Advice on first attempt at ultra simple motorcycle sim?

Good day.

I live in Canada, and I have a motorcycle which I love but can't use 4-6 months of the year. I'm thinking about buying a wrecked small sport bike, gutting the unnecessary components, and making it into a very cheap and basic motorcycle sim. I've looked at other threads on motorcycle sims, and they're all more ambitious than my current level of experience allows.

The only inputs I'm really after right now are an analog input for the throttle, a switch for the brake, and lean for the x axis. There's always the option of adding more down the road, but I want to keep it simple for now as this is a first attempt.

The lean is really the challenge. If the axles are fixed points, the rake should cause it to countersteer. The distance between the two pivot points would have to be able to shift for that to work. Changing the length from the handlebars to the pivot point would then allow me to adjust the ratio of steering to lean. I would need a spring system to force the bike upright, which could be two opposing springs or a single spring pushing the two pivot points apart. Either way, the spring would have to have an adjustable preload on it to allow me to fine tune how much resistance there is to lean. I'm hoping I could use the spring from the swingarm for this since the sim obviously wouldn't need suspension travel. The front suspension would probably help with that as well, now that I think about it.

If I take apart a joystick and mount it directly under the bike, a simple wooden dowel running up to a groove inside the frame should pass the lean angle down. Adjusting the distance between the contact on the frame and where the joystick is mounted would let me change change the ratio of bike lean to joystick input.

I was thinking of doing a simple 2x4 frame to support everything. I have no idea what to use for pivots and springs yet; I can picture what I want in my head but I haven't yet looked into what I could get as salvage that would do the job.

Since I have zero experience with this, I'm assuming there are a bunch of challenges and mistakes I don't know how to recognize yet. Is there any advice the community can offer to help minimize those?

Thanks!

Makes sense.

My initial thought of the front suspension resisting lean was flawed. It would resist turning the handlebars, but would do nothing to stop the bike from just falling over, so I think I would need to use a pair of coil springs pushing the bottom of the frame up.

The only issue I can see with the opposed springs like that is the amount of force needed to counteract the pull of each spring.

For example, in a lean your compressing one spring and stretching the other spring, the two forces would then in essence cancel each other out.

Unless of course the springs are floor attached and not bike attached, but then the spring would need to be flush with the bike frame to ensure good contact, then there is the challenge of ensuring the bike leans into the springs consistently... maybe a key way / groove system...

The only half decent attempt I saw at a bike sim was years ago back in the 80's at a local fair. Some guy essentially put a full bike (trail bike) on a rolling road (the kind to test the Horsepower of cars) and the bike was held in position by a large central spring. (Like the kids toys in parks) You then leaned on the bike naturally while the rolling road was what actually moved (up down, left right etc) to simulate movement. I was only a kid and can recall it being a great experience, but I've never seen another since!! It was a pre-programmed ride, the same video was shown over and over so you just followed the on screen movements. It certainly was no Sim, but the thinking behind it was neat!

No way... the things you find on YouTube. This was the ride, but the one I was on was on a spring and had sideways lean. However, this was certainly the base that was converted.... I assume the creator just modified the motion underneath to fire the up and down has needed, rather than the rocking observed in this clip.

There are a few units based on bike frames. There's a few homemade units closer to what I'm aiming for, a professional simulator made in Germany, and a university project out of Nottingham that used a Triumph superbike chassis. I tried linking them, but of course I'm not at the 10 post limit yet.

The hard part as I see it is creating a system that will allow me to lean the bike with springs or shocks trying to push it upright. Ideally, I want lean and countersteering linked, but I think enough opposing force holding the bike up will accomplish that.

I've been told that pneumatic shock absorbers might be better than springs, but I need a way of preloading them so they don't overextend. I'm not sure how to do that yet.

Join the club. I have loads of diagrams and ideas about my bike sim.

Springs..... think of them the other way. Instead of having springs vertically pushing and pulling the bike up and down. Think of a large flex coupler mounted horizontally along the bottom of the wheels. That's how I'll be doing mine. So basically a torsional spring in a horizontal tube mounted on a frame and the bike sitting on this. An alternative option is to have what would more or less be a dual mass flywheel at the front and back of the pipe.

