I am thinking about getting a new bike but would like to keep using a power meter but can seem to figure out which ones are compatible with sram cx1 and x1 groupsets.
Its for my cyclocross bike so pedal based power meters are out of the question.
BB90 accepts the same axle as a standard outboard BB - 24mm crank axle.
I think there are two options..
Stages make a power meter that they list as compatible with Force and Rival groupsets. For a BB90, I think it would be the GXP option you're looking for. I would compare the axle/crank spline before buying it though as I'm unsure what the CX1 spline looks like.
Depending on your brake/wheel axle you could also use a Powertap hub. They make various disc and non-disc hubs in a range of axle standards and widths, so you may find something there. You would of course have to assemble it into a wheel, so that would bump the price of this option up a bit and might not be suitable if you're trying to keep the bike below a certain weight?
You say 'keep using a power meter', do you already have one? If so, which one?
Hope this helps!