11-24-2015, 01:30 PM
Tire does not stop; it is constant rotation while rolling. But. If you draw a line from rim to rim, imagine that line rolling around with the tire. That line comes into contact with the road within the tire patch area (an elongated ellipse because the tire in flexible so we have a patch contact are instead of a point like you would get with an ideal rigid circle).
While the line is in contact with the road (assuming perfect friction and we're not burning out or slipping around) the line and road remain in static contact as the tire travels over it. As the the bike moves forward, if you had an imaginary camera pointed at the line it would appear that the line slides across the patch - but really the patch is moving.
The line rises up, rotates around and gets another shot at touching the road. In the mean time, the tire keeps spinning around, and, hopefully for your health, the patch remains in contact with the road. It's not unlike interlocking gears, They spin, teeth pushing each other around while momentarily in contact but not stopping.
While the line is in contact with the road (assuming perfect friction and we're not burning out or slipping around) the line and road remain in static contact as the tire travels over it. As the the bike moves forward, if you had an imaginary camera pointed at the line it would appear that the line slides across the patch - but really the patch is moving.
The line rises up, rotates around and gets another shot at touching the road. In the mean time, the tire keeps spinning around, and, hopefully for your health, the patch remains in contact with the road. It's not unlike interlocking gears, They spin, teeth pushing each other around while momentarily in contact but not stopping.