Up to the late 60s, wheels were manufactured from clay or metal and lasted 8 to 9 hours. In the early 70s, Frank Nasworthy introduced the urethane wheel to the sidewalk surfing world. This new smooth riding wheel propelled the sport into modern day skateboarding. As the sport progressed new wheels were being created for different styles of skating. Adjusting the recipe for urethane can change wheel properties, like durometer, which you can use to optimize your ride. Just what is urethane? And what exactly is changed to adjust the properties of a wheel?
Zelda Ziegler, Professor of Chemistry at the Central Oregon Community College, sat down with me to discuss urethane wheels on a molecular level. Because each wheel company uses unique formulas, we were unsure where to start. However, there are some things common to all urethane polymers. All polymers are made by repeating two different types of small molecules which she represented as A and B. In poly-urethanes they alternate ABABABABA..ect. for many repeating units. The A side provides half of the urethane link and the B side provides the other. Each A and B have at least two connecting points on the molecule. The connections on the A molecules are called isocyanate groups. The connections on the B side can be many different things, but are usually alcohol groups. When you put all the A's and B's together, they easily connect together to form extremely long chains with freshly made urethane linkages. When you have molecules this long and flexible, they form elastic solids.
Many thanks to Zelda Ziegler, Professor of Chemistry at the Central Oregon Community College.