An interesting short read:
http://jalopnik.com/5604345/how-one-man-reinvented-the-wheel (http://jalopnik.com/5604345/how-one-man-reinvented-the-wheel)
It made me wonder about the possibility of have a motorcycle wheels mounted in forks in such a way that the wheel is not always parallel to the fork tubes. I picture the axle being mounted in elongated holes and hydraulic pressure keeping the wheel in place where it normally is, but when the bike is leaned over the wheel would not lean quite as far as the rest of the bike. Just a weird thought that came into my brain as I was reading the article.
sac
^
That's actually an interesting idea.
Where is Duck-Stew to try it?!!
cambered wheels are quite interesting. I've long discussions with my best friend who is an Indy Car (well, sort of this season. He had a ride for the 500 and a ride for 3 races coming up) driver about it. It is amazing how much effect it can have on performance.
Quote from: SacDuc on August 05, 2010, 11:41:35 AM
An interesting short read:
http://jalopnik.com/5604345/how-one-man-reinvented-the-wheel (http://jalopnik.com/5604345/how-one-man-reinvented-the-wheel)
It made me wonder about the possibility of have a motorcycle wheels mounted in forks in such a way that the wheel is not always parallel to the fork tubes. I picture the axle being mounted in elongated holes and hydraulic pressure keeping the wheel in place where it normally is, but when the bike is leaned over the wheel would not lean quite as far as the rest of the bike. Just a weird thought that came into my brain as I was reading the article.
sac
Bad idea for a motorcycle, I think. At best, it would just dampen rider input and, more likely, facilitate spectacular tank slappers.
Interesting thought on the motorcycle tire, even though I kind of think the inventor's claims on the automotive product are pretty snake-oily. Since the tire is going to be scrubbing substantially whenever it's moving (even in a straight line), I can understand why he didn't put up numbers to back up his claims of improved fuel mileage and tread wear, because it can't happen. And on the tests where there is published data, an R-compound Optima Camber tire outperforms an O.E. tire.... well, yeah, that's what R-compound tires are for! I understand how negative camber works to improve traction in race applications, but here the tires start out flat (even though they've got different diameter inner & outer sidewalls) so in hard cornering you're right back to running on the outside edge of the tire instead of the fuller contact patch a negative-camber race set-up gives you. Unless, of course, you set up your negative camber wheels with a few degrees MORE negative camber!
I do see one huge market for these tires though -- if they ever make it to market, I bet low-rider customizers snap them up, and mount them "inside out" to further accentuate the whole smashed look!
As for motorcycles & the idea of a wheel that changes angle in relation to the frame & rider... that'd be one funky bike, but as a thought exercise it's a lot of fun, with some big advantages immediately apparent. If I read you right, the idea would be that the tire would stay in a more vertical orientation in a turn -- maybe even fully vertical -- while the bike and rider leaned over. The cross section of the tire would therefore be a lot flatter than a current motorcycle tire -- a lot more like a car tire -- so you could get a huge contact patch, and so much higher cornerspeeds in any corner where traction is the limiting factor.
And since your lean angle would not pivot around the contact patch on the ground but several inches higher -- heck, maybe even as high as the axle -- your cornering clearance could be insanely high --- or it might be severely limited by the big old bow-legged fork tubes needed to accommodate the wheel tilting back and forth. It's easier for me to visualize the rear swingarm -- it'd have to be a shaft drive, if the engine & rear wheel aren't going to stay in the same plane, and the rear suspension & forks would have to work somehow throughout the whole range of lean angles.
It'd be less challenging (but still way difficult) to engineer a bike that allowed the wheels to tilt just a few degrees in cornering, basically limiting their travel to the current layout of fork & swingarm -- it might work with letting the wheel pivot a couple of degrees against stout, short springs in response to cornering forces (Turn left, for example, and a spring at the left end of the axle compresses a cm or so, to let the wheel stay more upright). But even then you'd need to have the brakes & disc follow the angle of the wheel, and a super-flexy cush drive so that the front & rear sprockets stay aligned while the back wheel tilts.
Hmmm, it's fun to think outside the box, and a good thing nobody's life depends on my (nonexistent) engineering skills.
Noooooo, you don't want a motorcycle tire to remain vertical in a turn. It's the tire lean that facilitates the turn. You couldn't turn as tight without leaning the tire. That's why a motorcycle tire has a "round" cross section vs. the flatter cross section of an auto tire (much different dynamics.) The contact patch doesn't really change that much and it increases, if anything, as the tire leans.
Quote from: Johnny OrganDonor on August 05, 2010, 03:23:34 PM
Noooooo, you don't want a motorcycle tire to remain vertical in a turn. It's the tire lean that facilitates the turn. You couldn't turn as tight without leaning the tire. That's why a motorcycle tire has a "round" cross section vs. the flatter cross section of an auto tire (much different dynamics.) The contact patch doesn't really change that much and it increases, if anything, as the tire leans.
Yup-a more vertical moto tire would give one a smaller contact patch.
Quote from: MrIncredible on August 05, 2010, 05:28:59 PM
Yup-a more vertical moto tire would give one a smaller contact patch.
That just sounds too damn obvious when you put it that way. Good thing I build houses and not rockets. ;D
sac
Quote from: MrIncredible on August 05, 2010, 05:28:59 PM
Yup-a more vertical moto tire would give one a smaller contact patch.
Unless it didn't look like a current motorcycle tire -- if it had a flat profile like a car tire, your contact patch could be several orders of magnitude larger than anything possible with a round profile moto tire.
I'm not saying this could or should happen in the real world; SacDuc's original musing "what if" got me wondering about what would be different with wheels that could remain in a more vertical axis and it was kind of a fun game.
