Thanks for the description of your application.
If the bike is rotating at fixed location with no turning left or right, for example the bike in the gym, then you can use BHI260AP smart sensor to get the dynamic and static angle of the crank directly. It doesn't matter if BHI260AP is mounted at the outer end or middle of the crank. The 1 ~ 2 degree accuracy could be achieved.
However, if it is a real bike running on the road with turning, then it is difficult to calculate the crank angle because the motion includes linear acceleration and centripetal acceleration. The 6DoF sensor fusion running inside BHI260AP cannot achieve 1 ~ 2 degree accuracy. You may need to look for other solutions.
I would really appreaciate your suggestion.
Is there some other information you need to reply?
I don't have other information to reply. But I am curious what you will do after you get accurate dynamic and static crane angle of a bike.