It sounds like this may be a complex problem. So yesterday I dropped off the bike at not-so-local bike shop. Today I called. Mechanic said he rode the bike & couldn't reproduce problem. So I drove back to not-so-local bike shop & took the bike home, changed out of suit, into shorts & rode down the block. I don't know if I am just imagining it, but I think the ratcheting is less. Could almost be gone. Now watch it return tomorrow.
Possible explanations: over cleaned/overlubricated chain, as cny suggested ? I will say that there is so much lube on it since bike shop service a few weeks ago that I am practically bathed in grease after a long ride.
One difference between riding today and previously is I haven't put the rack pack & saddlebags back on [for some reason I have kept the saddlebags on since the winter when I'd have to strip down the further I rode and needed a place for the extra layers ! But I checked and they were never touching the chain or derailleurs.
Maybe when I start my weekend ride the problem will be back - I don't know. I'll have to see.
I will keep all informed. All ideas are always welcome.
Babel .