At the Tony Foale seminar earlier this week, we had the chance to talk to Rob Kasten, inventor of the reverse rotating brake rotors and also take an up close look of the rotors in action. Rob was there with his Kawasaki prototype and took a few spins around the parking lot. It is definitely an interesting visual experience to see the rotors going the wrong way but there is nothing in the appearance that looks cobbled together. If you didn’t know better, you would think it came from the factory that way.
According to Rob, the rotors are set up to spin at 2.7 times wheel rpm and, due to the mass of the rotors, cancel 70% of the gyroscopic precession of the wheel, dramatically reducing steering effort and increasing the speed at which he can flick the bike from side to side in quick transitions. On a high speed section of a track he is familiar with, the Kawasaki previously reached an indicated 145mph but with the reverse rotating rotors now tops out there at 140mph, so the gearing involved does extract a price. On the other hand, speed in the turns is quicker so you get something back.
When Rob took the bike around the lot and applied the brakes, you could just hear a high pitched whine, somewhat like a supercharger, coming from the gearing. Rob also notes the brakes are much more effective, taking far less pressure on the lever for a given amount of stopping power to be applied.
The prototype was built much stronger than it needed to be since they had no previous experience with the system and certainly would rather error on the side of overbuilding than risk coming up short. Once a production model is configured, the gearing size and weight could be reduced further enhancing performance.
What is the future of Rob’s system? Currently he is looking for investors or a manufacturer willing to incorporate the system into one of their bikes. It’s a very interesting concept and will probably need further head to head testing against an identical model without the system to see what the benefits and costs really are. We’ll keep an eye on this.
The Kneeslider: Reverse Rotating Brake Rotors
The Kneeslider: Reverse Rotating Brake Rotors 2
C. J. Luke, III says
The hp that it takes to turn the rotors backwards can be thought of as “braking” force being applied. That is to say, imagine going through a turn with a small amount of “front” brake applied.
In my mind, all of the negatives of this implementation don’t seem to give much return:
Pros
1. Less force on the brake lever to attain a certain braking rate.
2. Less effort to turn the bike.
Cons
1. More unsprung weight.
2. More moving parts to break.
3. More hp used to move the bike.
4. Additional friction load on the front tire.
In my opinion, the modern sport bikes of today will drop into a turn easily, and certainly will “out perform” all but the extremely proficient rider, so it offers no “improvement” for that large group of bike riders. The extra hp required for any given speed will be something that everyone will be able to experience (even squids) so I would think that would be a sever loss. The unsprung weight issue along with the additional “breaking” effect would seem to out weigh the possible improvement of being able to “flick” the bike into a turn easier.
But hey…it’s just my opinion.
aaron says
the only useful outcome I see in a racing application is that longer wheelbases can be used while keeping steering input about the same. this means less wheelies and stoppies – and (if the mechanical losses were brought under control, and the unsprung weight didn’t sabotoge any racing applications) I think this means more power could be extracted from top motors like motogp, because of less tendancy to destabilize the chassis under power. of course, in any other class, power isn’t really reduced very much except for reliability…. I exclude the 500rpm wide powerband “dyno dragster” bikes, of course…
Gordy says
If it was to be endurance tested it would surely require a lube system for the cogs? I would be concerned about component failure: something within the cog system jamming or failing while the motorcycle is at speed.
I will be surprised if any mass manufacturer bites the bullet. It would only make sense if the disadvantages opened up other areas where big gains could be made, and I just can not see it. The manufacturers have worked hard to reach the current level of high speed stability, and I do not think that they will want to add the mass, cost and complexity.
Nice idea, but I think it’s a solution without a problem!
JP says
It’s certainly a noteworthy engineering exercise, but I have to side with CJ above in wondering if the additional complexity and unsprung weight are worth the benefits. Also Gordy brings up a very worthwhile concern regarding lubrication. Let’s see some more of these in use, and get some hard data on durability and performance before jumping into getting them adopted by a major manufacturer.
Matt Fisher says
I could see this having a market in the cruiser/performance cruiser market.
The additional unsprung weight would be of little consequence on a 500-700lb machine, yet the additional braking leverage and lighter steering would be noticeable on such bikes. Then there’s the cool factor- the looks one could get while out on cruise night at very low speeds; kinda like the spinner wheels that are so popular with the “bling-bling” crowd.
From a pure performance perspective though, I’m betting the cons outweigh the pros.
Neil says
I don’t like this at all. As JP notes, it’s a great project to do for a thesis or similar but real world application is unlikely.
Maybe someone else will remember this too – some years ago a company, whose name I can’t remember, released a retrofit kit which used compound brakes. This uses multiple rotors of smaller diameter to reduce the gyroscopic effects. The designers originally worked on aircraft braking systems, where this type of system is apparently very common.
Does anyone know if the company is still around? Has anyone tried the product?
Jon says
The name of the company that Neil is thinking of is Beringer Brakes, http://www.Beringer.fr