I have a Privateer 161 mountain bike. Ever since I bought it, most suspension pivot bearings run roughly when pressed into the frame. After the first 3 months I had the bike, I removed some of the bearings to inspect and found that the bearings ran fine when not in the frame.
2 years later, I found that the main lower pivot bearings were completely seized and would not rotate. I removed some of the bearing seals carefully, while the bearings were still in the frame, and found that there was no grease in the bearing whatsoever. After some coaxing and spraying a lot of wd40 in them and re-greasing, I still couldn't get them to budge. So, I bought a new bearing kit and some bearing extractors and bearing presses with appropriate drifts.
These lower main pivot bearings were extremely difficult to remove and the new bearings were also difficult to press in, even after cooling in the freezer. Upon removal, I did some measuring of the housing on both drive and non-drive side and also of the old bearing and new bearing.
Housing Non-Drive Side:
Housing Drive Side:
So, I know that bearings are often interference fit and in this case, we have a few things:
- Interference fit of old bearing - 32.02mm - 31.85mm = 0.17mm = 170 microns/micrometers
- Interference fit of new bearing - 32.01mm - 31.85mm = 0.16mm = 160 microns/micrometers
My question is this: Is this fit within industry standard for tolerances, or is it too tight of an interference?
I just can't imagine that the bearings should run so roughly when in the frame or be so difficult to install/remove with appropriate presses/bearing extractors. I've contacted Privateer and they tell me this is within tolerance, but after some research I am getting conflicting information. Also, they never told me what the tolerances were, just that it is within tolerance.