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I don't know where the term cupping came from.
If you were to flatten the tire so it contacted the ground flat like a tank tread, cupping would refer to a wear patter than looks like a saw blade from the side. It's caused by the most extreme forces in a tire being generated in one direction only. Since the front tire doesn't drive the bike at all, the extreme forces on the tire occur in braking and when leaned over on it's side.
I'll use braking as the example because it's easier to describe.
Go back to the tank tread analogy for a minute. When you brake, the part in contact with the ground stays stationary, while the bike and the wheel, and the top part of the tire continue trying to go forward. All of the individual sections of the tire tread are going to lean forward slightly while the top is being pulled in one direction and bottom in another. Of course the leading edge os going to dig in more, and the trailing edge is going to lift up slightly as the block tilts, so the leading edge wears faster than the trailing edge. All of this is going on in each individual block of the tire tread. After a while, the leading edge will be shorter, and the trailing edge taller, and when you have two sections side by side, there will be a difference in height from one tread to the next. (look at the above posted pictures again and it's pretty easy to see) This is what causes the tire to "hum" or "rumble." Of course the back tire wears in just the opposite direction because the strongest forces are generated in acceleration. When the rear tire is used to brake, it will wear in the opposite direction of when acceleration, so the overall cupping factor is less on the rear tire.
All tires will cup to some degree. Sport type bikes put a lot of force on the front tire in braking quickly, and the FJR is very heavy which only makes it worse. The tire tread pattern also makes a big difference.
Most importantly however is your riding style. If you gun and brake and gun and brake, and lean all the way over on the tire braking heavily, you'll cup your tires much faster.
If you were to flatten the tire so it contacted the ground flat like a tank tread, cupping would refer to a wear patter than looks like a saw blade from the side. It's caused by the most extreme forces in a tire being generated in one direction only. Since the front tire doesn't drive the bike at all, the extreme forces on the tire occur in braking and when leaned over on it's side.
I'll use braking as the example because it's easier to describe.
Go back to the tank tread analogy for a minute. When you brake, the part in contact with the ground stays stationary, while the bike and the wheel, and the top part of the tire continue trying to go forward. All of the individual sections of the tire tread are going to lean forward slightly while the top is being pulled in one direction and bottom in another. Of course the leading edge os going to dig in more, and the trailing edge is going to lift up slightly as the block tilts, so the leading edge wears faster than the trailing edge. All of this is going on in each individual block of the tire tread. After a while, the leading edge will be shorter, and the trailing edge taller, and when you have two sections side by side, there will be a difference in height from one tread to the next. (look at the above posted pictures again and it's pretty easy to see) This is what causes the tire to "hum" or "rumble." Of course the back tire wears in just the opposite direction because the strongest forces are generated in acceleration. When the rear tire is used to brake, it will wear in the opposite direction of when acceleration, so the overall cupping factor is less on the rear tire.
All tires will cup to some degree. Sport type bikes put a lot of force on the front tire in braking quickly, and the FJR is very heavy which only makes it worse. The tire tread pattern also makes a big difference.
Most importantly however is your riding style. If you gun and brake and gun and brake, and lean all the way over on the tire braking heavily, you'll cup your tires much faster.
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