Noisy bottom bracket SHIMANO BB-RS500

Question

About a year ago I've got this Stevens Supreme fitted with Shimano Tiagra BB-RS500 bottom bracket.

In less than 2 months it started clicking and screeching loudly which only had gotten worse over time. Eventually I decided to get a replacement and to try something else, and installed Shimano Ultegra SM-BBR60 BB but unfortunately it had shown exactly the same problem, again in less than 2 months. I can get a replacement once more but I wonder if there is something wrong with the bike frame, or I have to do some maintenance to keep the bearings in good shape. So I see these options:

1. I am just unlucky and just have to replace it once more and hope it will be OK the next time.
2. There is something wrong with the bike's frame itself. I noticed that if I press pedals very hard it noticeably bends. So I may imagine that the bottom bracket does not like side forces. I am not sure what to do if this is the actual problem.
3. The noise comes from somewhere else. But it clearly synchronized with crank rotation, also after I have installed a replacement it did run smoothly for some weeks.
4. The bearings require some dedicated maintenance. But I could not find any instructions in this regard, and there is "do not disassemble" on the bearing's rim. So the best I could imagine is to use some liquid oil that can get in without taking the cartridge apart. I tried that but it helps only for 15 minutes of riding and only temporarily.
5. I read somewhere that these models of bottom brackets use small-ball bearings, maybe there are some compatible bearings that I could try and that are more reliable?
6. Maybe there is a way to restore the bearings?
7. Something else?

Did you have similar problem?

Answer 1

I agree with @Criggie regarding the comment that there is a high suspicion of misalignment of the bottom bracket cups (they are not perfectly parallel) when they are installed. This infers a misalignment in the frame or some flaw in the bore of the BB shell. If the cups are not parallel, there is uneven forces acting on the bearings causing premature wear and noise. The evidence for this is the very early noises produced by 2 different bottom brackets--ones that are typically high quality, long lasting models. If you uninstall the right crank to expose the spindle, you will notice the rings around the spindle where the bearings articulate. Look for inconsistencies in these tracts. This would also be evidence of a misalignment.

These Shimano Hollowtech2 bottom brackets are not serviceable. They can be cleaned externally and fresh grease applied on the inner aspects, the rings that touch the spindle as well as the spindle itself. Access to the bearings is not possible. Not easily and without a high probability of damage to the sealing system.

A well-equipped bike shop will have tools that check the parallelism of the bike's BB shell. They could "face" the ends of the shell--remove material--to make the ends parallel to each other and that will allow the cups to be parallel when installed. However if the bores of each side have center points that are not on the same line, that would be a problem that can't be solved (AFAIK).

Check, too, with Stevens and any warranty they may offer. The shop where you got the bike should be willing to help in that regard, including the testing of the shell for parallelism and/or bore misalignment.

Here is a link to the English PDF of the Stevens Bicycle User Manual. On page 93 you'll find the warranty details. The warranty is 2 years from date of purchase, so you should have ample time to work it out.