External Bottom Brackets

Bought new external BB about 4 months ago as the first one developed alot of play and tore itself apart when I took the cranks off the service them. Same thing just happened again. The plastic sealed bearing sort of fuses to the crank axle and comes out of the bb cup when I try to take off the cranks.
A tiagra bb should last longer than 4 months, surely? what might I be doing wrong? Would buying 105 or ultegra make much difference?

Last time I asked about this you were all very funny, this time any advice appreciated.
Thanks

dont take the cranks off then.

reminds me of those tommy cooper jokes

Doctor it hurts when I do this!
Dont do that then.

Doctor I broke my arm in three places!
Well dont go back to those places

if only life were that simple. Cranks have to come off to keep threads clean, or they start creaking

External BBs are simple to deal with. Follow this carefully, you're missing a step or something.
http://www.parktool.com/blog/repair-help/external-bearing-crank-systems-hollowtech-ii-megaexo-giga-x-pipe-x-type-campagnolo-ultra-torque

"If spindle appears to catch and will not come out non-drive side cup, may be an indication that shell faces need machining. Grease splines of spindle and install left arm. Notice splines are keyed, and left arm will only install 180-degrees opposite of right arm. Grease threads of arm cap and thread cap into spindle. This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle. IMPORTANT NOTE: Secure cap gently. Use the eight sided stud a the end of the BBT-9 and tighten only 4 to 6 inch-pounds. Over tightening will side-load the bearing and cause premature wear. Spin arm to test."

Yes. A Tiagra BB should last longer than four months.

Probably dumb questions, but a good place to start: assume you greased / anti-seized the crank axle?

And:

IIRC hollotech 2 is very sensitive to the torqing used when installed - did you use a torque wrench?

I've been using Hollowtech 2 BBs for about 3 years now without problems. In fact, I believe the original Tiagra BB that came on my 2008 Specialized Allez is now on my Fixei skiddeh

User error.

Hippy, thanks, I'm sure I followed all that on installation. It is the drive side cup that stuck to the crank axle, non drive side is intact, though not running all that smooth.

Howard, yes, everything well greased on instsallation. I have been told never to use high pressure spray lube or anti sieze on bb cups as any ingression of it into sealed bearing opens them up. No, did not use tourque wrench on non drive side bolts. I asked at evans, they said just do it up evenly (alternate half turns on each) and tightly, it would be impossible top overtighten it they said. Should have ignored them and bought the tourque wrench I guess. So do you think I over or undertightened the nuts on non drive crank?

Over tightening the arm cap? Only needs to be finger tight.

Hmmm. If you've gone through two BBs already, with the drive side cup getting wrecked each time you've taken it apart maybe the cups aren't aligned (similar to the effect you get if they aren't torqued correctly I think).

Was the first one factory fitted? If so the BB shell might need squaring up to get the cups to align correctly. If not they probably aren't torqued right; it's not like a cartridge where you can just do it up as tight as you can - IIRC the campag ones are done up 'finger tight' with threadlock.

Or I could be talking bollocks - sure someone will come along with a definitive answer.

bb shell needs facing

I think they're complete shit.
Square taper FTW!

They certainly aren't KISS.

adoubletap, no its not the arm cap.

I think cup alignment may be the problem, so should I get the bb shell faced, would that sort it? How much does that cost? (frame is worth very little, need new bike really, threads stripped on rack mounts and bottle cage rivets are loose...) Also noticed there's a huge amount of crap inside the shell and the cup, I have been doing lots of long wet rides, possibly total of 2000 miles on it, but shouldnt it be water tight?

+1 to bb shell needs facing

Old frames were not made with the precision required for external BB, hence why you keep destroying the BB'S.

Old steel stuff is shit!

^this is a 2008 aluminium cross bike. I have a feeling you knew this...

Walked into Evans today and they'll face n chase for £30 if the crankset and bb is already in place, or £15 if you walk the bike in with no BB installed.

Alternately you could borrow a facer, does anyone know if anyone has got one? I might need one too.

Where do you live?

If in London try http://www.cyclelab.co.uk/

Good mechanics and cheaper labour than most shops and all chain stores.

Cool will check them out, thanks.

Never experienced that on any of my or bikes nor any of my customers.

Must have worked on several hundred external bb bikes now and they have all came apart as they should or at most needed a thump from the butt of my hand on the bb axle end.

Old frames were not made with the precision required for external BB, hence why you keep destroying the BB'S.

Old steel stuff is shit!

Ironically the BB thread modern frames use is the one from old british steel bikes!

The plastic spacing bush that sits between inner bearing surface & crank axle are often made of shit grade plastic. What happens over time is the oil/ grease/ anti-seize that you have pasted your axle in, have infact, been swallowed up by the plastic bush and swell onto the axle.

Older suspension forks used to do the same thing, the very oil thats meant to lubricate & damp them, actually made all the plastic components swell up and seize, jokes eh!

Get a shimano XT or ultegra grade EXT BB or try and find one of the higher end RaceFace or Hope ceramic or stainless bearing BB's. They will last a proper amount of time, though you pay for that, just like anything. Some EXT BB's don't have the plastic spacer, just axle > bearing surface, but obviously, in England, not a great idea.

Also can't stress enough how important facing the BB shell is. Essentially if you don't get it done*, expect trouble, nothing less.
*and done by someone who knows what they are doing

Even a 2008 frame may not have been faced if it wasn't sold with an external BB from new.

I fitted an Ultegra BB to my cross bike and it stills runs like new after a years use in all weathers and conditions (it is my only bike and used for everything), hosed down each weekend etc,.

I don't however remove the chain set and it never creaks. What threads start creaking on an external BB chainset?

Shouldn't creak. Anti seize on 2 locking bolts, bb cup threads and check out chain ring bolts for tightness/creak.
Could be more serious, could be something about to fail, always worth checking out.

the tolerance shim bb's and cranks are made to is tight

first face chase the bb

degrease the threads

antiseize all threads

install bb with correct spacing and to the right torque ~40nm drive side tightend first

clean of exess antiseize

film of grease all over crank axle

push crank through bb should go through by hand ... no hammering, even by hand!

retract crank slightly and wipe of lip of grease between bb seal and spider ... stops crap biulding up

push crank back in

install non drive side checking that saftey tap is in position

tighten plastic or ali end cap into axel by hand.

back it off

use torque wrench to tighten it to 2.5-3nm usualy off the scale of most home torque wrenches. might also need an icetools tool which uses a 8mm allen key to drive it.

tighten the pinch bolts evenly to 12-14nm

evenly means tigthtening progressivly there is no need to half a turn on each

wipe of an mis grease / antiseize

check pinch bolts and gunk biuld up every 2 weeks - month
dependant on how much riding / dirt you get up to.