Midrange shifting issues

tomfoolery

I've just spent an hour or so with the bike on a stand adjusting the rear derailleur handlebar barrel trying to get it to shift up and down smoothly in all gears. I can either get it to shift up smoothly and fairly quickly, or change down - but not both. The problem is in the middle couple of the 8 gears. It just won't pick up to the larger cog or drop off to the smaller ones without over/under shifting and then clicking back. Any ideas what could be causing this? I've oiled the chain and the cage which seems to be moving ok.

fossyant

Check for cable snag - i.e. dirty cables

gs3

I agree with fossyant - usually dirty cables especially in the shifter or in the loop of cable-outer going into the mech (Shimano) If your mech is Shimano type, you'll get better results using the barrel adjuster at the mech. Also blast some TEFLON-type lube into your shifter.

afctumike

Also check that the bottom jockey wheel is perfectly in line with the sprocket that the chain is on and remains in line with the chain at each change. My chain was jumping in mid-range earlier this week and after a visit to a LBS it was fixed. The derailleur must have been knocked at some point..

Drfabulous0

Could be any one or more of the following:
Dodgy cables
Bent hanger
Bent derailleur
Wheel not seated correctly in dropouts
Worn cassette
Worn chain
Worn jockey wheels
Build up of crap around mech/cables
Dodgy shifter
Cable clamped around the wrong side of the cable clamp bolt
Something else entirely

Probably best to take it to the bike shop and ask them to take a look, or just change to single speed instead.