All Enduro bearings are products to the exact, industry specified, sizes. However, different frames and hub shells use different tolerances. Some can be slightly undersized while others are slightly oversized. To account for this, you must make sure that your bearings are seated completely and properly before riding. Often, in an undersized shell, the bearing can become cocked at a slight angle. Even when using the BRT-005 it can be hard to tell whether the bearing is fully seated or not. If you find the bearing feels rough after it has been pressed in, tap the bearing lightly with a plastic mallet in even intervals and then check it again. Often, this fixes the problem and the bearing seats fully allow it to spin freely.