What crankset does your bike have?

FSA Gossamer Cross

You'll have to be more specific. Does your FSA crankset have any identifying logos like 'BB30' or 'EVO386'? What PM do you have?

If there are no logos, the next option is to remove your crank and compare if the spindle diameter is similar to your existing PM. It's either 24mm or 30mmm, so the differences are pretty obvious to spot.

If both are 24mm, you're likely good to swap them without much hassle.

If they are both 30mm, check the length of the axel. Are they the same, or is one obviously shorter than the other?

In most case, it will be possible to get your PM to fit (you might have to buy a BB). The only case that would definitely not work is if your PM is BB30 and your frame is not. Given that your frame is PressFit, I doubt it follows the narrow BB30 design.

Good questions. I will have to look more closely at the stampings on the crank (if there are any) but if I knew that, I think I'd know my answer. I didn't know the 24mm and 30mm parts so thank you for that!

I have one PM that is MegaExo compatible (P2M) and another that is GXP (Quarq Riken AL).

MegaExo and GXP are both based on a 24mm axel diameter. So...

1. If your gossamer crank is the same diameter...
- the P2M should easily be swapped in.
- the GXP has a slightly smaller diameter on the non-drive side and you likely will need a small shim like this.

2. If your gossamer is larger in diameter (i.e. 30mm).
You'll need a new PressFit bottom bracket like this ...I like the press fit BB's that thread into themselves.

In either case, I would also assume that your PM's have larger chainring sizes than the gossamer cross. If that's the case, you'll also need to adjust the height of your front derailleur.

Thanks for the info. I've swapped several BBs and cranks but have never dealt with PressFit BBs that is new to me.

Regarding the Chainrings: you are correct. Truth is, really only my MegaExo PM is one I could effectively use on my gravel bike because it is 110 bcd while the Quarq is 130 bcd and I want to keep my 46/36 rings. I have some experience moving the FD around and readjusting since I do that some on my TT bike when I swap rings from 50, 53, 54.

Thanks for your help on this.