Right, ripped my mech off last week(Chorus), new mech hanger and chain(KMC X11L) fitted and I still have issues.
Gears set up perfectly in the stand, nice and smooth and sharp, going where they should be etc.
On the bike it just moves down the cassette as soon as I put anything thats more than a gnats fart on the pedal.
On todays ride I had to use the larger shift lever to hold it in place to stop it.
I'm thinking it may be the cassette is worn? The current one has around 800 miles in on it I'd say since the start of the year.
Anything else to check before I go drop £100+ for a new Cassette?