I was here about a month ago regarding some issues about chain skip (http://www.bikeforums.net/showthread...1#post14291182)
I haven't been able to completely rid myself of it. The problem seems to be only in 7th gear (11-28 cassette). With the "B" adjust set to one end, I seem to get no skips when riding on flat ground. At the other end of adjustment, I get very occasional skips (no obvious pattern tied to links or cassette/crank rotation...tho it may be because it's not obvious And these particular skips don't seem quite like skips. Almost as if the chain momentarily hesitates to settle back onto the 7th gear (if that makes any sense). However, if I "stand" on the cranks when going up a hill or over a bridge, I definitely notice a nasty skip.
I have adjusted (and readjusted) the derailleur and can't quite completely eliminate the skip. Chain and cassette are now about a month old (brand new when this all started). I have adjusted Hi/Low limit screws as well as the adjusters at both the derailleur and shifter (shifter is Shimano SIS). Shifting is crisp (easily within 1/2 pedal stroke) up and down.
I know the standard procedure is to adjust the "B" screw so that the "jockey" pulley (one closest to the cassette) barely clears the lowest (in my case, 28T) gear. However, I can't tell any difference when I adjust this screw (other than a bit more tension).
I never had this problem before. The 2 things I changed are: 1. New jockey pulley - old one had a lot of side-to-side and up and down play in it (still not convinced it was worn out...tho with over 18K miles...maybe). May have caused some "slow" shifting from 6th to 7th gear, but never any skipping. 2. Cassette - Got a "low end" replacement (supposedly Shimano, but it only says that on the lock ring) because it's not easy to find 7spd, 11-28 cassettes these days. The chain is new, but it's the same chain I had on the bike.
I'm tempted to think it's the cassette. I may reinstall the old pulley. I will go back and try some more adjustments on the "B" screw and see if that makes it better (before I start tearing the rear section apart again).
I would welcome any insight or suggestions anyone can offer (my frustration is starting to build....)
Thanks and cheers....