I really think there is no better motorcycle game then Tourist Trophy IMO.
It has gorgeous physics which works absolutely perfectly with the controller.
Prerequisite is usage of "full physics" model with separated brakes (front-rear), manual gearing, manual changing of the driver body-stance (straight back/leaned back) and analogue steering.
Once the full-physics controls are mastered the ride over Nurburgring becomes an unbelievable experience.
Also it has pretty decent career mode with great challenges. Only drawback is number of AI opponents, which is sadly only 3 (due to RAM constraints, heavy load of GT4 engine to RAM because of physics and lightning and fully animated drivers).
But IMO nothing even comes close to TT.