Bicycle Mechanics - Chain jumps on one sprocket

Hello All

Hope you can help. I've just replaced chain wheels, chain, jockey wheels on rear mech and 9 spd cassette, all veloce on my Bianchi. Everything is great except the chain constantly jumps whenever I use the 4th sprocket (19 tooth) on both the inner and outer rings. All other combinations are ok. Any advice welcomed!!

I've looked on the forum but haven't found an answer to this prob.

Rgds

Fred Lowry

I know it's a new cassette but my first thought would be that that particular cog is a duff one.

You need to suport the wheel(A repair stand is the best way) and run the drive train in this gear while watching the cass. to see what is going on. If it willnot do it while freepedaling, you can drag the brake(easy way) or hold your hand against the wheel(macho way)

Hello

Thanks for your offerings. I have now sorted the problem, simply by removing the cassette and refitting the sprockets on to the hub spindle. I am unclear how this has fixed the fault as the cassette looked ok on the hub and as it is keyed you can only fit the sprockets one way. However.........

Thanks anyway.

Hello

Thanks for your offerings. I have now sorted the problem, simply by removing the cassette and refitting the sprockets on to the hub spindle. I am unclear how this has fixed the fault as the cassette looked ok on the hub and as it is keyed you can only fit the sprockets one way. However.........

Thanks anyway.

I reckon I know what it was. To remove the cassette you had to take the wheel off, this time when you put the wheel on you seated it correctly in the drop outs. Previously I think the wheel wasn't perfectly in the drop outs and was misaligned in a way that on that cog the chain would catch the ramp slightly and lift just enough to skip.

Could be, if so, I suppose it will show up again some time in the future.

Chrs

Fred Lowry