel should be aligned perfectly with the sprocket. If not it throws the chain to one side which initially causes the chain to brush the sprocket next to it causing the noise. If it is a bit further away from the centre the filed teeth of the sprockets will start to let go/grab and the chain will start to want to change sprockets.

So all you need do is centre the jockey wheel using the adjuster and sight and then fine tune if necessary.

 

[Boris Bike]

Purring like a kitten again Thanks all.