I converted a Suzuka 8 hours years ago to work with a PC. I used a properly programmed arduino as interface.
I set up a couple of Moto GP games (don't remember, maybe moto gp '18) and Milestone's superbike 2000. My findings where that only superbike was playable. This was not because of the PC, nor the interface but the faact that motorcicle games optimized for gamepads are not "compatible" with a whole bike controller. Motorcicle games have a programmed lag intended to simulate a real bike. With a gamepad that lag is beneficial. With a full motorcicle controller (cabinet) you have an additional lag due to the cabinet inertia.
In other words simulation lag + cabinet inertia make those bike games unplyable on arcade hardware
Different is the case of arcade games such as hang on series, taito world grand prix etc. Those are still hard to play because of the cab inertia, but enjoyable.
Actually... even Arcade motorcycle games that had Sit on versions... were Impossible to play well.
A perfect example is Super Hangon. Ive played both the Standup and Sit-On version of it. The game itself, is downright Brutal in
its difficulty level.. and that is with the quick standup controls. Trying to move the cabinet with your legs... makes it impossible, IMO.
The problem is that the Spring mechanism cant replicate the quick self-righting nature of the spinning tires Gyroscopic nature.
A few ideas on building a functional sit-on controller:
1) Make the pivot closer to the center of the bike, and make the leaning mechanism resemble a Parallelogram... where you
shift the entire structure to the left or right.
2) A bit more crazy: Make an actual spinning tire, to act as a Gyroscope. The speeds would have to be dialed in, in such
a way.. that they are able to hold your mass up good enough.. but not so strong that you cant lean the bike. Again, you still
would likely have to raise the pivot closer to the center. This would probably require a Weight sensor in the seat. Tires would
have to be enclosed for safety. And it still might fail to work as expected.
3) Motor Driven mechanism. Sort of like a CNC machine. Depending on the Degree that you turn your handlebars... the
more that the bike will Lean. To be able to react fast enough.. you will probably need something like a Chain Drive mechanism,
and good strong gearing.
A good Counter-Mass system, might make physical transitions even more effortless, and speedy.
Now... to go all out... you would add a Z-Axis (height control) for Hill Simulation. One for each Tire. They might also serve
to act as road bump simulation (haptics).
If the Entire platform could rotate 360 degrees... you could also have a pretty realistic VR solution.
But the simple Parallelogram pivoting system, could be a pretty easy build... and give enough of good feel, that it satisfies most
peoples desires (just enough).