This is something that's always bothered me with inertia actually. You have to measure rotation against a frame of reference right? The way I frame the problem

This is something that's always bothered me with inertia actually. You have to measure rotation against a frame of reference right? The way I frame the problem is generally by imagining a gyroscope (say, a spinning bike wheel) somewhere in the universe far away from any galaxy or massive body. Relative to which frame of reference will it maintain orientation?