I don't think a bike would be able to turn at all without a rounded profile. When you lean into a turn, the contact patch area on the front tire is moving faster than the contact patch area on the back tire, which enables the bike to go in a non-straight direction. It is kinda the same concept as a differential on a car - the wheels need to be moving at unequal speeds to enable a change in direction.
Quote from: il d00d on August 06, 2010, 07:51:06 AM
I don't think a bike would be able to turn at all without a rounded profile. When you lean into a turn, the contact patch area on the front tire is moving faster than the contact patch area on the back tire, which enables the bike to go in a non-straight direction. It is kinda the same concept as a differential on a car - the wheels need to be moving at unequal speeds to enable a change in direction.
Oh, no, I can definitely turn a car with a welded rear end.
Quote from: il d00d on August 06, 2010, 07:51:06 AM
I don't think a bike would be able to turn at all without a rounded profile. When you lean into a turn, the contact patch area on the front tire is moving faster than the contact patch area on the back tire, which enables the bike to go in a non-straight direction. It is kinda the same concept as a differential on a car - the wheels need to be moving at unequal speeds to enable a change in direction.
Side car motos have car-like tires and turn fine.
I don't agree that the contact patches are moving different between the front and rear wheels. The diameters of each are the same...and they are on the same line through the corner, so they should be very close to the same speed. Even if they are different I don't think it makes a difference, as the wheels aren't attached to each other (front and rear) like they are across a car axle, so they can rotate independently regardless of tire shape. Differentials on a car axle make the ride smoother because the wheels are travelling together and linked, but the outside one is going a greater distance in the same time, requiring the differential to allow it to rotate faster than the inside one. This doesn't apply to motos.
I think that with this idea of cambered tires that we would see a much more rapid tread wear on ther tires than standard tires. Here's why: With a cambered tire like this the outside edge of the tier has a greater circumference than the inside, with the axle tilted (cambered) in at the top this would not be a big problem if the car were always turning away from the side that the tire was on b/c it would cause the two sides of the tire to come in contact with the ground at the same rate (due to the turn). However cars go straight . . . a lot. . . so when the car is going straight the outside part of the contact patch (having a greater circumference) has to travel at a different rate then the inside of the tire b/c of the size difference. What we end up with is the inside and outside edges of the tire traveing at different speeds inrelation to the ground, this leads to increased tread wear on the extreme inside and outside of the tire. The middle of the tire would not wear as fast as the rest b/c it is going at an average speed (the speed of the car) whereas the edges must move faster and slower (respectively) in order for the tire to rotate and not disintegrate, which is not what I am proposing so don't throw this out of perspective.
Does this make any sense at all? Help me figure this out, or help me try to figure out how to explain what I am saying better. Maybe nobody whio would buy this tire would care b/c cost for new tires more often (and these will be expensive, at least at first) isn't a real concern for them.
The Doc
Let me try that again.
When you lean into a turn, the contact patch area on the front tire is moving faster than the contact patch area on the back tire, which enables the bike to go in a non-straight direction. I am pretty there needs to be a change in the speed differential between the front and back wheels when counter-steer is initiated. To be honest, I am not sure if that is a cause or effect of counter-steering, but this is kinda moot. Point retracted.
The difference in speed between the inside and outside of the tire is needed to make maintain a curve. It is like rolling a cone on its side. The outside of the cone is traveling faster per rotation than the inside of the cup. I am not sure how this same effect would be accomplished with a flat tire on a motorcycle - there would have to be some other way to achieve the cone effect, or the differential effect on a car.
Quote from: MrIncredible on August 06, 2010, 08:02:27 AM
Oh, no, I can definitely turn a car with a welded rear end.
Sure, until the pushing force from the rear wheels is greater than the traction of the front wheels? It is why we can turn left to go left at at slow speeds, but we have to counter-steer at higher speeds.
Quote from: Triple J on August 06, 2010, 08:13:01 AM
Side car motos have car-like tires and turn fine.
....Differentials on a car axle make the ride smoother because the wheels are travelling together and linked, but the outside one is going a greater distance in the same time, requiring the differential to allow it to rotate faster than the inside one. This doesn't apply to motos.
The point about differentials was that the wheels need to be able to operate at different speeds - and on bikes, parts of the tires need to be able to rotate faster or slower than other parts of the tire- in order to allow for and maintain a change in direction. I think side cars are different only in that there is another force acting on the same basic mechanism. The riders provide centripetal force -lean into the turn- which is what a single rider would do to turn a bike.
But you're right, the wheels on a bike rotate independently so, it was kind of a piss-poor attempt to illustrate my point. A car achieves the cone effect with equal sized wheels on both sides by making the outside wheels go faster -via the differential- than the inside. A bike achieves the cone effect with a rounded profile tire.
*...if I understand all of this correctly. I am not a physics professor, except sometimes on the internet.
Long story short adding negative camber essentially makes your tire wider with out having to get a wider rim. Also this tire would only work if the car in question had little or no roll. When a regular car goes around a bend the car rolls to the outside and thus "eating up" the negative camber causing premature wear on the outside of the tire. In a race car this concept would prove more suitable since they are designed to stay square thru a turn.
But if we put them on a plane on a conveyor belt, would it take off?
Here we go again.... [roll]
Quote from: MrIncredible on August 06, 2010, 10:58:14 AM
But if we put them on a plane on a conveyor belt, would it take off?
no but it will get fantastic life out of it's tires
Quote from: MrIncredible on August 06, 2010, 10:58:14 AM
But if we put them on a plane on a conveyor belt, would it take off?
[laugh] [laugh] [laugh] [laugh] [laugh] [laugh]
Greatest...........
Thread.............
EVER!
I hear Ducati is putting a motard on a conveyor belt.