ulrichw

In the article, it says that Robbie Kasten (the inventor) believes that he can trim the weight significantly from the prototype. The problem is that these rotors may not be legal in many racing classes, so it's hard to see how they'd catch on (and their usefulness for street-only bikes is less obvious). -- Ulrich

Ok, I finally located the article I'd read on this technology. The article is in the Nov. 2006 issue of Roadracing World (Volume 16, Number 11) It's on page 16 and is titled "Precession, Gyroscopes And Reverse Rotating Front Rotors", by Sam Fleming. Unfortunately, I can't find an online copy of this article. Here are some quotes: "... I began to step up the pace into the four fast lefts of Jennings' back straing. With the extreme rake and trail set-up on the bike, and the absence of a steering damper, I was worried about stepping up the pace, since I fully expected the bike to go into an unrecoverable tankslapper going through the fifth-gear sweeper. However, no matter how hard I drove through the lefts, the bike remained stable and responsive." "Eventually I was giving it the full-race throttle-pinned-catching-spped-shifts-pass-two-bikes-pull-back-onto-the-race-line-no-brakes-catch-a-downshift-and-flick-hard-left-hard-right treatment. The bike remained absolutely stable through out it all. no weave, no wobble, no drama. And this was not on a well-set-up racebike. This was on an OK set-up track day bike with no steering damper" Elsewhere he mentions the greatly increased braking effect, because the rotors are moving 2.7 times as fast as the wheel (the ratio that the inventor chose to balance out the gyroscopic forces from the front wheel - note that the rotors are canceling out only about 80% of the gyroscopic forces, not all of them). On the negative side, the significant increase in unsprung weight caused the bike to feel the bumps in the track a lot more. Sam Fleming appears to have raced in WERA. -- Ulrich

You're quite welcome. Here's a motorcycle-usa article on the bike with the reverse-rotating rotor, btw: http://www.motorcycle-usa.com/Article_Page...3207&Page=1 -- Ulrich

Unfortunately countersteering is not explicitly discussed in the context of the gyroscopic argument. I would argue, however, that the same forces that keep you balanced when you're upright would also be used to unbalance you into a lean. The website discusses countersteering under the heading "counter-intuitive", but unfortunately does not include mention of the zero-gyroscopic argument. Nonetheless, I believe that if there had been a significant difference in how the zero-gyro bikes steered, that would have been mentioned in the article and would have resulted in causing a lot of difficulty for the people who tried to ride the bike. For another corroborating website, see here: http://www.reverserotatingrotors.com/mythbuster.html This person has designed brake rotors which partially counteract the gyroscopic action of the wheel by reverse-rotating the brake rotors through an ingenious set of planetary gears. The page I linked has a brief reference to countersteering and gyroscopic precession, although it's not as explicit as I'd like on the subject of precession. I've read a roadtest of this bike that concluded that the setup improved rideability (but I haven't been able to locate it online as of yet - I'll look again and try to link it). Again, this is a strong argument against gyroscopic precession as the primary mode of steering (this inventor in fact argues that precession gets in the way of good handling, and is a primary cause of tank-slappers). I do realize that much of this argument is academic - it doesn't change the inputs required by the rider, which you and Woody both accurately described, I believe. It will be interesting to see what Keith and/or Will will have to say on this topic. -- Ulrich

