Chain slipping on just the smallest sprocket
Twelly
Posts: 1,437
Just finished renovating the girlfriends old bike. It's an early 90's generic womens rigid. The only markings before I resprayed it were 'Trailblazer' on the down tube. Trust me, this thing does not blaze trails...
Anyhoo, last week I stripped the 3x6 drivetrain - both mechs, chainset, BB, chain all taken off, disassembled, degreased, reassembled and lubed up. Also replaced BB bearings and both gear cables while it was all apart.
I indexed the shifting and it now changes quickly and smoothly through all gears as it should but when it is in the smallest cassette sprocket, the chain jumps whenever any reasonable torque is applied through the cranks (i.e. when standing or pushing up a hill) This only happens with this sprocket and it happens regardless of which front chain ring is being used. The high/low stops are set up perfectly and the indexing is spot on.
From what I can see, there is no teeth missing and no out of the ordinary wear on that sprocket, certainly no more than any of the others.
Any ideas?
EDIT: It's generic Shimano hardware, no markings other than Shimano on rear mech. SRAM PC90 chain. Cassette is a generic 6spd, no markings.
Anyhoo, last week I stripped the 3x6 drivetrain - both mechs, chainset, BB, chain all taken off, disassembled, degreased, reassembled and lubed up. Also replaced BB bearings and both gear cables while it was all apart.
I indexed the shifting and it now changes quickly and smoothly through all gears as it should but when it is in the smallest cassette sprocket, the chain jumps whenever any reasonable torque is applied through the cranks (i.e. when standing or pushing up a hill) This only happens with this sprocket and it happens regardless of which front chain ring is being used. The high/low stops are set up perfectly and the indexing is spot on.
From what I can see, there is no teeth missing and no out of the ordinary wear on that sprocket, certainly no more than any of the others.
Any ideas?
EDIT: It's generic Shimano hardware, no markings other than Shimano on rear mech. SRAM PC90 chain. Cassette is a generic 6spd, no markings.
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Comments
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typical worn cog syndrome.
new block and chain time."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
nicklouse wrote:typical worn cog syndrome.
new block and chain time.
I thought as much.
I'm assuming any 6spd freewheel/chain combo will be suitable? or is there anything I need to look out for when choosing replacements?0 -
have you adjusted the limit screws on the rear mech to see if that helps? If you have and it's still bust, any 6spd freeewheel will do.....Shimano and Sunrace are the two you'll see most of - both VERY similar quality0
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Limit screws/cable tension/indexing is spot on. I guessed it may be a worn sprocket but because I can't see any obvious signs of wear, I thought I may have missed something.
Thanks guys.0
