Hi.
You could maybe use some triggers. if you are rotation the root you might need to do some trick.
basically have 1 parent. then have 1 trigger that will rotate.
Then some other triggers that will count the rotations.
The one rotation should be rotation with the bike, if you can't do it directly on the bike then use get/set rotation (get from bike / set to collider)
I think this system can even do more that only registering flips.