BB bearing grinding and new bearing grinding when replaced.

wilhol

Hi All,

I recently build up a winter bike and installed a Rotor BB386EVO to 24mm Bottom Bracket, the pressfit type with aluminium cups. Approx 600miles in and it developed a noise on the downward stroke of the NDS crank. When i took the cranks off, the NDS bearing was very notchy/grindy. I got a quality new bearing, was smooth out of the packet. I had it pressed in by the LBS, when installed it was better than the old one, but not smooth. Then having ridden it, noise is still there.

Any ideas what may be causing this? My only thoughts are that the cup is slightly deformed and therefore deforming the bearing when pressed in?

p.s, I know, I hate pressfit too.

TIA!

Ben6899

wilhol said:

Hi All,

I recently build up a winter bike and installed a Rotor BB386EVO to 24mm Bottom Bracket, the pressfit type with aluminium cups. Approx 600miles in and it developed a noise on the downward stroke of the NDS crank. When i took the cranks off, the NDS bearing was very notchy/grindy. I got a quality new bearing, was smooth out of the packet. I had it pressed in by the LBS, when installed it was better than the old one, but not smooth. Then having ridden it, noise is still there.

Any ideas what may be causing this? My only thoughts are that the cup is slightly deformed and therefore deforming the bearing when pressed in?

p.s, I know, I hate pressfit too.

TIA!

Or the BB shell on the bike is out of tolerance

edward.s

If you can tolerate his presentation style, Hambini on youtube will give you the full rundown on how things might go wrong.

As Ben says above, it could be the shell out of tolerance in any number of ways e.g. in alignment with the other side, in roundness etc

Time to break out the calipers :-)

wilhol

Thanks both! Seems like the shell could have been out of alignment or tolerance, which has caused the cups to deform, which ruined the other bearing and then the new one when it was pressed in. Although I’d be surprised if the cups could deform, they were a pain to get in though! A few things that could be the problem. Which makes it harder to work out a solution.

Ben6899

This one?

Pressed into a non-round shell, I'd say those cups would deform quite readily. How did the BB installation go when you built the bike?

david37

Never watch Hambini, it will play with your mind and youll think your bike is going to collapse He's very good.

joking apart bearings shouldn't feel notchy if everything on the frame is largely aligned. Bearings always seem to feel different in the shell to when theyre out. Since your bearing feels notchy at the point youve installed it I would ask wether the bearing you installed was actually as good quality as you thought. I would wonder if maybe it wasnt pressed in straight or maybe the BB cups are incorrectly installed.

wilhol

Thats the one Ben, they're aluminium so I thought they'd hold their shape, but evidently maybe not. They were fairly tough to get in!

It was after I went up a punchy climb that it started making the noise, so potentially it was at that point the cups may have deformed to the shape of the shell just enough to crush the bearing.

Good point Davit, I have lost all hope of ever having a quiet drive train after watching his videos! I think because the bearing which came in the rotor BB failed, and then this new one, it wasnt a quality issue, its a supplier I always use and have never had any problems.

I'll have to knock the cups out and try some measuring. But if the shell is out of shape, not sure much can be done.

masjer

Correct size bearings will never deform/crush being pressed into an aluminium cup. The steel they are made from is exceptionally strong. The bearing could have been damaged if pressed in using the inner race and not the outer.
Take the chain off the crank and check if the BB bearings are smooth. If not remove the crankset and feel (by hand) the bearings for smoothness.
Is the crankset installed correctly? Putting too much preload on the BB bearings can cause binding and rapid wear.

Ben6899

A bearing will bind, if it's forced into a hole that's out of tolerance for that particular bearing.

dennisn

I'm starting to think that the OP did not install things correctly. Also sounds like he didn't use the proper tool. I vote mechanic error.

webboo

Always positive eh, Dennis. However I vote English error it’s mechanical error.

dennisn

webboo said:

Always positive eh, Dennis. However I vote English error it’s mechanical error.

I don't think it's mechanical error. I think it's THE mechanic's error.

dennisn

For the record I have used threaded bottom bracket bikes and bearings all my life. Did my own maintenance too. Maybe once or twice in the past the BB came loose or needed adjustment. But nothing like volume of problems I read about here.

brian.paneurope7I7wolqz

Ben6899 said:

A bearing will bind, if it's forced into a hole that's out of tolerance for that particular bearing.

