Slipping chain.

[Baby Huey]

Can anyone advise me what might be causing this.

I bought a secondhand GT hybrid bike the other day, it rides fine apart from when going up hill and exerting yourself when the chain seems to slip.

I've had a look at the chain, gears etc and can't see anything untoward.

[jodypress]

Chain could have stretched. Any bike shop will have a tool to measure the chain.

[alphadog]

After trying a new chain, it turned out the sprockets were worn out on my old cast iron leviathan (an ancient Saracen full sus) though this was quite hard to tell visually - got the whole lot replaced and a new bottom bracket for the princely sum of £65 by the local bicycle place.

[littleandy0410]

Could be the front chainset, but more likely is the chain and cassette which are worn. As someone else said, get hold of a chain wear indicator tool: http://www.chainreactioncycles.com/Models.aspx?Par...

If the chain is worn, you'll need to replace the cassette too.

[rhinochopig]

littleandy0410 said:

Could be the front chainset, but more likely is the chain and cassette which are worn. As someone else said, get hold of a chain wear indicator tool: http://www.chainreactioncycles.com/Models.aspx?Par...

If the chain is worn, you'll need to replace the cassette too.

and possibly rings.

[pdV6]

As has been noted, it's time for a new chain & cassette and (if you're unlucky) chainrings too.