Why Not Polyurethane?

The last few months we've been down a long wandering path in Pocket Rocks development. It's difficult keeping to a release schedule when the design-->prototype-->testing-->repeat cycle is dependent on one main person (me) who is a perfectionist. Since I'm also the main person who runs the company, this gets further complicated when partnering with other companies to implement the design. Development time and uncertainty increase by 10x.  :-(

While I won't bore you with all the details, one of the major side-paths taken in the development of Pocket Rocks was trying to mold them in urethane. Since this is the industry standard for climbing holds in gyms, it makes sense to use urethane, right?! They look really slick, so what's not to like?! Well... what makes good climbing wall holds isn't necessarily the best material for training devices. Here's why I believe urethane is not the optimal material for Pocket Rocks:

• Texture. While many urethane climbing holds offer wonderful texture for climbing walls, that same texture becomes a liability with intensively training on a small range of grip positions. Texture is nice for simulating different rock types in the climbing gym and for actually climbing a route. However for training devices, skin and joint-friendly surfaces are more important. They may not offer as much friction, but the purpose of training isn’t to make it easy, right?!
• Weight: For portable training devices, wood can be significantly lighter depending upon what type of wood is used. A set of equivalent urethane grips can be almost twice as heavy. For portability wood makes more sense.
• Efficiency: Urethane relies on silicone molds that have a very limited lifespan and degrade with use. New molds have to constantly be made from a physical master, which is both labor and material intensive. The design for wood grips is stored electronically as a CAD drawing file and each grip is precision machined with no degradation or deviation over time. Each one is always the same. It’s also much easier to make design modifications.
• Longevity: The wonderful texture of urethane holds wears under intensive use, and once it's smooth and polished, there’s no easy way to restore it to its original condition.
• Sustainability: Urethane training devices use non-renewable resources that aren't easily recyclable - at least that I'm aware of. Wood is a renewable resource and is also biodegradable. When used in small quantities and sourced from managed plantations or eco-woods, it doesn't contribute to deforestation. 
• Air bubbles: In two-part molds we ran into issues with air bubbles in the prototypes. I'm not sure if that was due to the unique design of Pocket Rocks or the incompetence of the hold company. :-/
• Labor: Pocket Rocks require a two-part mold for urethane because of their shape. This drives up the cost of labor compared to climbing wall holds, most of which are simple single-sided, easy-pour molds. While cost isn't the final determinant, in combination with the other reasons it is a significant factor. One of our design goals for Pocket Rocks is to offer a lower cost portable training device.

In short, for training devices, look beyond urethane...

CAD rendering of hardwood Pocket Rocks

Stay tuned for news about the release of Pocket Rocks.