Author Topic: best square tapered BB?  (Read 3740 times)

best square tapered BB?
« on: 20 June, 2018, 10:12:09 pm »
I have had not much luck with Shimano's UN55 lately
2 clicked and creaked from new and the third has given up after 2600kms


Are there better options?

thanks

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
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Re: best square tapered BB?
« Reply #1 on: 20 June, 2018, 10:29:18 pm »
Do you commute under water?  ;D

That sounds like a serious alignment problem, not noted for frequent failure, something is going wrong somewhere.


VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Re: best square tapered BB?
« Reply #2 on: 20 June, 2018, 10:34:29 pm »
It's been a rainy season, has'nt it.

this one very suddenly gave up on a rainy 300, it goes round but makes a real grinding and clicking under load.


Re: best square tapered BB?
« Reply #4 on: 20 June, 2018, 10:49:19 pm »
How about Royce?

I bought a secondhand one years ago but still haven't used it yet.

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: best square tapered BB?
« Reply #5 on: 20 June, 2018, 10:50:23 pm »
When I install a replacement BB I always dry fit first without tools to be sure the threads are clean and free. Then with tools and plenty of grease. The grease isn't to lubricate the bearings, it's there as an attempt to keep the weather out. 'Sealed bearings' are maintenance free only as long as the moisture is kept out.

Another question that must be asked is are you installing both parts of the BB? Sorry, it's not that I'm doubting your mechanical abilities. 
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Samuel D

Re: best square tapered BB?
« Reply #6 on: 20 June, 2018, 11:09:14 pm »
The Shimano ones that I’ve seen, even the cheap ones, have lasted a long time. But consider this SKF model for extreme reliability, assumming it lives up to its hype and price.

Re: best square tapered BB?
« Reply #7 on: 20 June, 2018, 11:32:22 pm »
The old un54.. is currently on my winter bike..
And is working well since ahem 2010.
Might put it back in the Audax bike.

I'm hoping it's just a bad batch as my bike hasn't been dropped or crashed.
I grease with loads of anti seaze.. both caps in.

Re: best square tapered BB?
« Reply #8 on: 21 June, 2018, 12:06:28 am »
recently some UN series BB have been supplied with LH cups that are basically the wrong size. If they are just fitted the installation will very often fail in short order and it will often take out the RH threads in the frame.

So some care is needed when installing a new unit of this type. The problem is so bad that you can buy a cup that fits properly from a third party and folk buy them even though they are almost the same cost as a whole UN BB.... ::-)

If you want a UN BB to last really well then

a) make sure that the LH cup fits properly in addition to the usual fitting methods and

b) be sure that the tightening of the cups doesn't preload the bearings excessively; to gauge this take a used unit with some free play in the bearings and see how the free play varies with how the unit is fitted. It soon becomes apparent that you are better off relying on threadlock and not high torque to retain even BBs of this sort.

c) grind through the centre shell of the unit (very carefully *) and pack it full of grease.

(*) I use an angle grinder with a cutting disc in it for this job. When the wheel is just about to break through the remaining material is so thin that it will easily glow red-hot. At this point it is thin enough that you can punch through and if you are careful you won't get too much crud inside the unit. If you break through the wall with the grinder, there will be all sorts of grot inside the unit and much cleaning is required. Having packed the unit full of grease, you can bind tape around it before installing it in the frame. BBs that are so treated can last a decade or more easily; something that less often happens if you don't do this.

cheers



Re: best square tapered BB?
« Reply #9 on: 21 June, 2018, 08:00:49 am »
Thanks Brucey

Re point a. I'll insert the lh cup first to see if it fits before backing it out and inserting the BB.

I'm a bit lost on point b. Re how I can damage the bearings by overtightening the BB. The shell is self contained . I'll have a think and see if I can understand.

Point c . I'm not skilled enough to try this.!

But great info as always, thanks.

Having sleept on this problem.. I now wonder if the lack of a front mudguard is causing a fine mist around the BB and early failure.
(Mudguard no longer has clearance since I switched from 13mm to 17mm rims with 25c tyres)
I have had some rainy Audax this season.




Tim Hall

  • Victoria is my queen
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

Re: best square tapered BB?
« Reply #11 on: 21 June, 2018, 09:17:34 am »
I believe Campag BBs can be Italian or English thread. You definitely have a point on ISO vs JIS.

