Its a car, and it would turn like a car. You can't counter-steer on 4 wheels...
Submitted by babychaos on Fri, 2008-03-07 09:38
Are you sure? It's not got a fixed wheelbase? I'd need to see it moving.
Submitted by brainwipe on Fri, 2008-03-07 09:54
On bikes you turn left to go right, and vice versa. It works as you have single contact point to pivot on... the only way that works in cars is powersliding, as you have multiple pivot points...its more akin to a skateboard than a motorbike in that regard...
Submitted by babychaos on Fri, 2008-03-07 10:57
Hmmm, I see your point. A good point it is.
Still a cool vehicle.
Submitted by brainwipe on Fri, 2008-03-07 11:09
I don't see your point.
You turn left to go right on a bike? Do you?
Admittedly my experience is limited on motorbikes, but it never seemed that way to me on my bicycle.
I'm not sure I understand what you're on about.
Speedway riding? If so isn't that just like power sliding a rear wheel drive car round a bend with opposite lock on.
I think I'm misunderstanding you.
Submitted by baron on Fri, 2008-03-07 11:43
Apart from at very low speeds (as in upright), you turn on a motorbike with a combination of shifting weight, and counter-steer. You tend to do it without thinking about it (and when you learn you are actively encouraged not to think about it either, as bad things tend to happen), but hand on heart, to turn left on a bike you push the left handlebar away from you.
Cars turn by changing the angle of 2 parrallel wheels (as this thingy does), which moves the pressure to the outside wheel, initiating the turn. Skateboards turn by changing teh wheelbase on the side you want to turn to (so making the distance between the left wheels closer). This thing does a combination of car and skateboard, but not bike (unless you are on a suffieciently low-friction surface to have a single pivot point, at which point you swap over to powersliding and countersteer).
//added. The thing about mass movement is also why Simpson will never go on the back of my bike ever again. He actively moves his mass the wrong way...causing the wikipedia described straight line syndrome...
Submitted by babychaos on Fri, 2008-03-07 11:54
So - I don't know the specifics of this ... um whatever it is, but I don't see that four wheels would necessarily preclude counter-steering. All that's required for it to work is that the vehicle is unstable on the left-right axis and maintains sufficient traction while leaning. If a vehicle was designed with enough independant suspension on the two sides then I don't see why it wouldn't work.
added: Of course, I don't know why you'd want to. If you've got four wheels, you can probably engineer something that isn't unstable on the left-right axis. And if you want something unstable, because it's more fun, then why have four wheels in the first place?
...because you have parrallel tyres. Look at whats happening to the back wheels in the diagram...they have to go sideways to maintain the line, hence the need for low friction. Doable, but not advised on the road.
The big difference is that with bikes you have to use mass to turn, with parrallel wheels you lock the wheels the right way, then counter it. With bikes you have to do it to turn, with 4 wheels its an unrequired, and often unplanned extra...the back wheels follow the front ones, and the 2 pairs of wheels (left and right) follow different path.
//added (to reponse to the added). I agree. Effectively what you need to do to replicate a bike is make one side pointless in the turn, and given thats the most dangerous point of bike riding, its no safer (in theory less safe, as you've overcomplicated the entire process). Its also far more weight, so a self-defeating purpose as well. You would have more contact patches, so could get more power down (a limitation on acceleration on most sports bikes), but again the added weight of the wheels and suspension probably counters that.
Submitted by babychaos on Fri, 2008-03-07 12:20
Topic updated. :)
Submitted by brainwipe on Fri, 2008-03-07 13:04
Well that's something new learnt for today. Makes sense I guess, but apparently done with out thinking by me.
Comments
Its a car, and it would turn like a car. You can't counter-steer on 4 wheels...
Are you sure? It's not got a fixed wheelbase? I'd need to see it moving.
On bikes you turn left to go right, and vice versa. It works as you have single contact point to pivot on... the only way that works in cars is powersliding, as you have multiple pivot points...its more akin to a skateboard than a motorbike in that regard...
Hmmm, I see your point. A good point it is.
Still a cool vehicle.
I don't see your point.
You turn left to go right on a bike? Do you?
Admittedly my experience is limited on motorbikes, but it never seemed that way to me on my bicycle.
I'm not sure I understand what you're on about.
Speedway riding? If so isn't that just like power sliding a rear wheel drive car round a bend with opposite lock on.
I think I'm misunderstanding you.
Apart from at very low speeds (as in upright), you turn on a motorbike with a combination of shifting weight, and counter-steer. You tend to do it without thinking about it (and when you learn you are actively encouraged not to think about it either, as bad things tend to happen), but hand on heart, to turn left on a bike you push the left handlebar away from you.
http://en.wikipedia.org/wiki/Countersteering
Explains it in much more detail than you'll ever need to know.
Cars turn by changing the angle of 2 parrallel wheels (as this thingy does), which moves the pressure to the outside wheel, initiating the turn. Skateboards turn by changing teh wheelbase on the side you want to turn to (so making the distance between the left wheels closer). This thing does a combination of car and skateboard, but not bike (unless you are on a suffieciently low-friction surface to have a single pivot point, at which point you swap over to powersliding and countersteer).
//added. The thing about mass movement is also why Simpson will never go on the back of my bike ever again. He actively moves his mass the wrong way...causing the wikipedia described straight line syndrome...
So - I don't know the specifics of this ... um whatever it is, but I don't see that four wheels would necessarily preclude counter-steering. All that's required for it to work is that the vehicle is unstable on the left-right axis and maintains sufficient traction while leaning. If a vehicle was designed with enough independant suspension on the two sides then I don't see why it wouldn't work.
added: Of course, I don't know why you'd want to. If you've got four wheels, you can probably engineer something that isn't unstable on the left-right axis. And if you want something unstable, because it's more fun, then why have four wheels in the first place?
It works a bit differently with 4 wheels...
http://en.wikipedia.org/wiki/Opposite_lock
...because you have parrallel tyres. Look at whats happening to the back wheels in the diagram...they have to go sideways to maintain the line, hence the need for low friction. Doable, but not advised on the road.
The big difference is that with bikes you have to use mass to turn, with parrallel wheels you lock the wheels the right way, then counter it. With bikes you have to do it to turn, with 4 wheels its an unrequired, and often unplanned extra...the back wheels follow the front ones, and the 2 pairs of wheels (left and right) follow different path.
//added (to reponse to the added). I agree. Effectively what you need to do to replicate a bike is make one side pointless in the turn, and given thats the most dangerous point of bike riding, its no safer (in theory less safe, as you've overcomplicated the entire process). Its also far more weight, so a self-defeating purpose as well. You would have more contact patches, so could get more power down (a limitation on acceleration on most sports bikes), but again the added weight of the wheels and suspension probably counters that.
Topic updated. :)
Well that's something new learnt for today. Makes sense I guess, but apparently done with out thinking by me.