Those marks to my understanding come from the crank arm is rotating while the bearing doesn’t move. I’d check your bearings and make sure they are rotating freely. If they are not you need a new bb. If they are it is possible that your bottom bracket is misaligned. That’s my understanding of this at least take it with a grain of salt as it’s not a problem I have personally had.
ArmyFork on
That’s caused by axial (in/out) movement of the axle relative to the bearing, while there is always some it does seem that’s a touch high. Would be worth checking that the plastic washer you referred to in a different comment is not worn, I would also inspect the bottom bracket for wear as well. I’m not super familiar with this crankset (SRAM Dub?), but there may not have been enough preload on the cranks as well, ensure that it is preloaded to spec when it’s reassembled.
justburningaccount on
Undersized bottom bracket shell on one side. Squeezes the bearing and causes it to under-rotate
Nike_486DX on
Anodized aluminum sitting on steel bearing? This is normal (but the engineering is not that good). Shimano uses plastic sleeve that slows this wear like 3 times if not more.
And once it goes through tough anodization, its gonna be like caries, cuz bare aluminum is very soft.
6 Comments
Blown out bearing or a loose preload adjuster.
Same happens to me, tis but a scratch.
Those marks to my understanding come from the crank arm is rotating while the bearing doesn’t move. I’d check your bearings and make sure they are rotating freely. If they are not you need a new bb. If they are it is possible that your bottom bracket is misaligned. That’s my understanding of this at least take it with a grain of salt as it’s not a problem I have personally had.
That’s caused by axial (in/out) movement of the axle relative to the bearing, while there is always some it does seem that’s a touch high. Would be worth checking that the plastic washer you referred to in a different comment is not worn, I would also inspect the bottom bracket for wear as well. I’m not super familiar with this crankset (SRAM Dub?), but there may not have been enough preload on the cranks as well, ensure that it is preloaded to spec when it’s reassembled.
Undersized bottom bracket shell on one side. Squeezes the bearing and causes it to under-rotate
Anodized aluminum sitting on steel bearing? This is normal (but the engineering is not that good). Shimano uses plastic sleeve that slows this wear like 3 times if not more.
And once it goes through tough anodization, its gonna be like caries, cuz bare aluminum is very soft.