Aligning rear wheel (geared)

i seem to have a problem getting my rear wheel centered correctly, so that the mech interfaces properly with the cassette.

the frame has vertical dropouts, my rim is a bit out of true.

i can make it happen and work nicely, but to be honest its just seems to be luck and a lot of fiddling. i usually hold the wheel from the top and use the weight of the bike to make it find its place, but this doesn't normally work all that well.

what is the technique to getting this right without all the faff?

Have you checked you derailleur hanger isn't bent?

A photo would help me/us diagnose.

Surely the derailleur is mal-aligned, not the wheel??

no its defiantly not bent. there is play in the dropouts and once its in the right place it works perfectly.

i could adjust the derailleur to fit the wheel, but wouldn't i then just setting to a wheel that isn't aligned correctly? thats not really solving the problem.

i would show you a picture but there isn't really anything to see. nothing is damaged and the only way you can tell its wrong is the noise and the slow/jumpy gear changes.

Rear wheel correct spacing?

no its defiantly not bent. there is play in the dropouts and once its in the right place it works perfectly.

i could adjust the derailleur to fit the wheel, but wouldn't i then just setting to a wheel that isn't aligned correctly? thats not really solving the problem.

i would show you a picture but there isn't really anything to see. nothing is damaged and the only way you can tell its wrong is the noise and the slow/jumpy gear changes.

Sounds like the derailleur needs tuning, im no mechanic though! You know how to do it? It's not hard, park tool have a good online database of mechanical skills.

the bike is an off the peg fuji, the wheel is the right spacing.

http://www.sheldonbrown.com/derailer-adjustment.html