Ha ha ... note that while he has been very analytical in most ways, he has nothing to say about the gyroscopic precession effect! Note also that in the two reasonably successful examples he shows, the adverse effect of "wrong way" precession has been minimized by making the rear wheels very small and low mass.Mark wrote:Here's a link on this topic.
What's seldom realized is that turning a bike is similar to turning an airplane: you don't turn a plane by stomping on one rudder pedal, you bank it so that part of your lift becomes a centripetal force that accelerates you smoothly around a center point. Similarly, you turn a bike by banking it, so that part of your weight is converted to a centripetal force from the street into the bike at the wheel contact points. One time, I happened to see a motorcyclist make a low-speed snap turn at an intersection such that the angle of the bike centerline was no more than 45 degrees from the pavement. If he had hit a patch of grease or sand, he'd have killed himself doing it - the sidewise force of a 45-degree bank is equal to the full loaded weight of the vehicle !!! The force felt by the rider would be 1.41 Gs (not downward, but outward and downward through the bike CL toward the contact point).
Riding in an airplane making a properly balanced 60-degree(!) banked turn, the coffee in your cup will stay level with the brim, and the cup will not slide on your tray - but it will "weigh" twice as much if you pick it up to drink from it. Needless to say, an airline pilot will never make such a turn under normal circumstances, but the plane is perfectly capable of a 2G turn and much more. No bike could make such a turn on an ordinary flat surface, but could do so on a banked track, I suppose.
When my dad would take me through the midway of the Iowa State Fair, I always wanted to see the guys who ride motorcycles around the inside cylindrical surface of a giant "barrel". While the speeds are not really very high, they must be operating at 3 or 4 Gs to do that [pulling blood away from your brain toward your seat], since the cylindrical wall was only about 20 ft (6 metres) across, possibly less. Traction was not a problem, of course, because the wall was perpendicular so as to be flat "under" the bike - the ultimate "banked turn". There was a small conical "ramp" zone at the bottom of the cylinder for getting started and stopping. As a kid, I was mightily impressed by such a feat. My dad was not as easily impressed, especially when the operators invariably 'passed the hat' during the performance for some extra cash beyond the price of admission. This was for the "riders insurance fund". Ha.