Jeremy Watts wrote:
I've got a 'Carrera Kraken' mountain bike and i keep getting this
problem where the chain seems to 'slip' around the chain set when in
certain gear combinations.
As I say when in 1 or 3 on the front gears it doesnt do it, but put
it in 2 on the front and apply any pressure to the pedals and the
chain seems to slip right round the teeth on the gear wheel and so
not provide any drive to the wheels.
Someone has said that this is due to worn gear teeth, but i dont
fully buy that because they dont seem worn to me, and its been doing
it a while and was doing it occasionally when the bike was new.
Any idea why this happens?
There are really a couple of potential problems, but your symptoms point
primarily to worn components. Whoever told you it might be the chainring
was giving good advice. What they also failed to tell you was that in
addition to needing a new middle ring, you may also need a new chain and
cassette since they are likely all worn to match the wear/elongation of the
chain. . Drivetrains, while pretty durable in general, need to be viewed as
consumable items. However if you change out your chain before it gets too
bad, you can really extend the life of the rings and the cassette. The only
other thing that comes to mind is a possible bent tooth on the ring itself.
The fact that it happened when the bike lends some weight to that
possibility. Really impossible to tell without actually seeing the rings
and checking the chain.
How long have you been riding with this particular drive train? Do you keep
it clean and lubed? If you're unclear what the problem is or don't
understand what might be causing the problem, your best bet is to bring in
to your local LBS and let them have a look.