rear gears problem

steviecapt

I have a specialized hardrock comp bike, when i change the rear gears they work great but when i stop at a junction and reverse the cranks to get ready to pedal the chain works its way down two or three cogs on the rear cassette, this also happens when i push the bike backwards to manouver the bike, has anyone got any ideas why this is happening cheers steve

diy

Does this only happen when in the big ring at the front or all gears?

If so try to avoid extremes of each other. e.g. gear 8 or 9 at the back on the granny or gear 1 or 2 on the big ring.

Also check that your front mech is not too tail out:
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steviecapt

thanx for your reply, the problem only occurs when im on the largest cog up front and when im in 5th or 6th gear at the back btw my bike has 24 gears also checked front mech all is ok

cooldad

Maybe the back end needs a clean and a chain lube. Can happen if jockey wheels etc are gummed up.

steviecapt

the bike is only two weeks old, already tried chain lube, the gears work fine indexing up or down the cassette, i've tried to adjusting both derailers but can't seem to get rid of this problem, any other ideas welcome cheers steve, rather sort it myself than return it to the shop where i bought it from

supersonic

Sounds like a fine tuning issue to be honest.

tri-sexual

if the bike is only two weeks old then i would give it back to them and let them give it a good check over / service.

i agree with SS that it can probably be fixed by fine tuning the rear mech and sorting out the indexing.

if i understand your problem correctly the chain is rough when you pedal backwards and its seems to be in the wrong gear so jumps to a different cog?
try turning the cranks backwards (with your hands - in your workshop/at home) in the problem gear ratio you described when the bike is stationary, if the bike feels rough when you do this and the chains skips over several cogs, try changing gears on the rear mech-if the problem goes away in a different gear then some fine tuning can get rid of the problem. the park tool web site is a pretty good source of information, you tube also ha some good videos which may be of help

bails87

When you pedal backwards the chain doesn't pass through the rear mech before hitting the cassette. So the only thing determining which cog the chain sits on is which chainring it's on at the front.

When you're on the big chainring, the chain will naturally wander towards the smaller cogs on the cassette.

nicklouse

more so with a new chain.

the system is not designed to work backwards.

But as the chain wears it will flex more easily and is less likely to change when back pedaled.

steviecapt

thanx for all the replies took it back to the shop it was due for a first service anyway they said the same thing as the chain eases up it would usually cure the problem, only happens on the big cog up front anyway, middle ring no probs at all cheers steve