SIDI knows that speed and comfort are heavily correlated; if you&';re in pain, chances are you won&';t be moving too quickly. That&';s why SIDI utilizes their proprietary TECNO-3 SYSTEM to optimize the fit along the entire length of the upper. The result? A customized fit. SIDI has further refined their reliable and replaceable closures by introducing an exclusive SIDI Wire material that makes on-the-fly adjustments an absolute breeze. The SIDI SRS FAST sports a reinforced cup that stabilizes and supports your heel. This allows you to convert more power from your pedal stroke to road bike speed. Beneath the heel piece you&';ll find a replaceable heel pad so that you can increase the shoe&';s lifespan with ease. A carbon composite 20 sole composed of nylon and carbon fiber further elongates the life of the shoe to keep the nylon stiff. With an upper designed with a microfiber synthetic leather for real leather feel and outstanding abrasion resistance, you&';ll have an aging resistant anti-bacterial surface that&';ll look fresh long after other competing shoes.