If the bike suspension is too high, replace the original handling with this one in handling.cfg.

FCR900 500.0 190.0 3.5 0.0 0.08 -0.09 103 1.8 0.9 0.48 5 350.0 90.0 5.0 R P 60.0 0.50 0 35.0 0.85 0.15 0.0 0.15 -0.06 0.5 0.0 0.0 0.15 35000 1002000 2 1 1 4 

Optional:
Use the bikes.ifp provided if the player sitting postion isn't correct.