The SIDI Heel Cup is an external, reinforced cup that stabilizes and supports the heel, with an By 1988, clipless road pedals had become the norm, and this presented a new problem—shoe closures were put under tremendous strain, as a pedal stroke’s upward pull had to be entirely absorbed by the shoe without the additional support of a toe strap.
Dino Signori’s solution was as revolutionary as it was genius: In 1989, he introduced the first ratcheting buckle closure for cycling shoes, combining the robust holding power and on-the-fly adjustability of toe straps with the strength to withstand the powerful, repetitive pedal stroke of professional racers. It was the SIDI Micro Lock, the first micro-ratcheting buckle.
The current Caliper Buckle is the latest incarnation of SIDI’s famed ratcheting shoe closure. It ratchets in both directions, allowing for precise, incremental tightening and loosening of the closure, for easy on-the-fly microadjustment. Pulling upward on the lower lever tightens the strap, click by click; pressing down on the upper lever loosens it a step at a time; an outward pull on both side levers completely releases the buckle.
Caliper buckles may be retrofitted to older SIDIs, as long as the ratcheting strap is also replaced by the matching Caliper Strap (which fits older versions of the Soft Instep Closure System®).