Interesting and odd

[Admin Jaap]

Don't know about the technology, but that website layout sais "don't take this seriously..."

[pete roper]

It's bollocks.

85551[/snapback]

 

Sorry, I gotta agree. It's just another clever bit of show-offy munt for dipsticks with too much money and not enough sense. I can't for the life of me see any benefit that wouldn't be outweighed by the extra weight.

 

I think the counter-rotating mass issue is a furphy too, compared to the weight of a wheel and tyre I'd think the rotor mass would be comparatively small, (although all the gears and shit would increase it considerably.) and it's closer to the wheel axis so it's effect is going to be minmalized by that.

 

It's also worth remembering it's the gyroscopic effect of the wheels that prevent you falling over! You've got to have some mass in 'em or your machine would be unrideable.

 

At the end of the day even if id did *work* who needs it??????

 

Pete

[DeBenGuzzi]

Sorry, I gotta agree. It's just another clever bit of show-offy munt for dipsticks with too much money and not enough sense. I can't for the life of me see any benefit that wouldn't be outweighed by the extra weight.

 

I think the counter-rotating mass issue is a furphy too, compared to the weight of a wheel and tyre I'd think the rotor mass would be comparatively small, (although all the gears and shit would increase it considerably.) and it's closer to the wheel axis so it's effect is going to be minmalized by that.

 

It's also worth remembering it's the gyroscopic effect of the wheels that prevent you falling over! You've got to have some mass in 'em or your machine would be unrideable.

 

At the end of the day even if id did *work* who needs it??????

 

Pete

85577[/snapback]

Ah-F'n-Men brotha

[Guest ratchethack]

Sorry, I gotta agree. It's just another clever bit of show-offy munt for dipsticks with too much money and not enough sense. I can't for the life of me see any benefit that wouldn't be outweighed by the extra weight.

 

I think the counter-rotating mass issue is a furphy too, compared to the weight of a wheel and tyre I'd think the rotor mass would be comparatively small, (although all the gears and shit would increase it considerably.) and it's closer to the wheel axis so it's effect is going to be minmalized by that.

 

It's also worth remembering it's the gyroscopic effect of the wheels that prevent you falling over! You've got to have some mass in 'em or your machine would be unrideable.

 

At the end of the day even if id did *work* who needs it??????

 

Pete

85577[/snapback]

Ah, Pete - thanks for the wisdom that nails this one down properly.

 

To effectively counter the combined rotating mass of wheel and tire with any device confined to normal disk diameters, you'd need to add considerably greater mass than the combined mass of wheel and tire, AND/OR counter-spin it at considerably higher speeds.

 

I just took another run at the Web site and saw the bit about counter-spinning the disks at higher speed than stock. OK. So now all they need to do to make their claims at all valid is to make up for the tremendous mass differential on the counter-rotating side of the equation by adding flywheels made out of something like depleted uranium to the disks.... To be really effective in achieving their claims, this would require an impressive set o' Queen Mary-class boat anchors... Now considering the Guzzi's bevel box at the rear, this would create quite a polar moment of inertia - a stability trade-off that I'll let go - thanks just the same...

 

It's also a good point to make that the trememdous gyroscopic effects of the wheels and tires contributes greatly to stability at speed. In my dirt-riding days, when the rule o' thumb that could (and often did) save y'er butt was "when in doubt, hit the gas", it's the only thing that kept me from a very short riding career many a time...

 

Fun thinkin' outside o' the box, though.

 

Burt Rutan has always been one o' my favorites, too!

[dlaing]

At the end of the day even if id did *work* who needs it??????

85577[/snapback]

Stupid people like me who get airborn at 120+MPH, landing in a speed wobble, and thanking myself for shelling out the money for the Ohlins that probably made the difference between life and death.

Ohlins steering damper is now on my wish list, and if this thing actually works, I may be in line to buy it.

[dlaing]

To be really effective in achieving their claims, this would require an impressive set o' Queen Mary-class boat anchors...  

