Machine Design

Hit me with your best rock

During the Hammer Fest downhill mountain bike event on Vancouver Island last Spring, pro rider Dharma Fontaine hit a rock that flattened his rear tire early in the race.

At the finish line, I checked the FRX5 bike wheel from Tag Wheels, Newport Beach, Calif. expecting to find massive damage, says Fontaine. "But unlike traditional wire spoke wheels that would see permanent rim damage from such a severe impact, the single piece FRX5 wheel made from Zytel nylon only had a small insignificant ding beneath the destroyed tire."

To make its innovative new wheel, Tag Wheels used a toughened, glass-reinforced 8018 grade of Zytel nylon from DuPont, Wilmington Del. "Extensive testing in the lab and in the field, shows that this material gives us just the right combination of impact resistance, strength, stiffness, and moldability," says George Kotzeff, president of Tag Wheels.

The one-piece design optimizes structural strength, impact resistance and functionality. Wall sections vary in thickness to provide additional strength and stiffness where needed. Each spoke has an internal rib. The hub shell is a robust, thick-walled construction, and it is keyed to improve shear resistance and torque transfer, according to Kotzeff. The design minimizes pinch flats with a relatively thick, flat-topped bead and a resilient rim. The rear wheel has an integral chain-catcher feature to combat chain binding.

The FRX5 wheels are made using a patented lost-core molding process that makes possible its complex geometry and strong hollow structure. The process starts with molding a metal mandrel from a low-melt-point alloy. This mandrel is then over-molded with Zytel 8018. The mandrel, or core, is then melted out leaving behind the hollow-formed composite wheel. FRX5 composite wheels come with high-quality DT Swiss 440 hubs.

More information:
Tag Wheels
DuPont Zytel

Advantages of the FRX5 Zytel nylon wheels over traditional wire spoke wheels include fewer flats, reduced flat spots and less maintenance. They also won’t need truing, tension or alignment procedures.

TAGS: Archive
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.