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https://youtu.be/rDJZjdKai24Read the comments section, too.
Well one thing for sure, it's hard to argue the point that he's not a superior rider on a superior bike, over the others on the track.
I say that this a good demonstration of the physics point that the traction available from a skinny tire is as good as from a fat one. The reasons why he won instead of just held even with the others are different, of course!Moto
Is it? (Honestly asking).I mean, there are weight and power differences, so the loads were likely very different right? That same tire type/size probably wouldn't have worked as well on those sportbikes I assume?(sorry if I just opened a big bag of "I'm not gonna understand the physics of the answer")
I'd better tread carefully here. I'm no expert, but I did buy, partly read, and then misplace a book, Motorcycle Dynamics by Vittore Cossalter, that I vaguely recall treating this topic. The principles as I recall them seem simple enough. The area of the contact patch is proportional to the load at any particular inflation pressure. In essence the area times the psi must equal the load. This means skinny tires and fat tires, surprisingly, have the same contact patch at the same inflation pressure. So far, so good.Fat tires, however, can be run at lower pressures without the risks to carcasses and rims that would be entailed with skinny tires. So they have larger contact patches in practice.But here comes the real surprise. As the pressure of the tire on the pavement (the psi) increases, so does the coefficient of friction of the tire, in linear (as I recall) proportion to the pressure. So the higher psi that a skinny tire in practice runs results in a smaller contact patch with an exactly offsetting increased coefficient of friction. Hence, it doesn't matter for friction whether you run a fat or skinny tire.That is why the flat track bike can corner as well as the sport bikes (and the others). And also why the sport bikes could corner as well on the skinny tires provided they could achieve the same lean angles we see on the flat bike while running those tires (which they couldn't).There are a couple of reasons to run fat tires on a sport bike. One is less tire wear due to a greater amount of rubber on the road, and lower pressures. Another is handling, since the bike rides up on the sidewalls in cornering, making greater lean angles available for relatively wide bikes. (This is not an issue for the very thin flat track bike, as we can see.)As for power, it makes no difference for cornering speed. Traction is traction, and what doesn't go to cornering is available for acceleration, and vice versa. In the race video it is surprising and maybe suspicious that the sport bikes don't take more advantage of the straights, where they do have more power available since their traction is not going to cornering. But the straights are extremely short, and the riders don't seem as aggressive as they should be. The sport bike riders probably have to be extra careful with their throttles compared to the flat tracker.In a longer race I would expect the higher loading per square inch on the flat track bike's tires to cause them to wear out quickly. But in the 4100 meter race this doesn't seem to have been an issue. EDIT: And the lower weight of the flat track bike also reduces the loading per square inch, compared to a heavier bike.That's all I've got. I can only hope to find that book if need be!Moto
I wonder what would happen if they ran a few laps in the other direction.
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