85584[/snapback]

Bullocks!

FWIW I roughly calculated the gearing from their image to be a little more than twice as fast as the wheel....something like a 2 to 5 ratio.

Tire weight is about 15#

Tire is spinning with its center mass at a radius of maybe 25cm.

Wheel weight is about 10# (not including their patented spinning gears)

Wheel is spinning with its center mass at a radius of maybe 15cm

Brake weight is about 8#s (4lbs per rotor for 320x4mm), (not including their patented spinning gears)

Brake is spinning with its center mass at a radius of maybe 12cm

I am not sure the following math is correct, but if we take

(15x25= 375) + (10x15=150) = 525

and compare it to (8x12=96)x5/2=240

If you add the forces of a normal wheel you would get 375+525+96= ~1000

This wheel assembly would have a force of very roughly 525-240 or ~285

So, 100MPH would feel like 28.5MPH (if you don't include the effect of the rear wheel)

On their website they say it reduces it to the effect of a five pound wheel, brake and tire assembly.

So I would guesstimate 5x20=100 so my math is very different than theirs.

Perhaps tires weigh much less than 15#

A 8# tire would be 8x25=200, 375-200=175 and 285-175=110 or very close to their 5lb claim.

Add 320x6mm rotors and their 3lb claim may make sense.

[Guest ratchethack]

Bullocks!

Hmmmm....well I must admit that every time I look at the site, I seem to be able to see it in a different way and reverse engineer it a bit more. Too bad they don't have one single photo that would explain it all. Why do you suppose THAT is?? Could it be that the sight of all those gears and bearings might be a tad intimidating and/or dubious relative to cost (in both weight and dollars) and potential benefit??

 

Now it appears to me that what I referred to as "planetary" gears are in fact fixed (immobile WRT the fork lowers), and that the large internal gear is fixed in the wheel hub. The center gear drives the rotors, and the speed differential between stock rotors and the reverse-rotating rotors is determined by the ratio of the number of teeth of the large internal gear to the number of teeth of the center gear. I found it impossible to count the teeth from the photo's, but as you've suggested, it may in fact be something like a 5:2 ratio.

So....my math is very different than theirs.

Dave, WRT your math, lets begin with your use of term, "center of mass". The center of mass of the tire, wheel, and rotors is all the same - it's the axis of the wheel. What I think you mean to focus on is the "polar moment of inertia", which is not and cannot be known for these components by simply knowing either their mass or weight. Without knowing the PMI of each, calculations on the amount of precession and gyro effect are pointless.

 

So lacking the specifics required for calculation purposes, let's just deal with generalities. As Pete has noted recently in the "Performance Mods" thread, we won't be making any changes to the laws of physics here or anywhere else, no matter how much wishful thinking we can heap up in one pile. However, application of general principles can be used to make valid assumptions that may lead us in the right direction after all.

 

Does it make sense that the polar moment of inertia of a wheel and tire can be significantly offset by the counter-rotating PMI of disks, disk carriers, and the shafts and bearings that they spin on if they counter-rotate at a 5:2 ratio to the wheel? Well, it seems to me that to some degree, this would certainly be true. But critical questions remain unanswered at the Web site:

 

To what degree?, and

 

At what cost? (in both added unsprung weight and dollars)

Add 320x6mm rotors and their 3lb claim may make sense.

Is your interpretation of what they mean from their Web site here:

 

"The prototype reduces the gyro precession of the front wheel assembly of the zx6r to the equivalent of a 5 lbs assembly (tire,wheel and rotors). The best moto gp technology is about 17-18 lbs. When we fit it to the zx10r it will be equivalent to what a 3 lbs. assembly would be due to the zx10r's larger rotors."

 

- that the counter-rotating disks at 5:2 ratio nullify all of the precession and gyro effects - and all of the PMI of tire and wheel - all except for a remaining 3 lbs., and that the best moto gp technology reduces this to only 17-18 lbs.?

