While pedaling new shoes on rollers I noticed a slight feeling in my feet as I pedaled- a light clunk that occurs in a different crank position every revolution. Put the bike on a stand, and if I grab the rear wheel and turn the crank, I can feel in my hands the chain striking the cogs, but I also feel the clunk about once every 1/3 rotation. Is this normal, and I just never noticed it before?
It'a s Shimano Ultegra/600 groupo from the early 90's with maybe 2000km's on it. 8-speed STI shifting on an HG cogset, dual crank.
I notice that the clunk feeling seems to happen when the chain settles onto the cog beside where the ramps meet the teeth.
Took the bike 2 LBS. One turned the pedals like I did and said it's normal chain running. The other tightened up the usual suspects- crank bolts, chain ring bolts, pedals to the cranks, but no change, and told me not to worry about it.
Well, I am. I never noticed this in many hours of roller riding, and I hate wearing out parts from mis-adjustment.
I did some work to locate the source of the clunky feeling:
- compared small/large chain ring (for wear- the large cog has very little wear)
- measure the derailer/cog alignment to rule out bent derailer hanger
- ran the derailer through its indexing range by loosening/tighting the adjuster
- replaced with fresh cogset
- replaced with new 7.1mm wide chain
- replaced the freehub (it was slightly loose and wouldn't take the 11-tooth cog without some filing)
- wrapped another new chain, bypassing the derailer
- drank a beer, smoked a bowl, turned the cranks reeeallly slloooowly, sooooo sloooowly....woah, man...
Anyway none of these steps has changed the light clunky feeling. But the drivetrain looks great.
I have 3 other Shimano-equipped bikes, but I don't feel the light clunk on them like I do on this one. They have a lot more wear on them than this one.
Any thoughts?
It'a s Shimano Ultegra/600 groupo from the early 90's with maybe 2000km's on it. 8-speed STI shifting on an HG cogset, dual crank.
I notice that the clunk feeling seems to happen when the chain settles onto the cog beside where the ramps meet the teeth.
Took the bike 2 LBS. One turned the pedals like I did and said it's normal chain running. The other tightened up the usual suspects- crank bolts, chain ring bolts, pedals to the cranks, but no change, and told me not to worry about it.
Well, I am. I never noticed this in many hours of roller riding, and I hate wearing out parts from mis-adjustment.
I did some work to locate the source of the clunky feeling:
- compared small/large chain ring (for wear- the large cog has very little wear)
- measure the derailer/cog alignment to rule out bent derailer hanger
- ran the derailer through its indexing range by loosening/tighting the adjuster
- replaced with fresh cogset
- replaced with new 7.1mm wide chain
- replaced the freehub (it was slightly loose and wouldn't take the 11-tooth cog without some filing)
- wrapped another new chain, bypassing the derailer
- drank a beer, smoked a bowl, turned the cranks reeeallly slloooowly, sooooo sloooowly....woah, man...
Anyway none of these steps has changed the light clunky feeling. But the drivetrain looks great.
I have 3 other Shimano-equipped bikes, but I don't feel the light clunk on them like I do on this one. They have a lot more wear on them than this one.
Any thoughts?