I was watching a video (tweaked) where by the XRT did a substantial portion of the drag strip on only two wheels.

The interesting thing was, the driver seemed to be able to make minor adjustments to the cars direction using the steering, despite the fact the wheels were no longer on the ground.

Does this mean gyroscopic wheel physics are simulated?

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If so, the FXO wheels, being about as wide as Jennifer Lopez's sitting equipment (Don't be fooled by the rocks that she's got, she's still, she's still Jenny from the block.) must require a secondary engine in order to power the steering pump. I sure hope it has VVTi. :|
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lol, no it doent, that was probably just some little bug in the tweaking, or his patch

Bumps and changes of traction may account for the change of directions, as could assymmetrical tyre pressures or cambers.

But I don't think gyroscopic forces are modelled - the motorbikes made using tweak apparently suffered for it (although that was S1, and S2 is quite a bit better, yet I see no real reason for it's inclusion in LFS at the moment).

a bike can perfectly stay upright with 0 gyroscopique effect, tire model forces tend to keep the bikes upright when rolling.

The driver's body moves when you steer, as (obviously) do the wheels. The shift in weight will transfer to the back wheels (probably more noticable when turning away from the driver side) and cause a slight change in direction, even with the steering wheels off the ground.

Or am I wrong?

Uh oh, sounds like the countersteering thread all over again

As for gyro, I'm sure it has an effect. Ride a moped (with small wheels) then ride a proper bike (with larger wheels). The moped will be 'twitchier'.

Or, ride a mountain bike (big wheels) then one of those silly looking stunt bikes with small wheels, and you'll see there that even at push bike speeds gyroscopic effect is pretty pronounced.

Quote from tristancliffe :

Or, ride a mountain bike (big wheels) then one of those silly looking stunt bikes with small wheels, and you'll see there that even at push bike speeds gyroscopic effect is pretty pronounced.

Sounds morer like Caster work to me

Quote from [RF]-art555 :

Sounds morer like Caster work to me

nope ... even if you spin something as small and light as a cd you get some surprisingly strong gyro forces

I don't think there is a gyroscopic model either, I was thinking about it the other day while some people were jumping off of the Fern Bay jump, and they'd roll just as easily with or without power down.

Quote from XCNuse :

I don't think there is a gyroscopic model either, I was thinking about it the other day while some people were jumping off of the Fern Bay jump, and they'd roll just as easily with or without power down.

there is something far more important than gyro forces that bugs me about jumps
wheels dont seem to have any moment op intertia ... or at least i sure have never seen any effect of braking or stepping on the gas pedal while airborne

Quote from Shotglass :

there is something far more important than gyro forces that bugs me about jumps
wheels dont seem to have any moment op intertia ... or at least i sure have never seen any effect of braking or stepping on the gas pedal while airborne

They do...try it with the car on its roof.

i did ... with the bf1 having the speedo at ~800 ... no noteworthy effect

Quote from Shotglass :

there is something far more important than gyro forces that bugs me about jumps
wheels dont seem to have any moment op intertia ... or at least i sure have never seen any effect of braking or stepping on the gas pedal while airborne

The wheels claim to have moment of inertia. For the FXR, J=1.407132 kgm2 for each wheel. The unsprung mass is 23.52824 kg

If we assume the wheel mass is 15 kg (leaving 8.5 kg for the suspension uprights and brakes) and further assuming that all the mass of the wheel is concentrated at one radius, we can calculate that this radius is 0.306 m. The actual rolling radius is for the FXR is 0.346 m, so the numbers seem to be sensible. Whether or not they're modelled correctly is another matter.

Oh, and gyroscopic effects have no effect on the stability of bicycles

Quote from StewartFisher :

Oh, and gyroscopic effects have no effect on the stability of bicycles

Ummm.....

I hope your smiley means you're not being serious.

Quote from Cue-Ball :

Ummm.....

I hope your smiley means you're not being serious.

No. Have a look at this page made by one of my university lecturers:

http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

He's quite a character...it's amazing how someone can get so excited about spinning things.
Strictly speaking the gyroscopic forces do have an effect but it's very small, and it is dominated by other effects.

"My point is that gyroscopic effects are not needed to keep you from falling over when you are riding in a straight line. I am not saying anything about what happens when you actively wish to steer away from straight ahead."

btw i think rfactor has these gyrothingies!1

Quote from Resound :

They do...try it with the car on its roof.

That isn't gyroscopic forces, that is the forces of the engine output.
Someone else can give you a better meaning, I just know it is the engine's rotational force turning the car over; kind of like torque steer I guess it could be considered.

That isn't gyroscopic though, gyroscopic keeps things from moving, not.. making things move.

Quote from StewartFisher :

No. Have a look at this page made by one of my university lecturers:

http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

He's quite a character...it's amazing how someone can get so excited about spinning things.
Strictly speaking the gyroscopic forces do have an effect but it's very small, and it is dominated by other effects.

Yeah, it's true that on a typical pedal bike, gryoscopic effects are fairly small. The same is not true of a motorbike at moderate speed. http://www.superbikeschool.com/machinery/no-bs-machine.php

Quote from tristancliffe :

Uh oh, sounds like the countersteering thread all over again

As for gyro, I'm sure it has an effect. Ride a moped (with small wheels) then ride a proper bike (with larger wheels). The moped will be 'twitchier'.

Or, ride a mountain bike (big wheels) then one of those silly looking stunt bikes with small wheels, and you'll see there that even at push bike speeds gyroscopic effect is pretty pronounced.

i'm a biker since several years, almost ten, before that i drove bikes and 50cc motorbikes.
I didnt said that gyroscopic a no effect, just saying that IF you could have a tire with 0 mass = 0 gyroscopic effect, bikes would still stand upright when rolling, because tire forces from tire friction tend to keep the bikes stand upright when tires are rolling, and those forces are way more bigger than gyroscopic effect

That's why, even with 0 gyroscopic effects simulated in LFS you could simulate motorbikes with no problems That's all a was saying , nothing more, nothing less

Then why are bikes harder to balance stationary? (both cycles and motored) Surely it's because at speed the gyroscopic forces help you. What else changes in terms of balancing?

You can't steer when you're stationary. While riding you can steer to help keeping the bike upright. When you're riding faster you don't have to steer that far (or quick) to get the same effect, so it's easier.

Quote from tristancliffe :

Then why are bikes harder to balance stationary? (both cycles and motored) Surely it's because at speed the gyroscopic forces help you. What else changes in terms of balancing?

If you add slip angle in front wheel by turning bars left, you generate a big lateral force. you turn bars left, you create a big left force, as contact patch is below gravity center, it create a big torque, wich lean the bike to the right ( counter steering ).
At stationary, tire forces is NULL, no lateral force to help you.

Just asks Vehicle Physics is my job

Ahok, thanks!

Can you then explain why things with small wheels (mopeds, BMXs) are twitchier and harder to balance than big wheeled bikes (superbikes, mountain bikes) at similar speeds?

it's works with every things that is taller, taller = higher cg.
Higher cg means, object need less forces to counter steer gravity that act on cg and make the bike lean ( fall ).
Now if you remember some circus show, there some acrobats that drive bikes with small wheel but very high chair, and they have no problem to stabilize.

Same with those stilt legs stuff , longer stilt = easier to keep in balance.

Also there's obviously stuff about tire contact patch size.. but i think it is less revelant.

Ah, I see. Thank you for the correction.