Worn teeth on front mech?

[Halfmanhalfbike]

Just recently my chain has started slipping when I reapply tension after freewheeling. It "snaps" and is then OK.

I've checked the chain hasn't stretched with the chain wear tool....no problem there

The slipping is definately coming from the front chainset, not the rear cassette

Time to replace the front set?

 

[Gerry Attrick]

This is an unusual situation. Have you changed several rear cassettes? Front chainsets generally don't skip when worn, they tend to hang on to the chain, not releasing the return run smoothly. It's known as "chain suck".

Could you post a good quality large photograph of the chainset sideways on?

 

[Halfmanhalfbike]

This is an unusual situation. Have you changed several rear cassettes? Front chainsets generally don't skip when worn, they tend to hang on to the chain, not releasing the return run smoothly. It's known as "chain suck".

Could you post a good quality large photograph of the chainset sideways on?

I would if I had a digital camera

Thanks anyway. It's not too bad but if it gets worse I'll take it back to LBS

 

[e-rider]

you need to improve your use of terminology - the front mech is the thing that changes gear between chainrings

unless you've cycled with a rusty or seriously worn out chain, or you've done 10,000+ miles it's unlikely that the chainrings are worn. And even if they were, they wouldn't cause the chain to slip as you describe.

The problem lies elsewhere

 

[g00se]

No experience if it's this - but something to check with the bike off the ground...

Could there be a tension/sticking issue with the rear derailleur cage/freewheel? When you're freewheeling, maybe the chain is 'sagging' at the top rather than keeping taught? So when you then take up, there's a lot of play in the chain that can miss-catch on the front cogs?

 

[Halfmanhalfbike]

No experience if it's this - but something to check with the bike off the ground...

Could there be a tension/sticking issue with the rear derailleur cage/freewheel? When you're freewheeling, maybe the chain is 'sagging' at the top rather than keeping taught? So when you then take up, there's a lot of play in the chain that can miss-catch on the front cogs?

Yep. That's exactly it. Thanks

 

[gwhite]

Yep. That's exactly it. Thanks

If that is the case then lubricate the large pivot on the RD which controls the tension spring. This can become very sticky which means the chain is not kept in tension.