 

Well, it doesn't quite add up or make sense to my way of thinking, even without knowing the PMI of the components and thinking only in a general way about it. But why do you suppose they are using weight instead of PMI figures, given by a set of equations which I suspect are quite a bit beyond the evidently competent machining abilities of your heroes to calculate?

 

And why do you suppose that there are no weights given for the (presumably) hardened steel gears, bearings, and shafts that their assembly obviously adds? Seems to me that the gears, bearings, and other components of gear-driven brakes would need to be even more robust than the equivalent components of a transmission, due to the fact that brakes typically out-accelerate (in the negative direction, of course) any motor-driven vehicle in the positive direction.

 

Now, barring any substantial factual proof that any of this stuff is really effective and "worth" the offsetting cost in unsprung weight - let alone monetary cost, if you've REACHED OUT WITH YOUR FEELINGS, if you've drunk all the kool-aid, and are absolutely convinced in a very substantial way of their claims that:

 

1. Every motorcycle needs it!

 

2. Reduced steering effort!

 

3. No tank slappers!

 

4. Better brake performance!

 

Well, I reckon you're exactly the kind of a prospective customer they're lookin' for!

 

By all means, go for it and let us know how it works out next time you get y'er Guzzi crossed up in the air at 120 mph!

[dlaing]

Hmmmm....well I must admit that every time I look at the site, I seem to be able to see it in a different way and reverse engineer it a bit more.  Too bad they don't have one single photo that would explain it all.  Why do you suppose THAT is??  Could it be that the sight of all those gears and bearings might be a tad intimidating and/or dubious relative to cost (in both weight and dollars) and potential benefit??  

85634[/snapback]

Could be.

Probably if you do a patent search you could find more detailed images

 

Dave, WRT your math, lets begin with your use of term, "center of mass".  The center of mass of the tire, wheel, and rotors is all the same - it's the axis of the wheel.  What I think you mean to focus on is the "polar moment of inertia", which is not and cannot be known for these components by simply knowing either their mass or weight.  Without knowing the PMI of each, calculations on the amount of precession and gyro effect are pointless.

85634[/snapback]

I cannot disagree with complete certainty, but the center of mass that I speak of is the center mass point of the sweeping radius(not diameter) that is having a change in direction that creates the force.

I think it would be very difficult to calculate it with great accuracy, but I suspect the the force is directly proportional to mass, how far out that mass is, and how fast the mass is spinning.

I proved to myself that their numbers could be accurate.

You may write it off as being pointless, but I doubt you can prove it is pointless.

ia of a wheel and tire can be significantly offset by the counter-rotating PMI of disks, disk carriers, and the shafts and bearings that they spin on if they counter-rotate at a 5:2 ratio to the wheel?  Well, it seems to me that to some degree, this would certainly be true.  But the question is - to what degree?

85634[/snapback]

I thought I answered that, but I suspect since I don't exactly know what a polar moment of inertia is, I could be wrong.

Is your interpretation of what they mean from their Web site here:

 

"The prototype reduces the gyro precession of the front wheel assembly of the zx6r to the equivalent of a 5 lbs assembly (tire,wheel and rotors). The best moto gp technology is about 17-18  lbs. When we fit it to the zx10r it will be equivalent to what a 3 lbs. assembly would be due to the zx10r's larger rotors."

 

- that the counter-rotating disks at 5:2 ratio nullify all of the precession and gyro effects - and all of the PMI of tire and wheel - all except for a remaining 3 lbs., and that the best moto gp technology reduces this to only 17-18 lbs.?

 

Well, it doesn't quite add up or make sense to my way of thinking, even without knowing the PMI of the components and thinking only in a general way about it.  But why do you suppose they are using weight instead of PMI figures, given by a set of equations which I suspect are quite a bit beyond the evidently competent machining abilities of your heroes to calculate?

85634[/snapback]

Yes, that is what I used and it makes sense to me.

