The midsole, sandwiched between the sole and the upper, is the hidden component in boot manufacture. In many ways it is the "engine room" of a boot and one of the most important components.
Because it is hidden, some manufacturers make great compromises in the midsole in order to make the boot more instantly comfortable and cheaper. This is a shortcut in production that will later be paid for in the performance of the boot. Unlike many manufacturers, SCARPA uses several midsoles in its footwear range - the choice being dictated by the end-use requirements of the boot. Each one of these midsoles is graded to offer differential flex characteristics down the length of the boot whilst giving maximum lateral support. The midsoles are also graded by size to ensure constant performance characteristics in each boot size. The method by which midsoles are attached to the upper is critical to the performance and durability of the boot. Most manufacturers simply bond or staple the midsole. SCARPA "Blake" sew the upper and midsole together on all their hill and mountain boots. Not only does this improve the strength of the boot but it is critical if ever the boot is to be resoled. The stiffness of the midsole is a critical factor if you plan to use crampons with your boots.
A midsole with generous flex down its length but offering good lateral support. Featured in the walking boot range it not only provides good support for walking, but is also instantly comfortable and requires virtually no breaking in. Can be Poly propelene, Nylon or Texon material dependant on model.
Using nylon for its permanent performance qualities, the comfort flex midsole is moulded so it has minimum flex in the heel section but gives comfortable flex in the forefoot area. It is used for walking and hillwalking footwear.
This is a more robust, nylon midsole giving superb support to the whole foot. Its graded design provides a perfect balance between longitudinal flex and total lateral support for walking on rough ground or steep hillsides. Performance flex is used in the top performance hill and mountain walking boots. It requires a short amount of breaking-in but supports and protects the sole from the tiring effect of walking on hard or rocky surfaces. Boots with this midsole can be used with flexible walking crampons.
Used in serious mountain walking and scrambling boots, this unit is stiffer than Performance flex. Whilst it retains some longitudinal flex for walking comfort, its extra stiffness is designed to give total underfoot support. Pro-flex is used in serious mountain boots where crampons may be used.
Used for serious mountaineering, scrambling and climbing. This midsole retains a small degree of longitudinal flex for comfort during walk-in's and serious mountain walks.
Used in fully stiffened boots, with sustained front pointing in mind, this heavy duty nylon midsole is further supported with an integral shank for maximum underfoot support.
Used in the Rebel Ultra GTX and the Rebel Carbon GTX, provides a fully rigid, torsionally stiff, lightweight yet immensely strong mid sole.