Why has my chain started jumping\slipping?

[Hacienda71]

Any one got any idea why my chain has sarted slipping and jumping while on the smallest rear cog? It seems to be worst while on the middle front ring. The cassette and chain look fine and have only done about 1200 miles. The issue only seems to be on the smallest cog. When putting power down today the chain was slipping like a worn cassette and when back pedaling the chain seems to jump. The chain is pretty clean and is regularly lubed.

Cheers

 

[yashicamat]

I'm no expert, but with the chain on the smallest sprocket, the spring tension will be needed the most in the rear mech to keep the chain taught - is there enough tension? Maybe the chain was a touch long to start off with and as it's worn slightly it's just tipped over the edge and started slipping?

Edit: try it with the chain on the big chainring (I assume you've got a triple from the 'middle chainring' remark) and see if it does the same thing. If it is a spring tension issue, then with the extra slack taken up on the big ring it shouldn't jump.

 

[naffa]

Is your chain clean and well lubed?
I ask this because recently my chain started doing the same and I abandoned a ride due to it heading instead to my LBS.
He found a dry chain link that was kinking. Cleaned the chain and lubed it for me and ts been fine since.
Well the chain has, gonna start another thread about another issue thats just shown itself.

Nath