Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at firstname.lastname@example.org.
Question: My 2008 Felt f75 with about 8k miles begin developing shifting problems. Primarily it would hang shifting from 6th to 5the gear. The problem was not replacing the original chain. OK..I learned my lesson and will change every 2k from this day forward. The damage was done, so my cassette and chainrings were also worn. I replaced the crank, cassette and chain with Ultegra 10 speed units. Still I was having problems shifting down to 6th. I took it on my own to replace the rear derailleur, and at the LBS recommendation the shifters and cables, also Ultegra. The LBS did this intalation. I still can’t tune this out with the barrel adjuster at the derailleur. I am pretty good at tuning the derailleur if everything thing is as it should be, but now I’m stumped. Could this be a worn freewheel or hub? I did use the old chain for several hundred on the new cassette before I replaced the chain and crank. From: Ed
Answer: This is a really strange one Ed, but I have a few ideas of what could be wrong. Here is a list of possible problems:
- Missing and/or wrong cassette spacers
- Asymetrical chain installed backwards
- Loose cassette lockring
- Loose derailleur hanger
- Misaligned derailleur hanger
- Loose hub/bad freehub bearings
My last diagnostic tool/fix would be to place a 1/16″-3/32″ thick washer (common 3/8″ diameter washer found at a hardware store) between the derailleur hanger and derailleur fixing bolt to see if that moves the problem to the next cog or solves it all together. If it solves it, then your setup might just require a bit more spring tension in the derailleur to pull the chain down to a smaller cog and rule out any cassette issue.
I conferred with my associate Lennard Zinn at VeloNews about your problem and he offered this advice: “Is this a bike with internal shift cables? If so, the two cables might be crossed inside.”
Check all this over and let me know how it goes.
Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.