Cartridge bearing is rough when pressed in, but fine when taken out

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Manc33
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Joined: 25 Apr 2015, 9:37pm

Cartridge bearing is rough when pressed in, but fine when taken out

Post by Manc33 »

On a Hollowtech II bottom bracket cup, I have got a ceramic cartridge bearing that when out of the BB cup, with no grease in it and no seal on it, spins really smooth with hardly any friction.

When it's pressed into the bottom bracket bearing cup, without seals on to rule out any friction from the seals, it gets a lot of friction on it and feels lumpy when turning it. There's a big difference between when it's in the cup and out of it.

It's almost like the BB cup is deformed and yet it can easily be screwed in and out of a BB shell by hand, also I measured the threads with a vernier caliper (that goes to 0.1mm) and it's circular - the measurement doesn't change at all. I checked inside too and got no change in the diameter. It seems perfectly circular to me. Also circular is the inside ring of the bearing, at 23.9mm all the way around. I can't understand how this is happening.

What I haven't tried is turning the cartridge around, or trying it in the other cup, but I have a feeling if I take the (currently smooth) one from the other cup, that smooth one will suddenly become rough/lumpy when put in the other side, with the one that was lumpy swapped over, becoming smooth.

Another odd thing is it's not like it needs the force of a gorilla to press this cartridge in, so it's not like the BB cup is crushing it.

Maybe the inner bearing ring is whats deformed, so when it's out of the BB cup it's slightly oval but when pressed in, the BB cup forces it to try to be circular and it can't be, so it becomes rough? If the crank had a nasty whack I suppose that might make sense.
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tim-b
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Joined: 10 Oct 2009, 8:20am

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by tim-b »

Hi
Check that it's seated squarely.
I don't know what you have, however, a good quality steel bearing might be smoother when fitted than a poor quality ceramic version
Regards
tim-b
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Spinners
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Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Spinners »

I have a build going on at the moment on which I really wanted to use a square taper cartridge bottom bracket that spins freely but goes 'solid' when inserted into the frame (with much grunting, swearing and sweating). Honestly, you can't turn the spindle by hand.

I've had to switch to outboard bearings (BB-RS500) which screwed in much easier and it all seems fine.

:?:
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Brucey
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Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Brucey »

all the above issues are explained by variations in preload and damage.

There isn't a 100% perfect method for manufacturing and mounting cartridge bearings in bicycles; the bearing itself needs to be manufactured so that it has a defined 'fit' into the housing, such that it isn't going to be too loose or too tight. This deforms the outer part of the bearing, which causes the clearance/preload within it to change. There is often a similar issue with the inner part of cartridge bearings too. [The tolerances are tiny; often less than ten microns, beyond what can be reliably measured using any hand tools. At best you might be able to compare an old bearing's OD with a new one (provided both are round), and be reasonably sure it is within 10um or so.]

To specify the correct bearing (which can be made to any tolerance) you would need to know the tolerance of the housing, the tolerance of the shaft, and understand how stiff these parts are and therefore how the bearing will deform when it is installed. The reality is that these things might be attended to in new parts, but when they are replaced, none of these things are known or understood. Beside this some of the parts may be worn, so the installation will never be acceptable.

If you install a cartridge bearing and 'it feels rough' then you have some combination of

a) wear or damage in the bearing and
b) increased preload in the bearing

Often the latter goes unnoticed because the bearing is 'nice and smooth' by virtue of the way it is made. The slightest damage to the bearing surfaces and the same bearing will feel as rough as anything. The OP's rough bearing is almost certainly rough because there is too much preload; although ceramic balls are used the raceways are steel and this steel is not going to be 100% resistant to corrosion or wear. [BTW if you thing this makes it sound like I think 'ceramic bearings' are a rip-off/waste of time, you'd be right.]

'Sealed' ST bottom bracket units vary but none are 100% immune from installation loads. These can vary from 'small' to 'catastrophic' and the quality of the BB threads/facing is often paramount.

It is very easy to just bosh new cartridge bearings into something, but it is actually incredibly difficult to be sure that the installation doesn't have excessive preload I still prefer cup and cone bearings for most hubs.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
mercalia
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Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by mercalia »

I bought a square taper bearing like that a few years ago. Could be just sample variation and earlier ones I have are ok
CXRAndy
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Joined: 18 Aug 2019, 1:45pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by CXRAndy »

Check out Hambini on YouTube. He is an engineer, quite anal about tolerances of bike frames and bearings. He is quite outspoken about most aspects, but does talk sense. He manufactures his own Bottom bracket systems and helps clients with problems. He has slated quite a few high end frame makers and wheel manufacturers for their [inappropriate word removed] tolerances of their equipment.

Entertainment it is
Manc33
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Joined: 25 Apr 2015, 9:37pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Manc33 »

The BB is Hope with it's own Hope ceramic bearing in. Another problem is if you knock the bearings out of this, you're having to whack the center to do it, which is all very well if you're not planning on putting them back in again but you can't get at the outer ring to remove them, only to press them.
We'll always be together, together on electric bikes.
tooley92
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Joined: 22 Jun 2007, 9:49am
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Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by tooley92 »

Manc33 wrote:The BB is Hope with it's own Hope ceramic bearing in. Another problem is if you knock the bearings out of this, you're having to whack the center to do it, which is all very well if you're not planning on putting them back in again but you can't get at the outer ring to remove them, only to press them.