That should allow the bike to self right

Forget the joystick in the middle because it causes too many angle problems, especially if you want the bike to move up and down. The tube in the frame which the bike is on can have a potentiometer to measure the lean angle.

Motors - mount them in the frame of the bike and in a simple way of putting it, use the existing suspension tubes as levers to raise and lower the bike under acceleration, braking etc.

I thought about that, but doesn't it require a much stronger base, since you're now pulling the base frame up rather than pushing it down into the floor?

A friend of mine suggested having the pivot point much higher, so you're fighting gravity when you lean, but I'm not sure that would feel right either.

What have your thoughts been in turns of handlebar position? Were you thinking of having it contribute to lean mechanically, or using it as a separate input?

Thanks again, everybody!

As far as the balance point goes, yes you will need a weighted base or slightly wider than a car sim but nothing major. You would still be having the weight of the sim on there and yourself as well.

The other option is that when you lean right, the base would effectively self center by sliding left (not yaw, but the whole base moving flat left) so your center of gravity is still in the middle of your frame/construction. This could be done fairly easily if you wanted to keep the base small. (sprung tube mentioned above + a couple of levers). I'll try and do a drawing of it later and post it up.

Higher pivot point might feel weird.

As far as a sim goes, if you play a bike game with a decent steering wheel it does a decent job of getting the lean angles. You could use the handlebars to contribute to the turning circle.... (lean angle + handlebar angle = total turning angle). But as a proof of concept or initial build to get it running. I don't think they would have to be used. Most arcade machines have fixed position handlebars.

This has started to get me thinking about mine again. And believe me, there's been a lot of thinking done!!!
I'll need to get my drawings out. I also need someone to donate a bike to use.

There's an inherent use for the handlebars because of the rake. When you turn the bars left, it will try to push the front pivot left, but since that's fixed it will actually lean the bike to the right. This changes the length of the front forks, but the beauty of using a real bike frame is that the front suspension will allow that.

Probably need a CV joint or something similar to allow the front axle to pivot.

I'm thinking there should be tons of wrecked Ninja 250s and CBR125Rs out there, but I'm going to go look today and see.

I had thought about using a ball joint for the front wheel. It would only have to move very slightly.

But it's one of those things where it will need a test fit to suss out the best way to fix it. Maybe the front forks and wheel could stay fixed and the top half of the forks and bar could turn independently. That might be much easier to implement in this case. It would certainly take a lot less engineering.

skip the first half . its different but looks good

Looks like my idea of the horizontally spring tube on the floor is already used on commercial machines.

I've just watched a lot of motorbike simulator videos and I've noticed a fairly consistent flaw with most of them. They don't lean very far. The one in the video posted above is the first one I've seen which has a huge range of motion with the lean angle. It goes right down like you would in a real race. I think this is essential to building a good bike simulator.

I see two issues though when using a lot of lean. The more lean the longer it takes to transition from one side back to the other which induces more delay when making quick right-left or left-right turns. Also, on a real bike, when turning centrifugal force causes your body weight to transfer down thru wheels and opposite of the turn. On a simulator there are no centrifugal forces so more leaning will cause your body to feel more sideways pull towards the ground instead, which is opposite of reality.

There's also an issue with lean if you aren't using a colossal screen - large amounts of lean will mess up your viewing angle.

I think my first attempt is going to have a high pivot point and rely on gravity to pull the weight of the bike and rider back down. The bottom of the bike will swing out rather than having the bike lean down. That should keep my view of the screen more consistent, and it provides an inherent increasing resistance to lean. As a fringe benefit, it would also keep the weight closer to the center so I wouldn't need as wide a base.

It also means I don't need to mess around with opposing forces yet. I'm sure that will happen down the road, but I just want a basic prototype to start.

If I replace the front axle with a longer bar, I can connect each end of it to cables running to the front of the base. That would cause the handlebars to pull on the cable and lean the bike. There are probably fancier solutions involving pulleys that I might look into.

I had somebody suggest trying to get a used Bowflex and using it as the spring to keep the bike level. That would allow for easy adjustment of how much force you want pulling the bike upright.

I see what you mean with the higher pivot.

I would forget about the screens. A short throw projector or VR solution would make more sense.

I suspect an Oculus Rift or something similar would be ideal, but that's something to plan for down the road. Baby steps.