How much should a brand new Shimano HT2 bb spin when correctly preloaded?
I've fitted an XT HT2 bb with RF cranks so don't have the screw up preload option.
I've fitted enough rubber washers to allow the cranks to spin 1.5 to 2 revolutions from a spin with my fingers. Is this loose enough to stop the bearings wearing out in no time?
Try this method. Loosen pinch bolts. Tighten preload bolt to limp wristed finger tight. Tighten pinch bolts moderately. Check for play in the bb. Repeat loosening the pinch bolts when you readjust the preload. Keep going till the obvious play disappears. Once obvious play has disappeared, tighten the preload cap a further quarter turn.
This method means the final quarter turn will remove any tiny micro play you can't feel by hand. However it will mean you can only over tighten by no more than a quarter turn, which won't cause damage.
I've fitted an XT HT2 bb with RF cranks so don't have the screw up preload option.
no pinch bolts or preload collar I'm afraid, just add or remove rubber washers on the axle to Adjust preload. Just trying to get an idea on a 'spin test' to guestimate the correct preload
*must read posts fully*
Ahem
I'd try a variation of the idea, try too few washers and work up adding one at a time. The cranks will spin pretty slowly with a new bb.
Try it before you tighten up the crank fully, if it slows appreciably after you've then tightened it, you've got too much preload and a predictably short BB lifespan.
As little as possible, they are not angular contact bearings so do not really need any preload, just enough to stop the cranks moving from side to side within the bb