[notwist]

I replaced the cassette on my powertap wheel (from 12-28 to 12-27) however now the chain won't stay in the big cog in the back. When i press the shift lever, the derailleur moves the chain to the largest cog but then the chain moves back to the second largest cog when i release the shift lever. I don't think it's a cassette issue as I occasional switch between training and race wheels. not sure why this is happening now. I tried adjusting/increasing tension on the cable using the barrel adjuster however it still doesn't work. I also tried increasing cable tension by undoing the cable bolt on the derailleur and pulling the cable tighter however that doesn't seem to fix it either. any thoughts what could be the issue?

 

[tihsepa]

Missing a spacer behind the cassette?

Either that or a limit screw issue. Limit screws dont go out of wack with a cassette change though. Sometimes if its a different wheel but not a different cassette onthe same wheel.

 

[Kerry Irons]

Missing a spacer behind the cassette?

Either that or a limit screw issue. Limit screws dont go out of wack with a cassette change though. Sometimes if its a different wheel but not a different cassette onthe same wheel.

Assuming all the other shifting is still good, then a missing cassette spacer doesn't seem like the cause. Probably just a tweak of the limit screw will fix it.

 

[notwist]

thanks guys for the input. no spacers missing and i tried messing (nearly unscrewed the low limit all the way) but it still won't stay in gear. no biggie. methinks ill take it to my LBS this week.

 

[cxwrench]

this makes no sense. if it shifted w/ the 11-28 it should shift w/ the 12-27. anything more than a very minor adjustment to the limit screws would be out of the ordinary. why don't you start from the beginning and make sure everything is correct. undo the cable, make sure the shifter is in high gear position. check the limits. turn the barrel adjuster all the way in. verify the hanger is straight. attach the cable, get the tension right and there you go.