Probably most of their audience will lose interest if you discuss PMIs

They do not say a three pound wheel with the mass at the perimeter or at hub, and from my very rough calculation, their 3lb estimate could easily be properly calculated.

I did not even begin to calculate in the spinning gears that would at more counter force.

 

And why do you suppose that there are no weights given for the (presumably) hardened steel gears, bearings, and shafts that their assembly obviously adds? 

 

Now, barring any substantial factual proof that any of this stuff is really effective, if you've REACHED OUT WITH YOUR FEELINGS, if you've drunk all the kool-aid, and are absolutely convinced of their claims that:

 

1.  Every motorcycle needs it!

 

2.  Reduced steering effort!

 

3.  No tank slappers!

 

4.  Better brake performance!

 

Well, I reckon you're exactly the kind of a prospective customer they're lookin' for!

 

By all means, go for it and let us know how it works out next time you get y'er Guzzi crossed up in the air at 120 mph!

85634[/snapback]

 

1. False

2. True

3. unsure, but I understand why it would help, but I have no plans to test it doing triple digit two point landings.

4. True

[Guest ratchethack]

I proved to myself that their numbers could be accurate.

That's fine, Dave - with all due respect. And yet, lacking credible physics to work with, (sorry, again - any calculation that ignores moment of inertia here is pointless) and lacking anything that even appears like it could be solid evidence of the theory in practice, others including myself remain unconvinced...

You may write it off as being pointless, but I doubt you can prove it is pointless.

Oh, but I beg you differ, Dave... It's certainly provable as pointless to those who understand moment of inertia. Using the moment of inertia of each component, the degree of offset of precession and gyro effect of counter-rotating parts at a 5:2 ratio can be calculated with great precision in this case. (You can look this up - there are many explanations and examples on the Web...f'er example: http://kwon3d.com/theory/moi/meas.html (scroll down the page to circular ring and circular disk - got y'er calculator handy? )

I did not even begin to calculate in the spinning gears that would at more counter force.

No point in doing so. The way I've reverse engineered it and now understand it to work, the only counter-rotating gear is the small one at the hub, which would add negligible polar moment of inertia in the counter-rotating direction. The "planetary" gears have no counter-rotational value at all, being fixed WRT the fork lowers. However, the moment of inertia of the large internally-toothed gear in the hub would be much more significant, its mass being significantly farther out from the axis, and therefore adding even more of a PMI in the same rotational direction of the wheel - increasing the rotational mass that's the whole point of the device to offset in the first place!

 

2. True

4. True

Based on what - if not simply their sales claims?

[Ballacraine]

In search of a problem that isn't there, if you are riding properly...on the road at least IMO.

 

The way I see it is something more to wear out and / or give trouble.

 

I am a great believer in the acronym KISS.

 

Keep It Simple, Stupid!

 

Nige.

[dlaing]

The way I've reverse engineered it and now understand it to work, the only counter-rotating gear is the small one at the hub, which would add negligible polar moment of inertia in the counter-rotating direction.  The "planetary" gears have no counter-rotational value at all, being fixed WRT the fork lowers.  However, the moment of inertia of the large internally-toothed gear in the hub would be much more significant, its mass being significantly farther out from the axis, and therefore adding even more of a PMI in the same rotational direction of the wheel - increasing the rotational mass that's the whole point of the device to offset in the first place! <_>

85640[/snapback]

How funny, I assumed just the opposite, that the brakes would be attached to the ring gear and the wheel to the hub gear

I guess we may never know.

[dlaing]

Oh,  but I beg you differ, Dave... It's certainly provable as pointless to those who understand moment of inertia.  Using the moment of inertia of each component, the degree of offset of precession and gyro effect of counter-rotating parts at a 5:2 ratio can be calculated with great precision in this case.  (You can look this up - there are many explanations and examples on the Web...f'er example: http://kwon3d.com/theory/moi/meas.html  (scroll down the page to circular ring and circular disk - got y'er calculator  handy? )

85640[/snapback]

I don't think the moment of inertia is the thing to focus on.