This is most likely. I replaced the bearings on my wife's aluminium Cannondale. I made the press myself on the lathe and got a shock when it became clear the hole was very slightly oval. The bearings were slightly gritty from binding the moment they went it after a struggle. It was only an aluminium winter bike but annoying. I can only think that the welding process distorted the bearing housing slightly. The old bearings ran free when I removed them, do there was nothing really wrong with them.

Hambini is pretty good and has called out some pretty shoddy work. Overall though I think he ruins his credibility with his over the top personal attacks and language. His fanboy folloWing is also pretty irritating.

I'm also nervous of anyone who thinks they are the best and infallible.

I'm another one for threaded bottom brackets. It's much harder for the manufacturer to get them wrong and they are more tolerant of error.

Ben6899

dennisn said:

For the record I have used threaded bottom bracket bikes and bearings all my life. Did my own maintenance too. Maybe once or twice in the past the BB came loose or needed adjustment. But nothing like volume of problems I read about here.

OP's BB is pressfit.

webboo

I’m sure Dennis will be along to say only a bad mechanic would choose a press fit BB.

masjer

I just had a quick look at Hambini's article on BB tolerances -I gave up after he was demonstrating how to remove a stuck BB from a carbon frame using a hairdrier to expand the carbon fibre frame and compressed air to cool (shrink) the alloy cup.
Carbon fibre doesn't expand with heat and the low pressure from the air line wouldn't cool enough either- I lost faith!

david37

To date i have never personally had a problem with pressfit bottom brackets. Perhaps I've been lucky. I've always built the frames myself and in the last few years ive moved to using the wheels BB. Easy to install, easy to replace bearings every couple of years.

I thoroughly clean the bearing interfaces and press in accordingly. I did have a BB30 frame at one point that was ridiculously easy to press the bearing in so i cleaned it and the bearing outside edge again and applied a little retaining compound and it was perfect.

I suspect that there are frames out of tolerrance out there but also a LOT of shop and home mechanics who just dont do it right. In this instance Cleanliness is next to godliness.

dennisn

webboo said:

I’m sure Dennis will be along to say only a bad mechanic would choose a press fit BB.

Give me one good reason to buy press fit on my next frame. Other than the fact that I may have to due to it being all that's available.

webboo

I didn’t say there is a good reason to buy one but as you have pointed out sometimes that’s all that’s available. Just like if I buy a bike in a couple of years time I suspect the choice will be disc brakes or disc brakes.

david37

dennisn said:

webboo said:

I’m sure Dennis will be along to say only a bad mechanic would choose a press fit BB.

Give me one good reason to buy press fit on my next frame. Other than the fact that I may have to due to it being all that's available.

1, access to groupsets and cranks that dont use 24mm Axle.
2, weight
3 errrr all those expensive tools will go to waste.
4 there arent any really.

Sloppy manufacturing may still lead to issues in CF frames that cant easily be repaired such as

1 installed incorrectly, one side forward of the other, or one side higher
2, if the bonding fails the frame cant be repaired at your LBS and is effectively a write off. on the plus side small frame repairers and builders may spring up and that sounds great.

Bike industry mass manufacturing isnt renowned for its QA.

dennisn

david37 said:

dennisn said:

webboo said:

I’m sure Dennis will be along to say only a bad mechanic would choose a press fit BB.

Give me one good reason to buy press fit on my next frame. Other than the fact that I may have to due to it being all that's available.

1, access to groupsets and cranks that dont use 24mm Axle.
2, weight
3 errrr all those expensive tools will go to waste.
4 there arent any really.

Sloppy manufacturing may still lead to issues in CF frames that cant easily be repaired such as

1 installed incorrectly, one side forward of the other, or one side higher
2, if the bonding fails the frame cant be repaired at your LBS and is effectively a write off. on the plus side small frame repairers and builders may spring up and that sounds great.

Bike industry mass manufacturing isnt renowned for its QA.

So, other than the bike industry wanting to sell something new and people wanting to buy it because it's new, why has everyone seemingly bought into press fit? Or did I just answer my own question?