So the subject is interesting: you have what seems to be a comprehensible system relying on "classical" physics that were iron-clad over 100 years ago. But then you find things like a wiki page lacking even basic information and universities web pages and books by physicists getting really basic stuff wrong: usually first that gyro forces are necessary to keep a bike upright and stabilized (wrong, bikes with counterrotating wheels that cancel the gyro forces demonstrate rake and trail are fundamentally responsible for stability) and second that either precession or "stepping out" is the sole means by which countersteering happens (completely implausible when you consider the forces involved and the extreme rapidity with which a motorcycle can be leaned by torquing the bars). Even Wikipedia's page on 2 wheel dynamics and countersteering leave it at "Because the forces in the contact patch are at ground level, this pulls the wheels "out from under" the bike to the right and causes it to lean to the left".
That sounds incomplete and I propose a more complete story of how countersteering ACTUALLY works: the rate the wheel tracks out from under the bike into a radius at a given steering angle has a linear relationship with the bike's speed but the lateral acceleration needed to take that given radius grows exponentially with speed. This explains how the bike can quickly lean at high speed with barely any lateral counter-track, and how at low speed there is significant travel the opposite way as the bike is in the process of being leaned over.
Please critique or correct what I have written and use this thread to share other mysteries and explanations of 2 wheel dynamics. My next question: how does whipping (like in MX) work? Riders give terrible and inaccurate explanations as always. Is it purely precession? That is plausible for the initiation but I'm having trouble figuring out how the bike gets straight again as the riders are twisting the bars in such a way that precession doesn't seem to be the culprit at that point.
That sounds incomplete and I propose a more complete story of how countersteering ACTUALLY works: the rate the wheel tracks out from under the bike into a radius at a given steering angle has a linear relationship with the bike's speed but the lateral acceleration needed to take that given radius grows exponentially with speed. This explains how the bike can quickly lean at high speed with barely any lateral counter-track, and how at low speed there is significant travel the opposite way as the bike is in the process of being leaned over.
Please critique or correct what I have written and use this thread to share other mysteries and explanations of 2 wheel dynamics. My next question: how does whipping (like in MX) work? Riders give terrible and inaccurate explanations as always. Is it purely precession? That is plausible for the initiation but I'm having trouble figuring out how the bike gets straight again as the riders are twisting the bars in such a way that precession doesn't seem to be the culprit at that point.