Читать книгу Proficient Motorcycling - David L. Hough - Страница 44

With carefully selected rake, trail, and tire profiles, a machine can have good self-balancing dynamics, whether moving upright and straight ahead or leaned over into a curve and turning, and whether at fast or slow speeds. The point I don’t want you to miss is that the front-end geometry is designed to balance itself. If the bike leans over to the right, the CP shifts farther right, steering the front wheel more toward the right. As the wheel tracks away from center, that rolls the bike back toward vertical. When the machine returns to vertical, the gravity, steering head position, and CP all balance again.

When the motorcycle begins to fall over, the location of the front tire contact ring moves slightly, increasing drag on that side of the tire and countersteering the front wheel back under the center of mass.

As the front wheel steers itself back under the mass, the bike is rolled upright and balanced again but on a slightly different path.

If you watch a motorcycle cruising down the superslab (freeway), you’d swear it follows an absolutely perfect straight line. But if you could measure accurately, you’d discover that it rolls ever so slightly from one side to the other as it balances itself, sort of like a clock pendulum. This self-balancing act is more obvious at slower speeds because the front tire requires greater steering input at slower speeds than at higher speeds to get the same effect.

If you were to ride your bike slowly through a puddle of white paint and then go back and look at the tire tracks, you would observe that the front tire sometimes tracks to the left and sometimes to the right. In other words, the front tire rolls along in a snakelike track as the bike continuously rebalances itself.