Composite Runner FAQ

1. What is a wood core composite?
   

   In their simplest form, composite materials are composed of reinforcment material and a resin binder. A fiberglass bathub is an example of this type of composite. Core materials are used where greater thickness is desired, or to create a high strength stressed skin structure. Some boat hulls are made this way, as are most composite aircraft parts. We have chosen to use wood as the core material for a number of reasons.

2. Why don't you use glass fiber?
   

   Glass fiber has a much lower strength to weight ratio than either carbon fiber or Kevlar^®, and relatively poor low temperature performance.

3. Why carbon fiber and Kevlar^®?
   

   Carbon fiber has very high stiffness and tensile strength, but is weaker in compression, has low impact resistance, and poor vibration damping. Kevlar^® has good compressive strength, high impact resistance, and excellent vibration damping. In other words, the strengths of the two different materials complement each other nicely. When properly used in combination, they produce a set of physical properties which cannot be matched by any single material.

4. Why do you use epoxy instead of the less expensive polyester or vinyl ester resins?
   

   Both polyester and vinyl ester resins have poor low temperature performance. Epoxy is the resin of choice for the most demanding composite applications. Dogsleds are routinely exposed to high stresses and impact loads at low temperatures. The manufacturer of the resins used in CB Sled composite runners states:

   "Extensive fatigue testing and infield use have demonstrated that (our) epoxies produce lightweight structures with an exceptional ability to withstand cyclic loading in harsh environments."

5. What are the "state of the art manufacturing techniques"?
   

   To quote Kjetil Backen; "I won't tell you." They are trade secrets. Research and development work in both materials and processes started several years ago and is ongoing. The processes require specialized materials, knowledge, facilities and equipment. "Don't try this at home."

6. What does "flex pattern including progressive flex in the trailing runner" mean?
   

   "Flex pattern" means that the stiffness of the runner can vary over its length. "Progressive flex in the trailing runner" means that the runner gets progressively more flexible towards the tail. This gives a smooth ride and enhances handling. It works for skis, and it works for sled runners. Monolithic runners can not provide progressive flex.

7. What are camber and rocker and why would I want one or the other?
   

   Runners with camber are bent downward toward the tail. Runners with rocker are bent upward toward the tail. Camber distributes the driver's weight more evenly and improves stability. Rocker makes the sled more responsive but decreases stability. Which and how much you would want depends on the intended primary use.

8. You say that they are strong, does that mean that they are stiff?
   

   NO! When using composite construction, strength and stiffness can be controlled independently. If you want them stiff, we will make them stiff, if you don't, we won't. They are strong either way.

9. How much do they weigh?
   

   That depends on their size and construction, of course, but CB Sled composite runners typically weigh between 5 and 7 lbs per pair.

10. How much do they cost?

As above, that depends on their size and construction, but usually between $25.00 and $30.00 per foot.