My 2013 Niner SIR 9 frame came with a Niner branded FSA headset. At least I think that is who makes it based on the fact that on the Niner website they show FSA headsets sold separately. I have a Niner steel rigid fork that I want to use for this frame and it already has a Cane Creek crown race reducer on it.

I have done some searching on MTBR and it appears there may be some cases where the bearing angles are different but it is confusing. I am hoping someone with some experience on the subject might know the answer to the question below.

My question is, can I just use that or do I need to buy a FSA crown race reducer instead?