Chain slipping.

[Dave.B]

Out today, 15 miles from home the chain started jumping when on the 14 tooth cog. Nothing visible except the usual crud stuck to the cassette. Full clean-up and inspection once home, found these stuck either side of the cog.

 

[urastus]

Out today, 15 miles from home the chain started jumping when on the 14 tooth cog. Nothing visible except the usual crud stuck to the cassette. Full clean-up and inspection once home, found these stuck either side of the cog. View attachment 85328

Geez, I probably have the same thing - I'll go and look now. Talk about brain dead. I've felt a bit of a slip in the higher gears, gave a casual glance, looked at derailer alignment, and continued on - doh!

 

[Dave.B]

18 years of riding, 4 bikes & numerous rear cassette's/ chains I've never had anything except grass in-between the cogs. It's got to be down to the grit finish on some of the cycle paths & footpaths. The mud and puddles are better surface for bikes.