Originally Posted by
mphemmens
Hello all, first post here.
Can anybody give me a definitive answer to this question?
I replaced the plastic pedals on my MTB a while back with new metal pedals, and they didn't seem to spin freely - I didn't feel any "drag" or anything like that, and they turned smoothly, but the pedal would only spin two or three times before coming to a halt. I wasn't sure whether this was normal or not so I stripped and re-greased them with some plain white lithium grease from Weldtite, but this did not change anything. If I loosen the cone I can get the pedal to spin for much longer, but of course the pedal then feels loose on the axle, and there is a risk that the bearings could fall out. Am I doing something wrong, or are the pedals just meant to be like that?
NOTE: In each bearing race there are 13 ball bearings; when the bearings are installed they do not form a complete circle, there is a small gap, but this gap is not big enough to accomodate an extra bearing. Is that normal?
Any help you guys could offer on this would be greatly appreciated!
Your pedals are 100% normal, and that's the way they should work. Measuring bearing drag by how many trins a pedal or any other item makes before coasting to a stop is an excercise in (how can I say this politely?) stupidity?, mechanical ignorance? futility?.
The drag measured by the spin test depends not only on the bearing drag, but on the viscous drag of the lubricant. the same unloaded bearing will spin much better with a light oil vs. a grease, so that's one reason the test is useless.
The more important reason the test is useless is it measures rotational inertia as well as, if not more than bearing drag. If you take any hub and spin it it'll turn a few times before coasting. Change nothing, but build it into a wheel and it'll spin at least twice as long because of the add rotational inertia of the rim. Want it to spin even longer? Attach lead weights to the rim and it'll amaze you how much better the bearing becomes. (not).
Pedals will never spin as free as wheels, because of the low inertia, add the grease and seal drag and some will be good if they make 1 revolution before they stop.
The only meaning test of pedal bearings is how they work when loaded. You'll feel a bad bearing through your foot, and a really bad bearing will cause the pedal to unscrew.
Stop obsessing about stuff that doesn't matter, and go out and ride the bike.