Weird drivetrain issue - advice please
Discussion
Something very odd is happening to my bike. It selects gears okay and has no trouble holding them, but it's as if the drag of the driveline varies from sprocket to sprocket. It can actually be easier to pedal in a higher gear (maintaining the same cadence etc.)
Additionally, the whole bike feels hard going, a bit like cycling into a permanent head wind. It seems to freewheel okay, but pedaling is hard work.
Any thoughts? The bike hadn't been used much for a few weeks until I got back into it on Monday, but I honestly think it's the bike rather than me. It's had a new chain, front chain ring and bottom bracket recently and I think something's gone awry with one of them. The only thing I noticed on a quick check is that the chain lube appears to have gone off and led to a rather unpleasant coagulated mess - maybe more of this is deposited on the first six gears than the remaining three or something.
Additionally, the whole bike feels hard going, a bit like cycling into a permanent head wind. It seems to freewheel okay, but pedaling is hard work.
Any thoughts? The bike hadn't been used much for a few weeks until I got back into it on Monday, but I honestly think it's the bike rather than me. It's had a new chain, front chain ring and bottom bracket recently and I think something's gone awry with one of them. The only thing I noticed on a quick check is that the chain lube appears to have gone off and led to a rather unpleasant coagulated mess - maybe more of this is deposited on the first six gears than the remaining three or something.
You should be able to find the cause yourself by trying to eliminate things one at a time.
Dodgy bottom bracket. Check for play in the bearings by holding one or both crank arms and pushing from side to side – toward the bike frame and away from the bike frame. I know you said it was new, but might not have been fitted correctly, or be faulty.
Another check on bottom bracket would be to drop the chain off the granny ring and spin the crankset. Does it spin freely with no wobbles, grinding sounds, slowing. Should spin as smooth as. Wonky alignment, or dodgy bearings could cause drag under the flex from high pressure pedalling loads.
Simple check on wheel bearings – do both wheels spin freely and smoothly? Test with a side-to-side wobble to see if there is any play. Small amounts of play may get much worse when pressure is put on the rear especially, during hard pedalling, causing drag of dodgy bearings, or drag from the brake rotor rubbing the pads?
Check the freewheel. Drop the rear wheel out and spin the rear cassette with your hand. Does it spin freely and the clicks of the freewheel sound crisp…no funny grinding noises?
Check the jockey wheels of the rear mech. Do they spin freely? There might be a bit of side-to-side play in the bearings (depending on type and spec of the mech) which is usually OK, but lots of play might cause problems under heavy pedalling pressure?
Pedal bearings OK? Do the pedals spin freely? Again, pressure from hard pedalling might be causing drag on the pedal bearings?
Chain OK? Give it a thorough clean and check each link moves freely with your hands… just try and flex each link after you’ve cleaned the chain (or prepare to get oily fingers!).
Not found the problem? Then take it to your LBS and admit defeat!
Dodgy bottom bracket. Check for play in the bearings by holding one or both crank arms and pushing from side to side – toward the bike frame and away from the bike frame. I know you said it was new, but might not have been fitted correctly, or be faulty.
Another check on bottom bracket would be to drop the chain off the granny ring and spin the crankset. Does it spin freely with no wobbles, grinding sounds, slowing. Should spin as smooth as. Wonky alignment, or dodgy bearings could cause drag under the flex from high pressure pedalling loads.
Simple check on wheel bearings – do both wheels spin freely and smoothly? Test with a side-to-side wobble to see if there is any play. Small amounts of play may get much worse when pressure is put on the rear especially, during hard pedalling, causing drag of dodgy bearings, or drag from the brake rotor rubbing the pads?
Check the freewheel. Drop the rear wheel out and spin the rear cassette with your hand. Does it spin freely and the clicks of the freewheel sound crisp…no funny grinding noises?
