Diadora built the new Sonic Shoes using lightweight, breathable upper materials combined with its tri specific closure. It then mated this to an ultra stiff carbonnylon composite outsole in order to give you a lighweight, affordable package that blends the most important qualities that we look for into a single pair of triathlon shoes. Diadora built the Sonic Shoes around its Regular Plus last. This last shape forms precisely to your foot, combining just the right amount of arch support with forefoot and midfoot hold, but provides a slightly larger toe box than its Race Shape last. Additionally, this design lends itself to securing heel retention as well. The Sonic's microfiber and lightweight mesh upper construction was designed to support pedaling motions with its ultra stable and breathable composition. At the heel cup, Diadora designed the Sonic to perfectly contain the rider's foot in its seat by armoring the delicate Achilles tendon with a two part composition. For structural rigidity, the pre molded thermoplastic polyurethane heel cup uses a firm composite around the back, with softer and more flexible plastics along the sides. The closure system incorporates two separate tri specific straps that each performs specific retention functions. Across the forefoot, Diadora added its V Fit hook and loop strap that allows you to easily control the volume over the forefoot. Moving up from that is the 40mm wide hook and loop strap. This strap's anchor point is positioned on the outside of the foot, allowing you to secure your fit in conjunction with the opposite closing lower strap. The combination of these two straps provides you with the ultimate customizable retention and support. Diadora chose to mate the Sonic's lightweight upper to its Dual sole. This carbon reinforced composite platform keeps stack height and weight to a minimum, while maintaining a high level of rigidity for a direct transmission of power to the pedals. The heel pad is made of a firm re...