Press-Fit bearings with Ultra-Torque

[Berlinbybike]

There are more and more frames being offered with the bottom brackets suitable for press-fit bearings. With Ultra-Torque chainsets and cups the right bearing is held captive by a clip in the cup and the left held in place with a wavy washer. Probably not one of Campag's better ideas. How would the bearings be held captive in frames with press-fit bearings, given there's likely no place for the all important clip?

 

[accountantpete]

Hi BBB - the frames offered suitable for what you term "press-fit bearings" have just have the faces of the thread faced off so that the UT cups fit snuggly.

You need the UT BB cups including the clip in the right hand cup to hold the axle firmly and the wavy washer just adjusts for slight variations in the width of the BB shell on the frame.

 

[Berlinbybike]

The frames I was referring to have wider BBs and the bearings fit directly in the frame - no cups. This is the design which appears to not be compatible with Campag (?)

 

[accountantpete]

I haven't come across one of these frames - but would suspect that the Campy UT system wont work with them.

As you say the all important bit is the clip which effectively stops the bearing riding up the axle towards the crank - as the axle is slightly chamfered this would cause the bearing to seize.

 

[MartinC]

Campag make UT cups for the common press fit BB standards. You need to find out which BB shell you've got - that'll tell you which ones to get. Page down 'til you find them
http://www.chickencycles.co.uk/index.php?cat=7&sub=107&ord=2

 

[MartinC]

Sorry, read your question properly! The clip doesn't hold the bearing in. It holds the RH crank in during assembly prior to the cranks being bolted together. The bearings are a press fit in the cups.

 

[accountantpete]

Sorry, read your question properly! The clip doesn't hold the bearing in. It holds the RH crank in during assembly prior to the cranks being bolted together. The bearings are a press fit in the cups.

No - the clip is needed to stop the bearings moving slightly up the axle under heavy load.

I tried it without the clip and the left hand bearing soon moved and seized.

 

[Berlinbybike]

Without the clip the crankset could move laterally as much as the wavy washer would allow. I think it's a lousy design and obviously not well understood. It won't work with my new frame, apparently.

 

[MartinC]

Without the clip the crankset could move laterally as much as the wavy washer would allow. I think it's a lousy design and obviously not well understood. It won't work with my new frame, apparently.

That's exactly what the wavy washer is for - it sets the lateral preload on the bearing. On reflection Accountantpete is right - the clip stops the RH bearing outer race moving in the shell. From an engineering point of view it's a good design because it produces a very stiff and secure axle joint. But it relies on the BB shell width being in close limits so that the end float (set by the wavy washer) is right. Having a BB shell that's not faced properly (or leaving out the clip I guess) is bad news for a UT BB. I guess this (along with production costs) is why they've dropped it on the cheap end components - if you've got an expensive frame then it's probably been faced properly.