Are you using the proper Hope bearing tool to press out and back in the bearings?
Remember folks 'A pessimist is just an optimist with experience!'
Manc33
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Joined: 25 Apr 2015, 9:37pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Manc33 »

tooley92 wrote:
Manc33 wrote:The BB is Hope with it's own Hope ceramic bearing in. Another problem is if you knock the bearings out of this, you're having to whack the center to do it, which is all very well if you're not planning on putting them back in again but you can't get at the outer ring to remove them, only to press them.


Are you using the proper Hope bearing tool to press out and back in the bearings?


Nah I was using a stack of 37mm penny washers and a DIY rod thing I made. I managed to press it in so its slightly better than it was. I'm going to grab some normal steel bearings since they are dirt cheap and with the money not spent on hybrid ceramic replacements, I'll get hold of a proper bearing press.

An engineer said with those hybrid ceramics, the balls are made of a hard material, but the bearing races are still steel, so the balls wear a groove in the steel and yet on all steel bearings, that wear doesn't happen because it's the same material rolling against itself.

I had a think about it and thought yeah that's true, it's going to wear less if both materials are the same as each other, even if they are really cheap £2.50 jobbies.

Hybrid ceramic schmybrid scheramic!

If you had full ceramic it would work OK with both surfaces the same material again.

I managed to find them in China for about £32 for a pair - full ceramic.

24mm x 37mm x 7mm (MR3724-2RS)

Image

That's possibly the nicest bike part I have ever seen... I really need to get out more. :lol:
We'll always be together, together on electric bikes.
tim-b
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Joined: 10 Oct 2009, 8:20am

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by tim-b »

Hi
I've found Hope to be very helpful with their products, contact them
Regards
tim-b
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CXRAndy
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Joined: 18 Aug 2019, 1:45pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by CXRAndy »

The Watt saving using ceramic is extremely minimal. Ceramic are used for high speed applications, where dirt, water and grime are not really part of the equation. Adding the dust seal to the outside creates more drag than saved. Ceramic wear quickly once subjected to contaminants.

Check out Hambini on Youtube for his analysis of ceramic bearings and the costs. He suggests a good quality steel bearing is far better for cycles
Manc33
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Joined: 25 Apr 2015, 9:37pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Manc33 »

CXRAndy wrote:The Watt saving using ceramic is extremely minimal. Ceramic are used for high speed applications, where dirt, water and grime are not really part of the equation. Adding the dust seal to the outside creates more drag than saved. Ceramic wear quickly once subjected to contaminants.

Check out Hambini on Youtube for his analysis of ceramic bearings and the costs. He suggests a good quality steel bearing is far better for cycles


I have been watching Hambini vids lol

Yes there's no point to either the hybrid or full ceramics and the "cheap" full ceramics like ones from China actually have more drag to them than just about any branded steel bearing, that's far cheaper. This is a weird bearing size though and it seems like it has to be an Enduro, but they aren't expensive. In his tests the NTN bearings came out best (and aren't expensive) but they aren't made in this size.
We'll always be together, together on electric bikes.
tooley92
Posts: 1440
Joined: 22 Jun 2007, 9:49am
Location: West Yorkshire

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by tooley92 »

Manc33 wrote:
tooley92 wrote:
Manc33 wrote:The BB is Hope with it's own Hope ceramic bearing in. Another problem is if you knock the bearings out of this, you're having to whack the center to do it, which is all very well if you're not planning on putting them back in again but you can't get at the outer ring to remove them, only to press them.


Are you using the proper Hope bearing tool to press out and back in the bearings?


Nah I was using a stack of 37mm penny washers and a DIY rod thing I made. I managed to press it in so its slightly better than it was. I'm going to grab some normal steel bearings since they are dirt cheap and with the money not spent on hybrid ceramic replacements, I'll get hold of a proper bearing press.

An engineer said with those hybrid ceramics, the balls are made of a hard material, but the bearing races are still steel, so the balls wear a groove in the steel and yet on all steel bearings, that wear doesn't happen because it's the same material rolling against itself.

I had a think about it and thought yeah that's true, it's going to wear less if both materials are the same as each other, even if they are really cheap £2.50 jobbies.

Hybrid ceramic schmybrid scheramic!

If you had full ceramic it would work OK with both surfaces the same material again.

I managed to find them in China for about £32 for a pair - full ceramic.

24mm x 37mm x 7mm (MR3724-2RS)

Image

That's possibly the nicest bike part I have ever seen... I really need to get out more. :lol:


I’ve never bothered with the ceramic bearings in mine, always use Blue Seal bearings from eBay - seem cheap enough.

I do have the proper Hope tool to press out and in the bearings and it does a great job and doesn’t damage the bearings - like most Hope stuff it’s expensive but should last a lifetime.
Remember folks 'A pessimist is just an optimist with experience!'
Manc33
Posts: 2218
Joined: 25 Apr 2015, 9:37pm

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by Manc33 »

In a Hope BB, I can't see any way to get the bearing out without pulling on the center ring and the extractor tool is designed to pull on that inner ring.

On the hubs I think the outer ring is accessible, so you could press them out using the full diameter, but I'm not sure.

If you're removing them though you're probably pressing new ones in anyway.
We'll always be together, together on electric bikes.
tooley92
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Joined: 22 Jun 2007, 9:49am
Location: West Yorkshire

Re: Cartridge bearing is rough when pressed in, but fine when taken out

Post by tooley92 »

I think the hard bit without the correct tool is supporting the cup squarely whilst you drive out the bearing
Remember folks 'A pessimist is just an optimist with experience!'
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