External BB going a bit stiff sometimes

danlightbulb

Ive noticed recently (after a very muddy ride one day) that when left alone for a few days my bottom bracket stiffens up. After a few crank spins it frees up again.

Is this a concern?

nicklouse

it might be. strip and clean and if you dont know if the shell has been faced get it done.

check the bearings feel. if smooth then they are fine. pop the covers off and grease and re fit.

cooldad

Pop the covers off very gently - Shimano has a 'top hat' shaped cover over the bearings which is very thin and quite brittle.

mrmonkfinger

which BB?


it sounds like a clean + regrease is needed, remove the crank and pop the covers as per cooldads suggestion.

although if its stiffening up from any internal rust it suggests the bearings are on their last legs

danlightbulb

Shimano deore external bb. Bike only couple months old. Im not sure what you mean by covers? Dont i need a big bb spanner to remove it all?

cooldad

Nope you can just take the cranks off (allen key) and you will see the plastic covers over the bearings. Pop the covers off and then the bearing side plates.
BUT they are not intended to be serviceable and the covers are flimsy, so easy to crack. Ease out from the inside (where the axle goes) not the edges. Gently.
Once you get the cranks off the cup looks like (this is a road one but they look the same (unless it's XTR)


The bearing cover looks like this once you get it off (fragile)


The BB cup looks like this - just prise the side plate off (the blue bit), clean, regrease. (The actual bearings don't come out of the cups easily - I just leave them in)

cooldad

But as you can get a new BB for just over a tenner, it's probably easier to buy a BB tool and just replace them. I replaced Deore with XTR and it's lasted a hell of a lot longer.

danlightbulb

Thanks for the help, photos help alot. It might just be crudded up Ive never removed the cranks.

Does the Deore M590 BB have sealed bearings?

cooldad

Pretty much identical to the pics posted.

Erudin

Below is a pic of a SM-BB51 cup with "top hat" bearing cover removed that came with my M590 chainset, the bearings were rough before fitting and were close to seizing after a couple of wet rides on Dartmoor. Replaced the bearings with some Katec bearings (left in pic) from Ebay which I hope will last longer.

The Katec 6805 2rs bearings are 1mm wider than the originals so I used RaceFace X-Type Bottom Bracket Bearing Caps which have no lip to replace the Shimano ones which do, and left out the thin .7mm spacer on the left side.

The vids below are for replacing bearings in Hope bb cups, but the principles apply:

YouTube Link - Replacing hope bottom bracket bearings cheaply (same guy that sells Katec bearings)

YouTube Link - Hope Technology - Shimano Bottom Bracket (shows how to avoid side-loading the bearing)

http://faqload.com/faqs/bicycle-components/drivetrain/hollowtech-ii-outboard-bearing-service