Problems with rear derailleur
Picked up my first road bike, a 2000 Specialized Allez Sport A1. Bike appears to be in mint condition, however, I can't seem to get it to shift correctly. Here are the symptoms and what has been tried to fix it:
- When trying to index the rear derailleur I can get it to shift nice and smooth from the smallest ring to the biggest ring without issue. However, trying to shift back is where I run into a problem. After 1 click it's clear that the chain is not going to go down to the next smaller ring. Easing off the tension allows the chain to move, but it's not smooth and very often will skip 2 rings. Also, once I let out enough tension to get the chain all the way back down to the smallest ring, it lacks enough tension to go back up.
- It's a 17 year old bike so I assumed that there was some friction built up in the cables and housings. So I replaced them all, but with the exact same results.
- Finally caved and took it to a professional bike mechanic. He ran into the same problem I was running into. The hanger was bent but has been realigned (problem persists). Chain has plenty of life left in it. We also put a wheel on it from a used bike in the shop with the exact same component group and 9 speed cassette (problem persists). Checked frame alignment (spot on - no issue there). Shifters appear to be in perfect working order. Visually, the cassette looks to be in perfect working order. All signs point to a bike with very low miles on it.
At this point I'm not sure what to try next. The mechanic suggested getting a new derailleur even though the one on there appears to be in good shape. Next he suggested a new cassette and chain to see if that is the problem for some reason (even though chain is in great shape and cassette 'appears' to be in good shape as well).
I don't have any problems with these suggestions but want to make sure I'm not going to blow more money on this thing unnecessarily. Is there anything else I should be trying before replacing those parts? Is it possible that the old barrel adjusters on the downtube are causing friction? They aren't particularly smooth when trying to turn them.