Gears changing 2 in one go

[jimbob]

I'm having problems setting my rear derailleur up. There's always a position on the cassette where it jumps 2 gears at a time. It shifts fine for the rest of the range. Its a 10sp shimano if that helps.

Anyone have any ideas? Thanks!

 

[Zimmerframe]

Assuming you've re-indexed it and it's perfect through all the other gears, then it could be a bent hanger or knackered jockey wheels ?

 

[Andrie]

I had this happened to me on gear 6 only. No matter how good I indexed it and changed the hanger. After closer inspection I had a bent cog! My 6th gear sprocket has a bent and I don’t know how that happened. Replaced the cassette and all is good

 

[jimbob]

Thanks. It happens either in the 3rd or 9th cog depending on how I adjust the indexing. Ths others shift fine. If I adjust it so it doesnt skip on one of the cogs, the other then jumps.

Its almost like the shifter is pulling too much cable for each gear. Has me stumped.

I've not had the bike for long and not sure if its always done it or a new develolment.

 

[alan_sh]

Is it the right gear changer for the number of cogs?

 

[steve_sordy]

Check that the mech is bolted to the hanger securely, the the hanger is bolted to the frame. That the axle bolt is properly torqued. Over the years, all of those things have caused your problem for me.