Bicycle Mechanics - Problems with Crank
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04-18-08, 09:27 AM
Hi, I've been having problems with the crank of my bike. Last year, while riding it became very stiff to peddle, it got worse over time and now I cannot even use it because it feels like you are trying to go up a really steep hill when you are riding on flat land. We believe that the bearings need replacing, however is this a part that can be replaced or does the whole crank need to be replaced? We can get the tool from our friend to actually pull the crank apart, however I'm wondering if it would be best just to replace the crank its self. If any one has any suggestions or ideas that would be great, thanks.
Cranks should be fine. BB can be either loose or caged bearings which are replaceable.
A hint as to the likelihood of this would be whether square taper or hollow splined
BB spindle. Splined types are all sealed bearings. Sq taper come in both flavors. Disassembly is
usually straight forward with the right tools. If the bearings are loose/caged ball, then the
determining factor is what the bearing races look like. It takes a horrendous abuse to
'lock up' ball bearing (loose/caged) BB. OTOH sealed bearings BB will come out as a
single unit and in theory can be fixed but if locking up with high friction it generally means
either the original 'life time' lube has calcified or turned to paraffin or been washed out and
turned to mayonaise by water,corroding the balls/races and ruining the bearing. I had a
Phil Wood BB cartridge from ~1974 stored in a bike til `'99 and the BB couldn't be turned
by hand. I popped the seals off the bearing cartridges and washed out the grease turned
to wax, relubed, reinstalled the seals and rode the bike for several thousand miles before
bequeathing the Px10 to a brother for storage. Those with access to manual presses can
extrude the bearings, replace (they are standard sizes) for $3-5/bearing and reinstall.
The faint of heart or multithumbed can get a new BB for $30-40.
you probably don't need new cranks, it is almost definitely your bottom bracket that is having some problems. there are a couple of reasons this could be, but unless you really want to learn about repairing bikes, it's probably time to go to the bike store and get them to repair it for you? not to be patronizing, but it doesn't seem like you know the names of the various parts involved, and if you don't know the terminology you are probably not ready for this kind of repair.
in order to get into the bottom bracket to do the work it probably needs you will need a bunch of specialized tools, and you will end up spending as much or more than the shop would charge you for repair. it is definitely very satisfying to know how to do it yourself, and i'm not trying to discourage anyone who is interested from learning (it's not all that hard), but unless it is something that actively interests you it is better to leave to professionals, since there are some confusing elements and things that are pretty easy to screw up. if you are really interested in learning more maybe check out
04-19-08, 07:59 AM
Are you certain the problem is in the crank/bottom bracket area? It could be the rear hub or chain. Try to rotate the rear wheel alone. If it turns freely, the problem is with the crank or chain. Then slip the chain off the chainrings and turn the crank alone. That should isolate the problem.
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