From square taper to outboard bearings - DISADVANTAGES?

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JohnW
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From square taper to outboard bearings - DISADVANTAGES?

Postby JohnW » 17 Aug 2014, 11:56pm

There is already a thread about the supposed advantages of hollowtech bottom brackets, over the traditional square taper ensembles. The advantages seem to be in theory but not in cost or, most importantly, long term serviceability. I include all outboard bearing types in this comment.

I've never used anything but square tapers so far, but from talking with cycling colleagues, and with two LBS proprietors it seems to me that the outboard bearing bottom brackets give a lot more trouble/problems and less mileage than the square taper BBs.

What is everyone's experience?

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Erudin
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby Erudin » 18 Aug 2014, 12:14am

1. Bottom bracket needs to be perfectly faced before installing.

2. Over tightening the cap when fitting left crank arm will side-load the bearings and cause premature wear.

3. In my experience the bearings will not survive short bouts of riding through fords/floodwater like square taper bb's do.

4. Bearing quality and sealing varies, I've had bearings fail after just two weeks of riding and others that are lasting years.

1 and 2 can be overcome with correct installation. 3 and 4 are the dealbreakers for many, I'm able to live with it as I've got a cheap supply of reliable bearings and the tools to easily fit them into the old cups.

tim-b
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby tim-b » 18 Aug 2014, 6:31am

Hi

Next time you're in the LBS, please ask which side of the OBB tends to fail first in their experience, drive-side or non-DS

Regards
tim-b
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JohnW
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby JohnW » 18 Aug 2014, 10:34am

tim-b wrote:Hi

Next time you're in the LBS, please ask which side of the OBB tends to fail first in their experience, drive-side or non-DS

Regards
tim-b


Never thought of that - I'll ask around. What's your experience?

bikerwaser
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby bikerwaser » 18 Aug 2014, 11:12am

both myself and a friend have had major problems with Shimano BB51's ( we've both averaged around 1000 mile out of each one ). He changed his to Shimano LX and I've change to HOPE . His LX has done more than double that of a BB51 and I'm now on about 4000 miles on my HOPE. my HOPE was 5 times the price though.
One main reason the BB51's don't last is probably that they're not stainless bearings. not sure why they'd put non stainless bearings in a BB when it's the main place that gets all the water and crud thrown right at it.

pete75
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby pete75 » 18 Aug 2014, 11:36am

bikerwaser wrote:both myself and a friend have had major problems with Shimano BB51's ( we've both averaged around 1000 mile out of each one ). He changed his to Shimano LX and I've change to HOPE . His LX has done more than double that of a BB51 and I'm now on about 4000 miles on my HOPE. my HOPE was 5 times the price though.
One main reason the BB51's don't last is probably that they're not stainless bearings. not sure why they'd put non stainless bearings in a BB when it's the main place that gets all the water and crud thrown right at it.


Once a ball race is full of crud, by which you presumably mean gritty matter from the road surface, it matters little what material the bearings are made of.
The more expensive BBs have better sealing to keep the bearings clean.

Brucey
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby Brucey » 18 Aug 2014, 11:49am

if there is even a small amount of water (especially salty water in winter) inside a bearing, and the corrosion-inhibiting additives in the grease (if there is much, which I doubt in microscopic amount of shimano bearing grease you find inside...) is exhausted, a non stainless bearing could be 'wearing' (actually more eroding I suppose) ten or a hundred times faster than a stainless steel one when in use.

In addition the non-stainless bearing will be merrily corroding when not in use, too. The latter explains the matching marks that you often get on both balls and ball races.

If a stainless steel bearing is contaminated with water its life will still be shortened, just not as much as a non-stainless bearing.

As noted above, not all 2RS bearings have the same seal design; some work a whole lot better than others. Unfortunately identifying which of the less expensive bearings is likely to have decent seals is not easy.

cheers
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pete75
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby pete75 » 18 Aug 2014, 12:12pm

Brucey wrote:if there is even a small amount of water (especially salty water in winter) inside a bearing, and the corrosion-inhibiting additives in the grease (if there is much, which I doubt in microscopic amount of shimano bearing grease you find inside...) is exhausted, a non stainless bearing could be 'wearing' (actually more eroding I suppose) ten or a hundred times faster than a stainless steel one when in use.

In addition the non-stainless bearing will be merrily corroding when not in use, too. The latter explains the matching marks that you often get on both balls and ball races.

If a stainless steel bearing is contaminated with water its life will still be shortened, just not as much as a non-stainless bearing.

As noted above, not all 2RS bearings have the same seal design; some work a whole lot better than others. Unfortunately identifying which of the less expensive bearings is likely to have decent seals is not easy.

cheers


Yes but they're no less immune to wear caused by grit which is what I understand then term "crud" to mean.

