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Discussion Starter · #1 ·
Hi guys.

I have a question about the possible origin of this. Yesterday I removed the Shimano Ultegra 6800 crankset for the first time since I bought this bike four months ago. This is the current state of the spindle. I cleaned it thoroughly using green scourer and degreaser. The central part of the spindle has some kind of abrasion and the area where the bearing is placed on the non-drive side is quite polished .
I have no idea what kind of maintenance the former owner used to perform. Thank God there are no creaks nor play yet but I'd like to stop this degradation before it's too late.
Any ideas of what has been causing this?

Thank you all.



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Discussion Starter · #3 ·
The bearing freezes and the spindle turns in the bearing. Is there a lip or any wear that you can feel with a fingernail?
Hi Tyler.
No, there's not noticeable lip between the bearing area and the rest of the spindle yet. I don't have a digital caliper either to check how much material was polished compared with the nominal 24mm diameter.
 

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It's corrosion. The spindle is made from steel, so just scrape the surface if it's impeding assembly, and lube it up. If it's covered in grease/oxygen can't get to it, it can't corrode.

Usually the bearing journals on the crank look wider--is the crank fit directly in contact with a bearing? Usually that style of bottom bracket is very poorly sealed.
 

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Responses above got it right.

One other thing though, 6800s are failing catastrophically at times. I have a set also. The drive side crank arm halves separate. Google it, see the failures, and then keep an eye on the problem areas. You should be able to see the failure starting to occur if you're one of the lucky ones. Catch it early and you won't risk a crash.
 

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Discussion Starter · #9 ·
I guess the solution is to apply a cover of grease all over the spindle and replace the bearings. The current ones are 37x24x7, so there's steel-steel interaction between the spindle and the inner race of the bearings. I'll pick the Trek original BB90 or the C-Bear or similar. They are 37x25x7 and they have a plastic seal that reduces the diameter. I guess the plastic tophat is a much more friendly set up for the spindle.

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Surprisingly, the Trek kit is rather high quality, with NSK bearings. It's usually the frame that is slightly out of spec, though a properly equipped shop that sells Trek can ream out your current frame "cups" and install new, properly sized ones.

If/when you swap bearings, you can press them in/out by hand, you'll need to investigate the above fix, anyway.
 
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