Bottom bracket tools and tightening procedure..

wafter

Über Member
Location
Oxford
The (I assume BSA) threaded / Hollowtech BB on my Genesis continues to creak under load and the place it came from is miles away so it won't be going back unless there's a serious fault. I've checked that the pedals aren't responsible and can only assume the noise is either coming from movement between the BB cups and frame, bearings and BB cups or from the bearings themselves.

The cups don't feel loose in the frame (when checking by hand) but I figure it might be worth checking tightness with a tool / having the cups out for inspection / re-greasing.

So, first thing is that I need a tool. I prefer the idea of the socket-type items like this Lezyne item as they're deeper so should give more engagement / less chance of slipping or damage...

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However, I appreciate that there are advantages to the "wrench" format; namely that it can (presumably) be slipper over the non-drive-side crank arm to check the bearing cup tightness without the need to remove the arm..

1600759381255.jpeg



This brings me onto my next question.. I know the outboard BBs are considered to have an inferior life to square-taper alternatives due to a greater potential for mis-alignment of the cups in the frame. Does anyone think there's any mileage in the idea of fitting the cups to the frame in the normal way, but leaving the NDS cup loose and tightening it with the crank installed in an effort to promote some alignment between the two bearing cups?

I have a sneaking suspicion that the noise in my BB is due to shafted bearings, in which ase I'm not at all impressed that they've only lasted about 2k miles and would obviously like to prevent this happening again in future if possible..

Thanks :smile:
 
not at all impressed that they've only lasted about 2k miles
Suck it up. Seems to be quite typical IME. Left cup always fails first, i have a draw full of useable used RH cups.....
 

dave r

Dunking Diddy Dave Pedalling Pensioner
Too answer one of your questions, my Eastway has Hollowtech and my Genesis has square taper, the life is very similar, both bikes are about five years old and are on their second bottom bracket.
 
OP
wafter

wafter

Über Member
Location
Oxford
Suck it up. Seems to be quite typical IME. Left cup always fails first, i have a draw full of useable used RH cups.....
Bugger that - if this is typical it's bloody shameful and there has to be a better way. Interesting you mention that the LH side fails first; it seems that my LH one is the noisier of the two but then I'm also left-side-dominant (so probably further exacibating this issue). Can't be arsed to think about it too much but I suspect there's a leverage issue at play given the relative position of the chainrings that means the LH bearing is subject to more loading.

If it does turn out to be a "legitimately" failed BB and I get no joy from the suppliers (I can see the "they all do that mate" email now :rolleyes:) I think I'll look at getting the BB shell faces trued and fitting a Hambini BB, which seems to go some way to addressing the system's inherent potential for misalignment.

Too answer one of your questions, my Eastway has Hollowtech and my Genesis has square taper, the life is very similar, both bikes are about five years old and are on their second bottom bracket.
Thanks - do you know what mileage each has covered? I reckon mine started making noise at about 1500 miles, yet the square-taper item on my old Giant was still going with zero complaints (if a shade of lateral play in the crank arms) at 6k+ miles. Hurrah for "progress"....


Ranting aside does anyone have any thoughts on tools or fitting procedure as per my OP, please...?
 

ianrauk

Tattooed Beat Messiah
So, first thing is that I need a tool. I prefer the idea of the socket-type items like this Lezyne item as they're deeper so should give more engagement / less chance of slipping or damage...
This...
I have both tools and much prefer the socket type as it doesn't mark the new BB when installing whereas the thinner wrench type does. Also used with a much bigger wrench, getting an old BB off is far easier.

Over the years I have found that there's no rhyme or reason as to the life of external BB's. I have some that have lasted many thousands of miles, some that have given up the ghost far quicker.
 

dave r

Dunking Diddy Dave Pedalling Pensioner
Bugger that - if this is typical it's bloody shameful and there has to be a better way. Interesting you mention that the LH side fails first; it seems that my LH one is the noisier of the two but then I'm also left-side-dominant (so probably further exacibating this issue). Can't be arsed to think about it too much but I suspect there's a leverage issue at play given the relative position of the chainrings that means the LH bearing is subject to more loading.

If it does turn out to be a "legitimately" failed BB and I get no joy from the suppliers (I can see the "they all do that mate" email now :rolleyes:) I think I'll look at getting the BB shell faces trued and fitting a Hambini BB, which seems to go some way to addressing the system's inherent potential for misalignment.