Brucey
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby Brucey » 18 Aug 2014, 3:28pm

re the crud, I agree. However -perhaps controversially- I suspect that the wear from the grit itself may often be the lesser part of what happens when the crud gets in to many bicycle bearings; it may be the water that gets in with the crud which does the real damage.

The reason I think this is that I've seen just a few bicycle bearings that were contaminated with crud that had no water in it and these bearings -although worn- were much less worn than I had expected them to be.

By contrast bearings with just water and grease in (to start with) can quickly look pretty terrible.

Maybe YMMV here; it certainly may in some other applications where speeds are higher etc.

cheers
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andrewjoseph
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby andrewjoseph » 18 Aug 2014, 4:14pm

I've had bb50 somethings start grinding after a few months winter mountain biking. This happened on two new bikes and three subsequent like for like replacement. Upgrading to more expensive bb50 somethings they lasted a few more months.

Changed to Shimano obb and they last a few years on my wife's bike, 18 months on my mtb.

The square taper on our road bikes are about 5 years old and show no signs or wear.
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willcee
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby willcee » 18 Aug 2014, 10:37pm

Been reading and i'll comment on which side is most found worn on HT2. ime its been the n/side. left..road bikes anyway, and one mtb i serviced last week had the left side shot.. on some definitely the cause is likely overtightened side thrust. as i have said before many up market LBS have a service practice of removing the chainset to clean the rings chain etc imo this disturbs the fragile bearing previous sweet tracking and perhaps causes a different ball track within the bearing case.. i have dismantled the bearings from the shells , they are very light and very small, i have somewhere the size and brg number for replacing same but haven't got around to it yet , anybody here tried this and what success..will

tim-b
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby tim-b » 19 Aug 2014, 6:41am

Hi
JohnW said
What's your experience?


Here's one http://forum.ctc.org.uk/viewtopic.php?f=5&t=85883 and on another make the NDS went first as well, so two, which isn't statistically significant in the grand scheme

I must point out that both of these OBBs were fitted to ready-built bikes and supplied without instructions. I didn't maintain them and in my ignorance I thought that a sealed bearing was just that. Sealed.
They had a pretty wet time, the second one was on my MTB and washed off with the garden hose :) Not good

They're cheap enough, I've just put an Ultegra OBB in the spares box for £12.50, and I will be maintaining them from now...

Regards
tim-b
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Brucey
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby Brucey » 19 Aug 2014, 7:07am

willcee wrote:Been reading and i'll comment on which side is most found worn on HT2. ime its been the n/side. left..road bikes anyway, and one mtb i serviced last week had the left side shot.. on some definitely the cause is likely overtightened side thrust....


the bearing preload on the left bearing is reacted by the right bearing, i.e. the preload is always the same both sides. Load-wise the RH bearing sees the chain tension load as well as the rider's pedalling force, so if everything were equal the RH bearing should wear first. Yet I agree that it is the LH bearing that wears first in most cases.

My view is that the reason for this is simple; the slightest splash of chain lube helps the seals on the RH side and there is just a tiny bit less crud that gets as far as the seals on the RH side; it ends up over the chainset instead. (in a crosswind, the crud from the front wheel can take a curved path and whilst the lee side stays bone dry, the windward side sees a shower of crud that comes in sideways; shields that don't overhang enough then let the crud in (on the left side) but on the right side it goes all over the chainset instead.)

cheers
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reohn2
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby reohn2 » 19 Aug 2014, 7:43am

Brucey wrote:My view is that the reason for this is simple; the slightest splash of chain lube helps the seals on the RH side and there is just a tiny bit less crud that gets as far as the seals on the RH side; it ends up over the chainset instead. (in a crosswind, the crud from the front wheel can take a curved path and whilst the lee side stays bone dry, the windward side sees a shower of crud that comes in sideways; shields that don't overhang enough then let the crud in (on the left side) but on the right side it goes all over the chainset instead.)

cheers


I'll buy that,and add that the spider/chainrings actually spins off the spray/crud combination.Which tends to be in sympathy with Bob's experience with his 'bent where,on another thread he mentions his c/set is out of the spray area out in front of the wheel(s).
All of which points a suspicious finger at inadequate weather proofing,providing the bearing preload is correct,etc.
Square Taper* have non of these issues of course but aren't as stiff I'm told :roll:


* sorry to mention the S/T words :mrgreen:
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NUKe
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Re: From square taper to outboard bearings - DISADVANTAGES?

Postby NUKe » 19 Aug 2014, 8:46am

Square taper or outboard bearings,both wear because they are expendable non serviceable parts.. Currently experimenting with campag bb bearings to see if forcing new grease through every 2k helps . Also using moly grease. Early days on this .
NUKe
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