Chain Not Sitting Right in "4" Only
I'm stumped.
For about a year, my vintage 1996 GT Outpost (the love of my life) has not been able to ride smoothly when I am on the fourth cassette ring. Occasionally, "5" and "6" are problematic, too, although not as bad.
The problem feels like the chain is not connecting with the ring quite right. It's not slipping and I don't really feel it rubbing against the adjacent ring. It just feels like the chain is missing the teeth by a minuscule amount, or like there's a piece of dirt stuck somewhere. Interestingly, I don't really hear it or feel it when the bike is on a workstand, but it comes back big time once it's back on the road. Here's what I have done so far:
1. Adjusted the derailleur barrel ad nauseum with hopes that it's just a tension problem
2. Replaced the chain
3. Replaced the cassette
4. Replaced the entire rear derailleur
5. Changed the pedals, thinking maybe I was wrong about where the problem was coming from
5. Tightened the cassette because I noticed it was a little loose today
I have also had the bike looked at by three different mechanics who can't seem to pinpoint the problem. All have told me not to worry, and to just keep riding it into the ground. (That's the problem when you insist on keeping an old bike on the road. Everybody treats it like your old grandfather who is dying of congestive heart failure. "Just keep 'im comfortable and make sure he enjoys the rest of his life.")
This bike has traveled thousands of miles with me and just got off two overnight rides to points out-of-state. I don't plan on hanging it up anytime soon. However, I am starting to not enjoy riding it as much because of this persistent problem.
One crazy idea I have is to replace the front triple chainring with a single so that the chainline has a better chance of running perfectly straight. Right now, the bike is a 3 X 7 and I almost never use anything but the middle ring.
Can anybody think of anything else**********