Re: best square tapered BB?
« Reply #12 on: 21 June, 2018, 09:49:57 am »
I believe Campag BBs can be Italian or English thread. You definitely have a point on ISO vs JIS.

Campag sqaure taper BBs can indeed be either Italian or English thread, but are all ISO. They also only come in certain spindle lengths - think 111mm or 115mm for Centaur and only 102mm for Chorus.

I've heard good reports of SKF square taper BBs, available in both JIS and ISO (and Italian and English threading), they're more expensive than Shimano BBs, but a little cheaper than Phil Wood (which is another high-ish end option) and much cheaper than Royce, though the latter are beautifully made. The only thing that slightly puts me off the SKF BBs a little is that the spindles are stainless steel, so possibly more brittle than chromoloy steel - see the text quoted from Compass Cycles below - though this may not be an issue in practice, at least for relatively light riders like me.

See: https://www.velovitality.co.uk/products/skf-bottom-bracket

"SKF bottom brackets are made entirely from stainless steel and aluminum – even the bearings – so they won’t rust or corrode. However, stainless steel is more brittle than Cromoly, so these bottom brackets only meet the “City/Trekking Bike” standards for fatigue resistance, and not the highest “Racing Bike” standards to which our other components are designed. This is the same for many other high-end bottom brackets, which also use stainless steel spindles, and SKF bottom brackets perform fine under most riders, including very strong ones. However, if you tend to break components, we suggest you look elsewhere for a bottom bracket." - https://www.compasscycle.com/shop/components/bottom-brackets/skf-bottom-bracket-jis-square-taper/

Old enough to know better, but young enough to do it anyway

Re: best square tapered BB?
« Reply #13 on: 21 June, 2018, 10:08:31 am »
Thanks Brucey

Re point a. I'll insert the lh cup first to see if it fits before backing it out and inserting the BB.

the fit problem is worst between the cup and the cartridge unit. Often there is a 0.5mm clearance between the parts before they are fitted.  The LH cup usually 'crushes down' on the cartridge unit but not always that much.

Quote
I'm a bit lost on point b. Re how I can damage the bearings by overtightening the BB. The shell is self contained . I'll have a think and see if I can understand.

BB threads are usually not perfect and not perfectly aligned either (check the cartridge for concentricity before the LH cup is installed). The LH cup bears against the cartridge unit with a mighty force; (with low friction in a 1mm pitch thread (eg an M6), a modest torque will easily generate an axial load of about one tonne; the installation loads on a BB unit are usually much more than this).

The result of all this is often (usually) that there are considerable (installation generated) loads on the bearings. Often you can feel that the spindle is mysteriously slightly bindy when the cartridge is installed, in contrast to how it felt beforehand. It isn't unusual for a unit that has noticeable free play to manifest none once it is installed.

The shimano design is considerably better than many other cartridge units in terms of isolating the bearings from installation-related  loads but it is not immune by any means.

Quote
Point c . I'm not skilled enough to try this.!

But great info as always, thanks.

I tried first on a well-used unit. It was nowhere near as difficult as I had first imagined. If you don't fancy this route you can pick the LH seal  out of the end of the unit instead, but this risks seal damage.

Quote
Having sleept on this problem.. I now wonder if the lack of a front mudguard is causing a fine mist around the BB and early failure.
(Mudguard no longer has clearance since I switched from 13mm to 17mm rims with 25c tyres)
I have had some rainy Audax this season.

no contact seal can be expected to work without a film of lubricant between the seal lip and the shaft. If you look inside a new unit it is pretty obvious that they have been so parsimonious with the grease that it won't take much road spray to overwhelm the grease. What is less obvious is that the grease they use is 'not at all resistant' to salt water. This means that winter use without mudguards will indeed be likely to cause premature failure due to water ingress.

So there are three main reasons why a unit might start making noises early on;

1) that the parts never fitted properly and the cartridge is moving about (which usually risks that the BB threads will be damaged)
2) that the (installation generated) preload on the bearings is excessive and the bearings are starting to fail
3) that the seals have failed and water has entered the unit.

Looking at the SKF unit, this is manufactured with seals that are not that much better than the shimano unit, and the thing is filled brim full with lubricant (a gear oil I think) so that it can have a long service life. I don't know whether the design confers an immunity from installation-generated bearing preload, but I doubt it.