Thanks - do you know what mileage each has covered? I reckon mine started making noise at about 1500 miles, yet the square-taper item on my old Giant was still going with zero complaints (if a shade of lateral play in the crank arms) at 6k+ miles. Hurrah for "progress"....


Ranting aside does anyone have any thoughts on tools or fitting procedure as per my OP, please...?
Riding 4-5000 miles a year split between 2 bikes, I can't remember exact mileage but somewhere between 5000 and 7000 miles.
 
OP
wafter

wafter

Über Member
Location
Oxford
BB s are cheap, cheaper than many chains. Not many grumble about replacing a chain after 2,000 miles. Having said that, my Shimano hollow tech 2 BB is currently at 6,000 miles and still going strong.
True, but IMO that's beside the point if they're failing well before their design life would suggest.. and as it happens I reckon my chain's only at about 2-3% wear so I'm expecting 4-5k from it :smile:

It's heartening at least to hear that your BB is behaving itself so proves that under appropriate conditions they can last :smile:

This...
I have both tools and much prefer the socket type as it doesn't mark the new BB when installing whereas the thinner wrench type does. Also used with a much bigger wrench, getting an old BB off is far easier.

Over the years I have found that there's no rhyme or reason as to the life of external BB's. I have some that have lasted many thousands of miles, some that have given up the ghost far quicker.
Thanks - I appreciate your input and confirmation of my thoughts; looks like a socket-type tool is on the shopping list then :smile:

Have you found wildly different life between the same model of BB on the same frame? It seems that the biggest issue with external BBs is dodgy alignment due to poor squareness on the register face on each side of the BB cup; which could easily be caused by uneven paint buildup during finishing.. so from this I'd expect poor longevity to be associated with particular frames rather than the BBs themselves (assuming they're from a reputable source and Shimano seems to be good on the whole.

That said I'm also wondering if there's also some variability in positional repetability even when removing and refitting the same cups to the same frame; which to an extent might be remedied by tightennig the NDS cup with the axle fitted. Not sure how viable this would be when using a socket type tool, although I I was really keen I guess I could always source a bit of ground bar stock to fit the IDs of the bearings to use as an alignment tool.

Riding 4-5000 miles a year split between 2 bikes, I can't remember exact mileage but somewhere between 5000 and 7000 miles.
Thanks - that sounds like good service from both and I'd be very happy if mine would reach such distances without complaining!
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
BB's will creak if not really tight. GXP has to be chuffing mega tight (40 mn or something)

BB's are cheap to replace and if you've not popped the seals and re-greased the BB, then they can fail (unlike square taper). SRAM GXP is notorious for not lasting, but at £20 a pop, I can live with replacements every 2 years on a MTB - TBH, I bought a Praxxis Works GXP for £32, and it's miles better.

The bearings alone for Hollowtech/GXP are nearer £10 each, so it's as cheap to replace the lot.

Shimano BB's are pretty good TBH, so stick with them.

Thank goodness you don't have press fit.
 

faster

Senior Member
This brings me onto my next question.. I know the outboard BBs are considered to have an inferior life to square-taper alternatives due to a greater potential for mis-alignment of the cups in the frame. Does anyone think there's any mileage in the idea of fitting the cups to the frame in the normal way, but leaving the NDS cup loose and tightening it with the crank installed in an effort to promote some alignment between the two bearing cups?
I don't think that would make any difference - the cup will end up in the same place.

I have a sneaking suspicion that the noise in my BB is due to shafted bearings, in which ase I'm not at all impressed that they've only lasted about 2k miles and would obviously like to prevent this happening again in future if possible..

Thanks :smile:
Hollowtech bearings are very good in my experience. The most likely explanation for your failure in my experience is that it was installed incorrectly. People seem to think because Shimano supply that little plastic tool, you should preload the bearings with it as tight as you can with the tool. The correct amount of preload (on plastic bolt on the NDS) is about zero - just enough to remove any play.

Just make sure the crankset is well seated by giving it a few taps from the drive side, then turn the plastic adjuster until there is the slightest resistance, then a tiny bit more (as little as you can manage) and you're done (the NDS crank will still be wobbly until the pinch bolts are tight). Don't be tempted to tighten it up until it is finger tight.

