Hi all,

I was here a while back in regards to problem with chain skip on my '99 Hardrock (http://www.bikeforums.net/showthread...=#post14201679).

I'm waiting for the new chain (on exchange and hope it will be in this week) but I had a thought about what I was experiencing and thought I might be able to get a bit more help (or insight). I reinstalled my old cassette and chain and discovered after a few rides it had developed some skipping issues, as well (I know...In my last email of the above link, I stated I had completely solved the problem...alas, not to be

I adjusted the derailleur (Hi, Low and "B" limits) which seemed to help, but not eliminate, the problem. I remembered there was one other thing I did which is where I could use some expert opinions.

Some time ago, I had purchased a new set (2) of 11T plastic "cogs" for the derailleur and decided to install those this time around (the old ones were worn but had not given me any problems). I noticed a difference between the old and new set. The old top cog seemed to have quite a bit of play in it. Unfortunately, I have no idea if it had always been that way (never looked closely until I had put 13K+ miles on the bike), but while there are signs of wearing and use, the amount is way beyond what I think wear and tear should be (maybe I'm just being naive' here). Based on my limited knowledge, it looks like it was by design given how much bigger the diameter of the bushing "race" was compared to the bushing it rotated on. The new top cog is much like the bottom one (both old and new). The bushing "race" is much closer in diameter to the bushing.

This is the original Acera-X or Alivio derailleur from 1999. I'm wondering if this unit was designed with the amount of "play" for shifting reasons. Or, with the new cog in there, the adjustments have become much more critical? Do I need to go back to the old top cog?

Thanks in advance for any help.

Cheers...Steph