CHEMISTRY INSIDE THE WHEEL: THE URETHANE MOLECULE [PART TWO]

The real artistry in making the ideal wheel comes in the choice of the A and B molecules. Long flexible molecules for B tend to give the urethane a low durometer - a wheel that is soft and grips the road. Choosing a rigid molecule for A tends to make the wheel stiffer. If you choose a B with lots of connection points, the result is a highly cross-linked elastic solid that is dense, strong, and very hard - a wheel with a high durometer will allow you to achieve higher speeds.

Arbor produces the Sucrose Initiative line of wheels. Ziegler explained that sucrose, common table sugar, acts like a B molecule with 8 places to form a urethane bond. This will make a wheel with many cross-links, which makes it firm. However, because of sucrose's flexibility, cross links in sucrose lend the wheel some flexibility. The multiple cross links increase the molecules strength, which makes a stronger wheel. This is why the Sucrose Initiative wheels leave fewer thane lines, extending the life of the wheel. Arbor created a fast wheel that grips the road with a long life span.

The urethane wheel has developed dramatically since the 70s and will continue to expand as the sport grows. Next time you ride, take a second to fully appreciate the chemistry that went into your favorite wheel.