My understanding was that the old type sealed internal BBs like the square taper would last for many years, so I fitted one to my converted SS commuting bike last year.
In that time I've been through 3, the first was a cheap £11 jobbie lasted 4m, so I though fair enough, I'll get a better one, so basic Shimano, lasted 3m, ok ill pay a bit more (£24) for a better Shimano one, 2 months!
Now I'm not heavy at 70kg, it's moderately hilly where I am, it's stored in a dry place, I don't know if it's because it's a singlespeed, but this just seems wrong.
Any thoughts?
How did the BB fail?
How often do you clean the bike and how?
You say its a singlespeed, how is the chain tensioned, its too tight would be my guess.
Rarely needs cleaning, low pressure garden hose and a sponge.
Chain tension is by a spring loaded chain tensioner device, about the same or less than a derailleur
Failing as in a loud click that can eventually be felt through the cranks (defo not pedals etc).
Personally I've done thousands of miles on Shimano ones without fault, even when abused on dh bikes, but that was a "few" years back. Broke a few crank arms, but never a BB.
These still seem happy with them
https://www.renehersecycles.com/why-square-taper-bottom-brackets/
Sounds like you've done everything right. In my experience Shimano cartridge bottom brackets last for 1000s of miles. The only possible thing could be tightening the non-drive side cup too much but that would only be a problem for the style of BB that use actual cartridge bearing separated by a spacer rather than the classic Shimano cartridge style where both bearing are integrated into a complete assembly, which has the advantage of removing the possibility of the user altering the bearing pre-load.
Perhaps they've just learned the lesson from HT-II that there is a lot of money to be made in bad bottom bracket design, I noticed that the old design BB-UN55 and BB-UN72 are hard to get hold of and there is a new cheaper BB-UN300 design?
Are you sure it's the BB and not the square taper that's clicking? If you take the chain off, hold the seat post and spin the crank, a failed BB will be detectable as a rumble though the seat post. A click on the other hand rather suggests that the square taper is working loose, which is an old problem and why you don't see them much these days.
Changing the BB won't affect the likely culprit, which is most likely the square taper
> Failing as in a loud click that can eventually be felt through the cranks (defo not pedals etc).
You say defo not pedals etc but clicks can be notoriously difficult to diagnose, it could be pedal, pedal/crank thread, crank/BB interface, saddle, seatpost, frame,... Also, click does not necessarily mean replace the bb, it depends on how bad it is.
I've got a cheap set of pedals used only for diagnosis of clicks
I always grease the spindle well before fitting the crank arms and I've checked they're still tight and the fitting is still square no rounding off.
> I've got a cheap set of pedals used only for diagnosis of clicks
> I always grease the spindle well before fitting the crank arms and I've checked they're still tight and the fitting is still square no rounding off.
That sounds like the problem then. You’re not supposed to grease the interface between the square taper axle and the crank arms. That allows them to go on too tight and typically deforms the square taper interface in the crank arm.
I’ve seen this done wrongly many times (I used to run a bike shop). The over tightening deforms the cranks, leading to more over tightening and so on. First you get clicks and eventually the crank can fall off.
The correct thing used to be that the axle and crank should be cleaned, fitted, tightened to 45nm, ridden for 50 miles or so, then re-torqued.
Modern splined designs are way better.
As afc says, no grease. Or, I was once told, nose grease only... Anyone what told that? I don't grease.
Yes, my old un72s from 2004 is still fine!
Agreed…I had to swap out the LH crank on my bike to stop the incessant creaking…
The creak followed the crank to the other bike I tested it on.
Might want to read the comments in the link I posted earlier.
> The creak followed the crank to the other bike I tested it on.
That's you knee clicking then
I'm still not convinced it's the axle/crankarm interface.
If it was 'too tight' and deformed the crank hole, why would the noise disappear with a new BB?
Reading what Artif linked to, they seem to agree about reforming the taper by tightening
If the BB is knackered you should still be able to feel the click and or roughness when you turn the axle by hand after its removed was this the case?
no need to grease the interface with a steel crank, but with alloy cranks on steel axle I always use a little bit of copaslip, then I'm able to get it off again when the time comes, without resorting to scaffolding poles on the extractor tool.
Interesting point. In a reply to a public comment in the reneherse article linked above Rene suggests;
"Also lightly grease the tapers to get a good seat of the cranks and prevent galvanic corrosion between (aluminum) crank and (steel) spindle…"
To the OP - Does the click always happen at the same point in the revolution of the crank? Loose crank arms tend to click on the power stroke after coming over top dead centre. ie circa 1-3pm on a clockface. I find that a worn BB tends to rumble all the way round upon rotation.
If the click is heard at the same point each time on each failed BB I would definited be thinking of alternative sources. Rene Herse suggest checking chainring bolts as a potential source of the click. If all the teeth are not straight on the chainring it could be catching on the cage of the front derailleur.
> I'm still not convinced it's the axle/crankarm interface.
> If it was 'too tight' and deformed the crank hole, why would the noise disappear with a new BB?
could be going loose over time which would also cause clicking/deform crank hole?... do you use a torque wrench?