Check the jockey wheels of the rear mech. Do they spin freely? There might be a bit of side-to-side play in the bearings (depending on type and spec of the mech) which is usually OK, but lots of play might cause problems under heavy pedalling pressure?
Pedal bearings OK? Do the pedals spin freely? Again, pressure from hard pedalling might be causing drag on the pedal bearings?
Chain OK? Give it a thorough clean and check each link moves freely with your hands… just try and flex each link after you’ve cleaned the chain (or prepare to get oily fingers!).
Not found the problem? Then take it to your LBS and admit defeat!
Smartboy said:
You should be able to find the cause yourself by trying to eliminate things one at a time.
Dodgy bottom bracket. Check for play in the bearings by holding one or both crank arms and pushing from side to side – toward the bike frame and away from the bike frame. I know you said it was new, but might not have been fitted correctly, or be faulty.
Another check on bottom bracket would be to drop the chain off the granny ring and spin the crankset. Does it spin freely with no wobbles, grinding sounds, slowing. Should spin as smooth as. Wonky alignment, or dodgy bearings could cause drag under the flex from high pressure pedalling loads.
Simple check on wheel bearings – do both wheels spin freely and smoothly? Test with a side-to-side wobble to see if there is any play. Small amounts of play may get much worse when pressure is put on the rear especially, during hard pedalling, causing drag of dodgy bearings, or drag from the brake rotor rubbing the pads?
Check the freewheel. Drop the rear wheel out and spin the rear cassette with your hand. Does it spin freely and the clicks of the freewheel sound crisp…no funny grinding noises?
Check the jockey wheels of the rear mech. Do they spin freely? There might be a bit of side-to-side play in the bearings (depending on type and spec of the mech) which is usually OK, but lots of play might cause problems under heavy pedalling pressure?
Pedal bearings OK? Do the pedals spin freely? Again, pressure from hard pedalling might be causing drag on the pedal bearings?
Chain OK? Give it a thorough clean and check each link moves freely with your hands… just try and flex each link after you’ve cleaned the chain (or prepare to get oily fingers!).
Not found the problem? Then take it to your LBS and admit defeat!
Dodgy bottom bracket. Check for play in the bearings by holding one or both crank arms and pushing from side to side – toward the bike frame and away from the bike frame. I know you said it was new, but might not have been fitted correctly, or be faulty.
Another check on bottom bracket would be to drop the chain off the granny ring and spin the crankset. Does it spin freely with no wobbles, grinding sounds, slowing. Should spin as smooth as. Wonky alignment, or dodgy bearings could cause drag under the flex from high pressure pedalling loads.
Simple check on wheel bearings – do both wheels spin freely and smoothly? Test with a side-to-side wobble to see if there is any play. Small amounts of play may get much worse when pressure is put on the rear especially, during hard pedalling, causing drag of dodgy bearings, or drag from the brake rotor rubbing the pads?
Check the freewheel. Drop the rear wheel out and spin the rear cassette with your hand. Does it spin freely and the clicks of the freewheel sound crisp…no funny grinding noises?
Check the jockey wheels of the rear mech. Do they spin freely? There might be a bit of side-to-side play in the bearings (depending on type and spec of the mech) which is usually OK, but lots of play might cause problems under heavy pedalling pressure?
Pedal bearings OK? Do the pedals spin freely? Again, pressure from hard pedalling might be causing drag on the pedal bearings?
Chain OK? Give it a thorough clean and check each link moves freely with your hands… just try and flex each link after you’ve cleaned the chain (or prepare to get oily fingers!).
Not found the problem? Then take it to your LBS and admit defeat!
All good stuff, thanks.
The chain is indeed new - going back to a few of the posts above - but it's most noticeable when on a combination of large front sprocket, small rear sprocket. I do wonder if that gunk on the chain has something to do with it, though. I'm normally pretty good at de-greasing and lubricating chains, but this one hasn't been done for a while and it is fairly unpleasant.
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