For reference, the HT2 BB on my commuter has done over 10,000 all weather miles with no maintenance whatsoever and is still absolutely fine. The one it replaced (which was tight to turn from the off on a new bike) managed about 800 miles.

Buy the socket type tool.
 
OP
wafter

wafter

Über Member
Location
Oxford
Thanks all!

BB's will creak if not really tight. GXP has to be chuffing mega tight (40 mn or something)

BB's are cheap to replace and if you've not popped the seals and re-greased the BB, then they can fail (unlike square taper). SRAM GXP is notorious for not lasting, but at £20 a pop, I can live with replacements every 2 years on a MTB - TBH, I bought a Praxxis Works GXP for £32, and it's miles better.

The bearings alone for Hollowtech/GXP are nearer £10 each, so it's as cheap to replace the lot.

Shimano BB's are pretty good TBH, so stick with them.

Thank goodness you don't have press fit.
Cheers - maybe it's just a case of them having worked a little loose during use but they're certainly well-beyond hand-tight and tbh I'd have expected them to tighten with use if owt. I think before whinging to the supplier I might just whip them out, re-grease them and re-torque them though (although might still drop them a line actually to verify that this won't void my warranty and give them a convenient get-out).

What do you recommend in terms of grease? I usually default to moly-disulphide for high-load dynamic stuff (as used in CV joints on cars so should be grand on bearings, effect on efficiency of viscousity notwithstanding) and was thinking anti-seize copper grease on the cup threads and register faces..

Thanks for the thought on bearings; unlike most suppliers I generally trust Shimano products so would happily go with them if continuing with standard components. I'll be interested to see what sort of bearings are fitted and may be tempted to try and replace the bearings alone if they're no-name specials; although I'd expect them to be half-decent on Ultregra-level kit. Plus, I don't have access to a press so getting them in and out could prove difficult..

I lol'd at your comment about press-fit as I my road bike is PF30 and one of the draws to threaded was its perceived superior longevity. While I've only put about 1800 miles on the road bike and about 2.1k miles on the Genesis, ironically so far (and touch wood!) the BB on the road bike has been fine :laugh:

I don't think that would make any difference - the cup will end up in the same place.

Hollowtech bearings are very good in my experience. The most likely explanation for your failure in my experience is that it was installed incorrectly. People seem to think because Shimano supply that little plastic tool, you should preload the bearings with it as tight as you can with the tool. The correct amount of preload (on plastic bolt on the NDS) is about zero - just enough to remove any play.

Just make sure the crankset is well seated by giving it a few taps from the drive side, then turn the plastic adjuster until there is the slightest resistance, then a tiny bit more (as little as you can manage) and you're done (the NDS crank will still be wobbly until the pinch bolts are tight). Don't be tempted to tighten it up until it is finger tight.

For reference, the HT2 BB on my commuter has done over 10,000 all weather miles with no maintenance whatsoever and is still absolutely fine. The one it replaced (which was tight to turn from the off on a new bike) managed about 800 miles.

Buy the socket type tool.
Thanks - perhaps you're right about the cup location.

Ta for the thought about the preload - that's not even something I'd considered tbh but certainly worth looking at.. will add a tool to the list as of course I'd need one anyway. Your preload procedure makes sense and is the approach I'd have chosen. Tbh though the rest of the bike seemed pretty well built up, so this may or may not be an issue.

You make a compelling argument for the importance of preload so finger's crossed it's something this simple and I don't have to resort to re-facing the BB shell!

I would back up a little and make sure it is the BB that is to blame. Check you fittings elsewhere before you buy tools, things like QRs, seatpost, saddle, stem, bars etc.
Ta - although I'm pretty sure it's the BB as it sounds like it's coming from there / typical of a BB issue and does it when both in and out of the saddle; so at least rules out anything saddle-related. The bike has TAs (which are fine) so no QRs to worry about and the pedals have already been canged, lubed and torqued with no descernible difference.

Besides, skint as I am the tools won't break the bank and I'll need them sooner or later so don't begrudge spending a few more quid on filling the toolbox a little more :smile:
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Certainly whip the cups off, coppa slip the threads, back on tight, and then use grease on the bearings. Any will do, but one that withstands water - CV joint should be fine.
 
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