Thanks all, ive checked all the things mentioned and am still at a loss.
Yes the click occurs in the same position (for now) which is as mentioned when the crank arm passes the 1 o clock position. From experience of the previous 2 BBs, this will deteriorate to a more sustained clicking / rumble.
Never mind, Ill go back to using HTII
> I'm still not convinced it's the axle/crankarm interface. If it was 'too tight' and deformed the crank hole, why would the noise disappear with a new BB?
I'd guess with a repetitively loaded greased square taper you'll gradually work the thin film of grease which remained after you torqued it down out of the interface loosening the fit.
jk
> I'm still not convinced it's the axle/crankarm interface.
> If it was 'too tight' and deformed the crank hole, why would the noise disappear with a new BB?
if you were to fit the new BB, with grease, then that might quieten things for a few miles. But the grease would move and the crank would start moving again (in relation the the axle) and your creaking would come back
btw, it was Madison UK (long time main importer of Shimano) who taught me not the grease the axle on square taper BBs.
You should clean and grade the threaded interface between the BB and the BB threads in the frame. Water can get down the seat tube from above. Regularly cleaning and regressing the seatpost and frame interface can help reduce water getting down to the BB shell.
> no need to grease the interface with a steel crank, but with alloy cranks on steel axle I always use a little bit of copaslip, then I'm able to get it off again when the time comes, without resorting to scaffolding poles on the extractor tool.
I used to find Copaslip was fine but just not necessary. I can’t remember a crank extractor tool not doing the job. Now getting a BB off a frame could be a challenge!
> I used to find Copaslip was fine but just not necessary. I can’t remember a crank extractor tool not doing the job.
I can, and stripping the thread, and using a pipe and lump hammer...
Did you use a torque wrench to install the cranks?
ive not used a torque wrench to fit any bike part, and ive built 11 in the last 20 years
> I'm still not convinced it's the axle/crankarm interface.
> If it was 'too tight' and deformed the crank hole, why would the noise disappear with a new BB?
>
Because you've taken the thing off and refitted it, and it will be seated well until it isn't and starts clicking again...
That's plausible, so would need new crank arms then
In-board BB cartridges tend to be rubbish.
If your bike will take outboard ones like Shimano Hollowtech II then consider changing your chainset and going for these instead. Most bikes that take a cartridge will take these.
I just went through cartridge after cartridge before moving to outboard bearings - they are much much better (for good reason). They are cheap, they last well, they ride well and they are cheap and easy to replace.
Cartridge bearings have to have the opposite bearings close together and in a small diameter race because everything is confined within the BB. Consequently the forces on them are high (because of the torque applied across the frame). The outboard bearings are much wider apart and can run in larger diameter races and the stresses are much lower. Coupled with that, the crank-shaft fixture is much better (making for a stiffer drive chain) and the whole lot weighs less.
Downside is the new crankset and a special spanner to fit them. I reckoned this was cost neutral after two cartridges or about 6 months and a significant upgrade to boot.
Aye thanks, I've got a ht2 crankset spare, i just thought square taper was meant to be longer lasting so tried that.
Never mind.
I've been told that one of the reasons why hollow tech BBs fail prematurely is because the BB shell faces aren't parallel and that getting the shell faced precisely will sort many issues.
I can believe this in the case of carbon frames with press fit BB shells or threaded shells that are fitted independently but, in the case of metal frames and carbon frames with a full metal bb shell insert the faces should really be square and parallel.
Bear in mind that Gravy is very much going against conventional wisdom. Decent cartridge square tapers will last tens of thousands of miles. None of the newer Shimano Bbs can be classed as decent.
Externals generally have exposed bearings, smaller balls and need the BB shell to be faced perfectly to allow perfect alinement. They tend to be more expensive if comparing like for like quality. Eg a basic SRAM GPX is somewhere qualitywise down there with a piece of Chinese junk that fetches maybe a third of its price. If you really want more info go and look at the CUK forum.
I've never had a problem with square taper BBs. I think I've replaced one in my life. They just work. My current bike has Hollowtech II. The bearings have been fine, but yesterday the left crank fell off without warning. No obvious reason why. I've never heard of that happening with a square taper crank.
I have! Happened to me about 2003 on the path from greenfield to Manchester, didn't have the right size hex key on my multi tool but just managed to tighten it enough to get home
As Gethin mentioned, if it *is* the bearings going and not the crank arm / interface *and* you've had issues in the past with HTII going quicker than expected, have you had the bottom bracket shell on your frame accurately faced? Less common that this causes issues on square taper, but it's still possible.
You could always get one of those expensive ones of that annoying guy on youtube - Search for Hambini.
I wrecked 10s of square taper cranks as a kid on various bikes, but it was always the crank interface and for years I had no idea you weren't meant to grease them. The only BBs I've had the bearing actually fail in are HTII... (oh, no, maybe I wore out the one on my city bike which gets zero maintenance and has been hammered for 17 years.)
I think I replaced it more than 10 years ago square taper, alu cranks. Regularly bunny hop up and down kerbs, winter, summer etc.
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