There was a short note on Roadracing World yesterday about this patent application for reverse rotating brake rotors. There wasn’t much information and the website had no drawings of any sort. The idea seems sound, if you reverse rotate rotors in relation to the wheel, you cancel the gyroscopic precession, giving you the ability to change lean angles easily. I was trying to figure what sort of gear assembly would be required to pull this off and after rumaging around for the special plugin required I finally managed to look at the patent drawings.
The image shown here is one of several and there is no way to put the images on this site in a large enough format for you to make any sense of them. If you are interested in the actual images so you can figure out what they’re doing you’ll have to go to the patent office site and see for yourself. You can read the explanation behind the idea on the reverse rotating rotors site.
Links are no longer current. Reverse Rotating Rotors
C. J. Luke, III says
Conceptually, I have a few problems with this idea. I understand the “theory” , but I believe that there are drawbacks that override the gains. Technically, we have lightned the frontend (inverted forks, radial mounted brakes, and alloy wheels with less mass, in order to improve the responsiveness of the bike and front suspension. We have “floated” the rotor to improve allignment and breaking performance. Now we are going to add weight(the mechanism is definitely going to be heavier), and “fix” the rotor again, not to mention that the break pads are probably going to need to be in “front” of the fork tubes because of the reverse rotation, which will increase the “moment of inertia” of their weight.
In addition, although I admit that I am not a racer, I have gone out on track days, and I can’t remember a high speed turn that I ‘threw’ my bike into. What I am saying is that the ability to establish a radical lean angle quickly at 140, is not as great as the need to do it at 40. And we already have methods of dealing with tank slappers that don’t put the additional weight on the front axel.
Could be all wrong here….but I don’t think that this will make it big on the racing circuit.
Ian MacLeod says
Very interesting, but isn’t it funny how there isn’t much new under the sun. I saw a set of those on the front end of a Ducati Pantah racer in about 1978 at the shop of Keith Hart in Grimsby Ontario.
I still remember my surprise when Keith spun the front wheel….and the discs spun in the opposite direction. Those early Dukes needed all the help they could get to turn, and there might have been a bit of an anti dive effect or unbinding on the front forks
He took the bike to Daytona that year I believe. He was mysterious about them, but I assume that they came from the Ducati factory. Keith was one of the first Ducati dealers in Ontario and had some factory contacts.
I’m surprised to see that they’re being patented, having been kicking around for almost 30 years.
F1 Lotus says
MV Agusta tried this on their road racing bikes in the mid / early 70’s, around the time they also tried aerodynamic ‘winglets’ on the front forks, I beleive Phil Read was their #1 rider during this period?
Ian MacLeod says
Wait a sec. I never even thought about this. The reason that a bike will lift the back wheel under heavy front braking, is the forces fed into the calipers by the front wheel, which rotate the motorcycle forward and up around the front axle.
Now if you reverse the rotation of the discs, would you not get the opposite effect? The bike would rotate around the front axle, but in the opposite direction, and squat at the rear and probably experience a slight lift at the front?
I may not have a grasp of the physics involved, but this would seem to be something worth exploring. It changes some very established chassis dynamics in some fairly mature technology. Thoughts?
C.J. Luke says
Well, it doesn’t supprise me that there is plenty of “prior art” and they still got a patent. Our patent system is in a ‘really poor state of repair’ right now.
As for the reverse effect on the dynamics of the front end during braking….I hadn’t considered that…but it seems to me that it would only serve to put a ‘reverse flex’ in the fork tubes as the main forces are still going to be the inertia of the bike and rider. The primary force is generated by the friction of the tire on the road trying to asorb the inertia.
The main problem seems to me to be the size of the gears/mechanism that are reversing the rotor. Modern bikes have more ‘horse power’ in the breaks than in the engine…i.e…they can stop faster than they can accelerate. Seems like that would take some beefy gearing.
kneeslider says
That gearing issue occured to me, too. Since you’re no longer exerting the braking force directly to the wheel but through the gears instead, either you need some gears made out of unobtanium or they’re going to be heavy or weak.
aaron says
Ian said-
“The bike would rotate around the front axle, but in the opposite direction, and squat at the rear and probably experience a slight lift at the front?”
the bike tries “to stoppie” because the of the stopping force applied to the bikes through the contact patch. the bikes Cg, being higher than the line of force applied at the contact patch, is subjected to a torque, and tries to turn about it’s Cg. the greater the stopping force, or the greater the lever arm, (height of Cg) the more rotation you’ll get.
besides, friction varies with the normal force. if the bike rotated it’s mass towards the rear, you’d get less normal force, therefore less available friction, (“tire stick”) and less braking availablefrom the front wheel. (even at near lockup) not what you’d want from an “improved” braking system. rear wheel braking would improve in this case though…
Hangtight says
Don’t forget that with the planetary gearing shown it would be possible to stepup (or down) the rotation speed of the disc relative to the wheel. Higher speeds mean lower loads (power = force x distance moved), greater effective swept area and hence smaller pads/ calipers for the same breaking effect. Thermal mass would become an issue. hmm carbon/ carbon brakes on discs that do 10,000 rpm?
Robby says
It works. Of course it adds wieght. Yes the rotors will spin faster. Stoppies are a result of wieght transfer and have nothing to do with which direction the brakes rotate. It does not matter where the calipers are located (as long as they grab the rotors). You pull harder on the bars than you think you do even to change lean angle at 40mph. I never heard of any attempt at this before but it is my understanding that they thought it was an anti-dive solution. It has nothing to do with dive. All of the forces are contained in the lower fork just as before. The point is that the gyroscopic precession of the front wheel is canceled out on the same axis with a mass that you must spin anyway. It makes a massive difference and the prototype will prove it.