Year after year we have been riding in cold Minnesota winters with SPD compatible footwear. We learned years ago that a cold metal cleat right under your toes makes it difficult to keep your feet warm when the temperature dips below freezing. It is amazing how a small little piece of metal can suck so much heat away from your foot without the right insulating gear. In addition, there is the challenge of maintaining insulation value in the small space between your foot and the cleat. There is very little room to create lofted air space to trap what little heat is generated by the extremeties of the body (foot arch and toes). To make matters even more challenging, we needed to consider that pedaling force tries to compress anything that is between the foot and the cleat, jeopardizing the limited air space required by most insulation materials. While designing the Wölvhammer, we set out to solve this problem.
How did we solve these design challenges?
Aerogel. Aerogel has been used by NASA and the space industry to protect astronauts and sensitive equipment from the temperature extremes of outer space. It is lightweight, protects against heat AND cold, and has the highest insulation value (CLO) of any insulation that exists. These three key characteristics made aerogel an ideal insulation material for space-age equipment.
It is a nanoporous solid created when silica is gelled into a solvent, and the solvent is extracted to create a puffy sand-like substance with 99% porosity. Porosity creates air gaps, and in the case of aerogel, these gaps are so small that they slow the transport of temperature, resulting in record-low thermal conductivity. Aerogel is laminated inside of custom die cut panels so the technology can be applied to softgoods, including 45North Jaztronaut insoles.
Compression and Insulation
Aerogel is an ideal solution for softgoods that require insulation in areas where there is compression. Lofted insulation such as down fill loses its ability to insulate well when it is compressed. Aerogel is a non-compressible insulation, which means that it still insulates when you're stepping on it or pedaling at 400 watts! This is why we chose aerogel to put between your foot and that cold metal cleat. The chart below illustrates how aerogel maintains its R-Value (thermal resistance) as pressure is applied to it. R-Value remains constant while pressure increases.
Jaztronaut Insole Construction
45North Jaztronaut insoles are constructed by laminating 2mm of aerogel between two layers of EVA foam. The bottom layer of foam has a higher density for durability, while the top layer is softer to provide comfort on the bottom of your foot. Jaztronauts were specifically designed for the Wölvhammer boot, but the shape and cut of the insoles is compatible with most other road and mountain cycling footwear. They are available in six trimmable sizes ranging from size 38 to 50. For example, the size 46-47 insole will fit inside a size 47 shoe without trimming. To put it inside a size 46 shoe you just need to trim along the line on the toe as illustrated below.
The snow is already falling in Minnesota, and Jaztronauts are available now from your local dealer. See below for part numbers and size breakdown information.
SH4513 - sizes 38/39
SH4514 - sizes 40/41
SH4515 - sizes 42/43
SH4516 - sizes 44/45
SH4517 - sizes 46/47
SH4518 - sizes 48/49/50