I’ve got a filthy (but still smooth) square taper BB that I need to fit to the bike I’m building for my other half. I’m a bit clueless as to how to fit it and can’t find any diagrams or how-tos that I trust to not be totally useless (as clearly I am myself).

Anyone able to point me at the right stuff or explain whether and what I need to dismantle any part of it before trying to fit?

One element of self-helpdesk here. Looks like the left hand adapter is what needs to come off, but I’ve no idea how to do it.

More info? Is it a cartridge type – ie in one main bit and a sleeve/cup for the LHS?

like this?

If so remove LHS cup, clean & grease all threads, screw unit into BB then screw LH cup in.

have a look at parktool.com – they have guides for pretty much everything.