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I received this email last week and I felt compelled to share most of it...
Dear Rogue Mechanic,
...My intent was to build the Colnago CX-1 myself with Campy Super Record components as I couldn’t allow having Japanese parts installed into the Italian frame. I’ve been a cyclist for over 40 years and 30 of them were with Campy components, and the last 10 with the Dura Ace.
As I started shopping around on the internet for comments / reviews and prices for the 2014 Super Record group, I stumbled upon the issue of the knocking noises for the Ultra Torque Bottom Bracket. I was surprised that Campy, after their long history of really making well made road bike parts, has issues.
I'm a mechanical engineer with 40 years experience as a machine designer of heavy newspaper printing press equipment. When I looked at and studied the assembly of the bottom bracket, crank and that wavy washer, I saw right away what was wrong and why the knocking noises exist. The culprit is the wavy washer. It’s a cheap way for Campy to allow that assembly to “work properly”because of the dimensional variations of different bottom bracket widths and the crank parts supplied by Campy. Working properly during assembly does not mean it’s working right for the forces created of turning the crank while cycling. The turning forces or torque applied to the crank is not uniform all the way around as all cyclists know and as we all try to achieve uniformity there. These non uniform torques will develop axial forces that squeeze of the wavy washer in and out. Axial movement of the crank will now exist and cause wear and then finally noises will happen. This axial movement of the crank must be constrained rigidly so as to not allow this wear. As an analogy, in printing presses, any axial movement of more than 0.003" at the printing cylinders will cause the print to be blurry.
Because the crank is held and located by the bearings, they need to be constrained rigidly.
So, ROGUE MECHANIC, your idea of the shims to account for dimensional variations and creating axial rigidity is the correct and perfect solution to remove any axial displacement.
It is how it’s done for preloading the Timken bearings in heavy printing presses running at paper speeds at 3000 feet per minute. ... using shims to preload and constrain the bearings.
I’m happy that I ran across your website and applaud you for your insight and your expertise in machining those shims. I bought two sets as I'm going to build another bike.
I did not and will not install the wavy washer.
The Colnago is built now and after 500 miles the crank turns as smooth as silk with no axial play and no knocking noises.
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