Rear Mech Jockey Wheels

kevinharley

Hi,

Was out on my Giant Terrago at the weekend - was all very muddy - and after a bit, noticed that in certain gears, the pedal stroke would just stop. Figured it was too much mud in the rear mech, clogging up the chain, and causing it to just lock in certain position / gears.

Got home, gave the bike a good shower, went to re-lube all the appropriate bits, and noticed loads of play in the lower jockey wheel in the rear mech, but also the chain 'jumping' on the lower wheel every half pedal stroke or so.

The rear mech is Shimano Deore. Its just over a year old, and has had a good (but not excessive) amount of use in that time.

Figured the problem maybe one of two options... either:

a.) the jockey wheel(s) and/or rear mech has worn out and needs replacing
b.) the chain has stretched so that every half pedal stroke, the length of the chain is too great to sit comfortably on the jockey wheel teeth, thereby pushing the jockey wheel to one side and occasionally causing the chain to jam in the cage.

Any thoughts or suggestions?? :?:

Cheers

stumpyjon

Jockey wheels do have some play in them. At a guess I'd say it is more likely to be a combination of stretched chain and worn chain rings. If the chain rings wear the chain doesn't always release (chain suck) and sticks to the chain ring effectively going underneath itself. It may feel like it is the rear mech that is causing the problem but it's probably not. This problem is made worse by mud.

You can get replacement jockey wheels if you want, the whole mech should not need replacing unless you've bent it.

Best start off by checking the chain for stretch (get a Park Tools chain checker, very easy to use and only about £ 8 ). If the chains stretched a lot (more than 1%) you may be looking at new new chain, chain rings and rear cassette.

supersonic

Top jockey wheels float; bottom ones should not. Needs replacing.

But as Jon says, other parts could be worn after this time.