Anybody know how often wheel and crank bearings need repacked?
I just had to replace the freehub body on my Ultegra rear hub because it was skipping under load. You have to remove the axle to change the freehub body, and when I opened up the hub after a couple of 5,000-mile years, the grease in it was still soft and clean and transparent yellow. The bearings themselves could have gone many times as long without maintenance. That depends heavily on having it adjusted correctly and having good dust seals though. Cup-and-cone bearings usually get adjusted much too tight. There should be some play in them that just barely goes away when the skewer is squeezed down. With good dust seals and the right adjustment and repacking every 20,000 miles, they will last your lifetime.
The old, repackable-style bottom brackets (crank bearings, as you call it) usually seemed to last 10,000 or 15,000 miles, maybe a little more or less, depending on how hard you ride and how much play you're willing to put up with. You should probably re-pack them every few thousand miles.
The sealed-bearing BBs with square-taper or billet spindles generally don't last that long. Our 135-pound son with 15,000 miles on one of his bikes with the Isis-type BB is already on his fourth one.
-bearing-type however lasts much longer than any of its predecessors, because putting the bearings outside the BB shell gives room for more and bigger ball bearings, and reduces the load from the side-to-side torque. The cranksets that have the spindle as an integral part of the right crank arm uses this kind of bearings. I have a Truvativ crank with the GXP BB with over 15,000 miles on it, and the bearings feel perfectly new. I should mention that contrary to popular belief, this type does not
widen the pedal stance at all. On my triple crankset, the bearings are farther out than the tiny chainring, almost in the plane of the middle ring. The chainrings still nearly touch the chainstay.
This message was edited by whittierider on 10-9-08 @ 1:33 PM