Numpty question – can I replace a knackered RF bb with any 68/73 bb? (to run race face evolve cranks)

eg shimano or hope?

Square taper? ISIS? External?

cranks are isis

24mm axle external = yes. XTR @ CRC = £25

ISIS = Yes. SKF are considered the Holy Grail of ISIS but sourcing one could be tricky.

Quick check before the rubber hammer comes out at lunchtime….

Got the XTR bb and the axle doesn’t go in anywhere near as easily as it came out…measured the inner race to inner race diameter and to my eyes it’s 23.5mm. Is that wrong or do I just get on with the “cradley screwdriver”

cranks are isis

I may have the wrong end of the stick here, but Shimano didn’t make ISIS stuff.

If

it’s 23.5mm

, it sounds like an external BB to me, if so, persuade it with a rubber hammer.

probably my confusion as I though Isis was the crank type not bb type – old BB is a race face external one with 24mm diameter at the bearings. So replacement should work with minor persuasion yes?

Aye, a light lube and ease it into her gently with a bit of tapping if she’s tight.

So that didn’t go well…knocked through the axle and it lifted out and cracked the (brittle) plastic drive side top hat type thing from the xtr bb….so it was too tight even though I’d popped the crank in the freezer for a bit. I tried tightening it up but there’s a small amount of lateral play in the driveside crank arm now.

Help – it’s a mates bike he stupidly entrusted me with!

If it has play, have you added enough pre load prior to tightening

http://www.parktool.com/blog/repair-help/external-bearing-crank-systems-hollowtech-ii-megaexo-giga-x-pipe-x-type-campagnolo-ultra-torque

Which version of Raceface crank? Mine tightens up to a “hard stop” and if there’s then play then it’s necessary to add in some crank axle shims. Do you have any of these?

race face x type – so no preload option

Don’t have any crank axle shims no – I suspect that is what was in there giveing the <24mm diameter which cracked when pushed out by the axle being tapped through.

Can you buy them>

The shims are for adjusting preload, not axle diameter. What BB spacers have you fitted? You may be able to fit an extra one and remove any axle shims already in place. The X-type cranks should fit into a Shimano BB just fine.