I believe you're correct on the first half of your last sentence (no opposite torsion is needed), but incorrect on the second half (the turn is achieved by gyroscopic precession). Please follow the link I posted - the experiments were carried out by a professor of mechanical engineering - a person I would say has better credentials than even practitioners of motorcycle racing - his experiments debunk gyroscopic forces as the primary forces in controlling a two wheeled vehicle. Note that that doesn't mean that gyroscopic forces have no effect - just that they're not the real explanation for how a bicycle or a motorcycle handles. Here's the explanation of where the "opposite" force comes from to turn: - The contact patch of the front tire is slightly behind the steering axis (this is the "trail" of the front suspension as Woody mentioned) - When you're going straight, the force on the front wheel is in plane with the steering axis, because the gravity vector is in line with the motorcycle. - When you lean to the left, the force on the front wheel is no longer in plane. The "equal reaction" force of the ground on the contact patch is still vertical (i.e. perpendicular to the ground), but because the bike is leaned, this ends up pushing the contact patch to the right of the plane of the motorcycle. - Since the contact patch is behind the steering axis, pushing the contact patch to the right pushes the steering to the left. - This applies the force that actually turns the wheel into the turn, changing the path of the motorcycle. - In order to continue increasing the lean angle, you need to keep applying right pressure - but instead of actually turning the wheel to the right, you're simply counteracting the force applied to the left from the effects of the trail and the lean. -- Ulrich

The video was one of the best things about the explanation. Otherwise I found that it covered things at a high-level and not as accurately as many sites out there. Unfortunately, the video was also "borrowed" without attribution. Find the original at this site: http://www.gotagteam.com/ - bottom of the page under "countersteering 101" (and for entertainment, I highly recommend the race reports there) For the second half of this thread - I have to side with Woody. Gyroscopic forces appear to be a secondary factor in the steering of bikes. For good in-depth coverage of this, see here: http://www.losethetrainingwheels.org/defau...Lev=2&ID=34 At this site, they document experiments with bicycles which eliminated all gyroscopic force (by cancelling them out with reverse-rotating wheels of the same configuration as the regular wheels), and showed that they could still be easily ridden and even ridden with no hands. Unfortunately, there's usually a lot of pseudo-science used in explaining motorcycle dynamics (e.g., when explaining the dynamics of peg weighting, hanging off, counter-weighting, lean angle etc.) Here's another analogy to counter-steering: - Human beings balance similar to bikes. You'll notice for example, that runners lean into a turn (they have to, for the same reason bikes do - they'd fall to the outside of the turn if they tried to stay upright). - Now, think about a running back in football who wants to cut to the left. He will initiate his cut by planting his right foot to the right of his path of travel. - This "plant" is homologous to the counter steer. By putting his foot out there, he initiates a lean to the left (the lean angle is the angle between the ground and the line between the base of his foot and his center of mass). - This lean let's him apply the centripetal force that initiates the turn Note that Woody correctly explained this in his first post - he's not disputing countersteering, he's just disputing gyroscopic precession as the primary phenomenon that makes countersteering work (correctly, in my opinion). Here's another way to visualize countersteering: Instead of thinking of the direct action on the handlebars, think of it as riding the bike out from under you. When initiating a left turn, effectively, you're putting the bike on a momentary path to the right to get it out from under you. Since you stay closer to your original path than the path the contact patches follow, the bike ends up leaning to the left. Now, you'll end up turning your handlebars slightly to the left to "catch" your fall to the left (i.e., the lean), and assuming you dial in just the right amount of steering will enter a steady-state turn to the left. -- Ulrich

Can't answer in general, but at the two-day camp I attended, the bike was not set up for individual students that I know of. At the camp I attended there were two run groups, and each bike was shared by two students in the different groups. Since you'll probably never be running 10/10ths during the school, I would imagine that settings "in the ballpark" are sufficient. FWIW the bike felt great to me (of course it was only the third bike I'd ever ridden, so YMMV). Of course, I weigh 165lbs, which makes me around 180 with gear - the weight which corresponds to what I understand is often the "default" setup for bikes. -- Ulrich

When I took the school in November, they just had me sign a credit card slip. Presumably if you're not paying by credit card they'd look for some other deposit. Each day (whether in a 2-day camp or otherwise) is one level. So you'd leave the 2-day camp at level 2 (meaning you'd go into level 3 the next time you take the course). Because the ratio of students to teachers is good at 2-day camps (2 students per teacher when I took it), you'll get a lot of individual attention. -- Ulrich