Hopefully someone can help me here.

I’ve got a Salsa Bucksaw carbon coming tomorrow and I’ve got the bottom bracket to go in but it comes with a spacer. I’ve googled and I’m not sure if I should use the spacer or not?

The Bucksaw has a PF41 BB.

The cups press straight in and there is probably a centre tube between them.

Not sure what you mean by a spacer – which BB and cranks have you got?

BB instructions should specify what/where spacers are needed e.g. it’s a lot more critical on SRAM/GXP that it is with HT2 or Raceface due to the way that bearing axial play is accommodated.

RaceFace cranks and BB? I spent a while worrying about this before fitting an Aeffect crank to my Beargrease. Can’t remember what I did in the end, but neither I, my cranks, my BB or my frame have died (yet).