Check out this extrapolation:

It is defined that:

torque = force * radius

moment_of_inertia = mass * radius^2

angular_momentum = moment_of_inertia * angular_velocity

given that:

torque = moment_of_inertia * angular_acceleration

we can extrapolate that:

force * radius = mass * radius^2 * angular_acceleration

force = mass * radius * angular_acceleration

So, then the question is, which measurement corresponds to the force that we must overcome? torque or force or angular_momentum?

http://kosmoi.com/Science/Physics/Mechanics/tpecp2.shtml

Perhaps I the positioning of the mass to a greater radius does not increase linearly but rather exponentially????

Then if I recalculate, again roughly:

FWIW I roughly calculated the gearing from their image to be a little more than twice as fast as the wheel....something like a 2 to 5 ratio.

Tire weight is about 10# (reduced from 15#(it is going to wear, right?))

Tire is spinning with its center mass at a radius of maybe 25cm.

MOI = Mass x (r1^2 +r2^2) /2 and the tire is out a radius of maybe 22 to 28cm so MOI = 10 x (22^2 + 28^2)/2 = 5x(484+784)=6340

Wheel weight is about 10# (not including their patented spinning gears)

Wheel is spinning with its center mass at a radius of maybe 15cm, but to calculate the MOI is difficult, but just for giggles, let us humor you and assume the mass of the wheels is all in the perimeter, which it is not, we get 10x22^2 or 4840=MOI

Brake weight is about 8#s (4lbs per rotor for 320x4mm), (not including their patented spinning gears)

Brake MOI is 8 x (16^2 +12^2) /2 = 4x(256+144) = 1600

So comparing the MOIs 6340 + 4840 =11180 the 1600 is not much, but when we increase it by the 5/2 we get 4000, still less than half of what we need to get to their 5# claim. Maybe they are using 8#wheels and 7# race tires or something????

In any case you may be correct that they are exaggerating the gains that we will see.

Add 320x6mm rotors, a ten pound ring gear, countering a 15# combined weight for a race tire and $10,000 carbon fiber wheel, and you might have a shot at what they claim, but that would not be honest if they do not qualify it. Furthermore, the disk brake they show in the prototype looks more like a 290mm than a 320mm....what are they thinking?!?! They should be using a single tungsten steel 375mm perimeter rim brake rotor and get it spinning at three times the wheel speed!!!!

It seems to me that bigger diameter is better for the reverse rotating brake and that only having one rotor would be advantageous to keeping the design simple.

[Guest Nogbad]

Well, when it comes to brakes, you can't beat the brembos on the V11. These have progressive power, excellent feel and can be operated with finesse.

 

Way better than the "innovative" inverted perimeter disc on my XB12 which is wooden in feel and offers little in the way of feedback. I hope it will improve as it beds in.

 

I think the last thing you want in a brake is some clattery indirect gearbox crap between it and the wheel. Once those gears are worn I'm sure it would be worse than a floating disc with knackered bobbins.

 

I reiterate - It's ABSOLUTE bollocks and the last thing you want on your bike.

 

And another thing, cancelling out the rotating mass isn't the only consideration (if indeed it would be beneficial at all which I don't accept) what about unsprung weight (bloody important if the wheel is to track the road surface properly).

 

This idea is COMPLETE BOLLOCKS and should be binned. Hardly worthy of the length of this thread!

[mike wilson]

This sort of stuff always reminds me of someone's description of the Vincent.

 

"A collection of solutions, hurtling down the road looking for a problem"

[Guest ratchethack]

How funny, I assumed just the opposite, that the brakes would be attached to the ring gear and the wheel to the hub gear 

I guess we may never know.

In fact, we do know. If we assume that the correct ratio between rotational velocities of the brakes and wheel is 5:2, as you proposed, and the brakes were attached to the internally-toothed ring gear as you also proposed, the brakes would be spinning at a 2:5 ratio to the wheel - less than half stock speed instead of more than double.