On Thursday, October 4, 2018 at 8:04:02 PM UTC-5, jbeattie wrote:
On Thursday, October 4, 2018 at 2:08:36 PM UTC-7, wrote:
On Tuesday, October 2, 2018 at 1:10:59 PM UTC-5, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.

-- Jay Beattie.

Check the rear derailleur hanger for straightness. Bent rear derailleur hangers can cause mis-shifts at one end of the cassette and be OK in the middle or other end.

I'll do that. I put on a new hanger when I switched from the Specialized SCS system -- but it worked perfectly for a while. The chain is virtually new, and I'm starting to think that I also swapped out the cassette. I have an old 11sp sitting on the counter in the downstairs bike shop, and that's the only bike it could have come off. The problem happened literally overnight.

-- Jay Beattie.

A NEW hanger DOES NOT guarantee straightness. A new hanger has to be bent into straightness just like an old bent hanger.