slipping gears

secretsam

Hmmm, now someone's going to say "get on the road advice thingy" about this, but anyway...

The Sirrus has developed a nasty habit of slipping gears, keeps popping between them and jumping up and down without me changing, especially when I put a stomp on (eg uphill)

What's going on? Haven't whacked the mech or anything, don't think it's all worn...

It's a Shimano Sora at the back. Am not familiar with index gears, bike 2 still has the old fashioned "It's in there somewhere" system :roll: ...is it adjustment, perhaps?????

Please help, it's driving me nuts and can't be doing the bike any good...

el_presidente

scrap it and get a singlespeed




otherwise, sounds like the cable has stretched so the indexing isn't dialled in. there'll be a thing somewhere called a barrel adjuster, twiddle that a bit til it's dialled back in again

google it on Sheldon's site & I'm sure he'll give you chapter & verse

EDIT try this from Park tools

http://www.parktool.com/repair/readhowto.asp?id=64

hamboman

cables have stretched?

Pat920

Have you taken the rear wheel off recently? If you have, undo the quick release, give the wheel a shake and do it up again (this has caught me out before).

Otherwise, set the gear change to the middle gear and spin the pedals. Eye in the shifter mechanism - is it lining up with the middle cog or is it slightly off? Adjust the shifter with the barrel adjuster at the end of the cable until it aligns. With mine, the direction you turn the top of the adjuster is the direction the shifter moves.

Gussio

hamboman wrote:

cables have stretched?

This can happen with a new cable. Quarter to half turn of the barrel adjuster sould rectify.

The OP might want to check that the chain isn't worn?

el_presidente

Another way to use the barrel adjuster; stick the chain on the smallest cog. Twiddle the adjuster until the chain is rattling on the next cog. Then back it off by a quarter turn each time until the rattling ceases. Voila your indexing is dialled in.

secretsam

Thanks everyone

Sounds like you've nailed it, needs adjustment, bingo-have also taken rear wheel off recently so that may be a factor

Gambatte

easy way to check if cables stretched.
ride the bike and change down to the small cog at the back.
If you dont have cable outers running full length, check the inner cable as it runs exposed down the front of the frame or along the top tube. This shouldn't have any slack. If it has, it needs adjusting to take it up with the already mentioned barrel adjuster.

secretsam

Thanks all, think I identified the problem - when I put my front light in, it was catching on the gear adjuster next to the lever

Had a bit of a twiddle which seemed to fix it but think I've overdone it...bike now running on 4th gear when indicator says 3rd, and changes are slow and erratic

Oh bu99er I think I've f :evil: cked it, trip to the LBS workshop no doubt...

cupofteacp

I think you might find that the chain is worn, if it jumps when you "stomp" it

secretsam

cupofteacp wrote:

I think you might find that the chain is worn, if it jumps when you "stomp" it

Nope, that's not a problem, it's a recent thing since I've been using lights a lot :roll: so think I've knackered the adjustment, and am not up-to-speed on indexing so am not confident enough to DIY. Bike 2 has old fashioned hunt-the-gear shifters which I'm more than happy sorting out myself!!!!