Steps to reproduce :

- open the attached project & scene
- enter play mode. Use the arrow keys to move the bike
- select the quad bike and change the mass to 1, the wheels will not apply the correct force on the bike
- stop play mode and change the mass to 1
- enter play mode and compare the behaviour of the bike with the previous test
- revert the mass to the original value
- enter play mode
- use the button to change the mass. It will disable -> change the mass -> enable the bike
- this time it will work as expected