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While replacing chain this morning on my Boardman CX. I thought the BB had quite a lot of resistance. It was smooth though. I had this replaced for a ROTOR PF30 in november as I don't have the tools. Basically with no chain the chainset spins at best 1 turn with a flick of the finger. Shimano ones on my MTB in the same situation spin freely. With very little experience of these PF30 BB's, is this OK or does it require adjustment if it can be adjusted. Or have the bearings gone already. Its only done about 500km since being installed. LBS closed today.
If the bearings spin freely on your Shimano ones that means the seals are quite worn/on the way out.
New bearings should not spin too freely and if you can make it spin once with the flick of a finger that sounds fine.
Cheers that is a relief, Time saved now going to LBS and looking stupid.
The rubber seals on BB cartridge bearings create a bit of drag, preventing them from spinning freely - in time the seals wear a little which makes them spin a little better - it makes negligible difference to pedalling effort. Grab the end of the crank and push against the bike to check for any axial play / rocking to make sure they're adjusted correctly - any play or grittiness suggests they need attention. If you've been riding all winter, then 500km from a PF30 BB could be doing well.
A 'this is peaty' episodes from last year showed Greg Minnars mech putting 15000 revolutions on a saint BB with a cordless drill to get it running super free before installing it a world cup race bike.
But he gets a new one whenever he wants. Probably.