 The seals don't have to be that great to retain a goodly fill of SFG, (although there may be some weeping in service) and SFG is mobile enough to re-wet the seals etc, so that is what I suggest you use inside units of this type. The SFG that is used in land-rover front swivels has loads of EP additives, anti-corrosion additives etc so that is what I suggest you use.

It may seem like a trivial point, but if you fill a BB unit with lubricant, you will have x10 or x20 the amount of lubricant present. If the lubricant is also mobile (oil or SFG) this means that any wear debris (or contaminant) is diluted by x10 or x20 as much. By contrast with a small amount only of grease present, and/or sticky (non-mobile) grease, the lubricant in the bearings is soon  loaded up with wear debris and contaminant, so that wear rates are much higher than you might expect; once wear starts it is like an avalanche towards failure; debris only ever begats more debris, and you are soon on a slippery slope.

Occasionally UN series BB units seem to lead a charmed life; it is my view that this occurs when the unit has somehow managed to avoid large installation-related loads, and something (cleaning regime or use of mudguards, say) has managed to keep the seal lips wetted, and has deterred the ingress of crud past the seals.

cheers

Re: best square tapered BB?
« Reply #14 on: 21 June, 2018, 02:39:01 pm »
I have a Stronglight JP400, purchased because the correct size UN55 that was there before wasn't in stock.  So far the Stronglight has outlasted the Shimano by at least 30%, though it's a sample of one.
https://www.spacycles.co.uk/m2b0s110p140/STRONGLIGHT-JP400-Aluminium

rogerzilla

  • When n+1 gets out of hand
Re: best square tapered BB?
« Reply #15 on: 22 June, 2018, 06:43:28 am »
Tange ones are interchangeable with Shimano (JIS), good quality, and available down to 103mm, useful for fixie conversions.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: best square tapered BB?
« Reply #16 on: 22 June, 2018, 09:12:31 am »

AIUI Campag taper isn't compatible with Shimano chainsets (ISO vs JIS).
International Standards OrganizationJapanese International Standard
Basically ISO Square taper for Campag, JIS for Shimano and I'm not sure about others.

zigzag

  • unfuckwithable
Re: best square tapered BB?
« Reply #17 on: 22 June, 2018, 09:14:55 am »
my un55(?) bb is the only part that i use since i've started cycling, and been transferred from one bike to another a few times. i reckon it has more than 50k km of use and just gets better with age with zero attention and tlc. it is so smooth now (without any play), that the cranks swing back and forth after stopping when spun without a chain - ceramic bearings have more friction than this!
maybe yours was from a bad batch or perhaps installed with the left cup overtightened?..

Blodwyn Pig

  • what a nice chap
Re: best square tapered BB?
« Reply #18 on: 23 June, 2018, 08:03:50 am »
I've always placed either O rings, or an off cut of a narrow tube, on to the  BB spindle, reasonably close fitting one, and smeared with grease, prior to fitting crank arms. These then are 'almost' squashed up against the shell, but add an extra barrier to the moisture. Done this for over 25 years, started in early 90's when I bought one of those new fangled MTB things, you know, before they were popular.

Re: best square tapered BB?
« Reply #19 on: 23 June, 2018, 12:13:58 pm »
that is not a bad idea provided it doesn't push too hard against any seals there might be, which may well cause them not to work so well.

FWIW I've had good luck with using offcuts of hose meant for cooling systems on cars. Heater hoses are often about the right diameter to slip over a BB spindle.

BITD Chris Juden recommended adding a length of radiator hose between the cups of 3-piece BBs; this would (if the BB shell and hose were drilled in the right place) allow the bearings to be regreased in situ.

cheers

Re: best square tapered BB?
« Reply #20 on: 06 July, 2018, 09:02:58 pm »
For Phil Wood BBs you can get "Mud Guards" - I wonder how much these actually help in practice to keep water and muck out of the bearings:

http://www.philwood.com/products/bbpages/midcupguards.php

Old enough to know better, but young enough to do it anyway

Gattopardo

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Re: best square tapered BB?
« Reply #21 on: 07 July, 2018, 10:05:28 pm »
Have had issues with a un26 bb, that the end cup tightens up the bb bearings so the bb becomes stiff.

Ended up getting a first branded bb from spa cycles.  No such problems, even with the replacement metal cup from the bb un26.