RideCO

I seem to have trouble shifting, first thing I noticed was it was reluctant to get off the smallest gear on the cassette, its slowly gotten worse, now I have trouble shifting both ways, mostly on the right side (small gears) which also means I'm usually on the big chain wheel (it seems gets worse towards the smallest gear). It just doesn't always shift when I move the lever, but by shifting 2 gears and back 1 always puts the chain where I want it, and there is never any noise when its in the gear its supposed to be in.

I cant figure out an adjustment that should help. I'm not very good with rear derailleurs. Can this be caused by a bent derailleur? It doesn't look bent, and I haven't crashed.

Mondoman

Perhaps your RD cable/housing needs to be replaced?

taliesin

+1

What kind of RD are you using? What shifters, cassette, etc? How old is the bike?

DannoXYZ 

Sounds like too much cable friction. You should adjust cable-tension (increase) so that it goes from small-to-big cogs OK. This is done by force at the lever. However, shifting from large-to-small cogs is done by the return-spring in the rear-derailleur only. So if you have too much cable-friction, the RD won't move or move slowly when you release a click at the lever.

rogerstg

Without disagreeing with previous posts, I'd tighten the cable tension about a half turn of the barrel adjusters at a time. I like to try the simple stuff first.