The Sidi women's T-4 Air Carbon Composite Shoes are built with a host of features designed to transform your transitions. The opening allows for easy entry and exit, and the tri-specific enclosure design makes adjustments mindless enough that you can focus on dodging sloughed-off wetsuits and other athletes lurching to wobbling starts as you exit T1. Once on the road, the women-specific last provides a more race-worthy fit for athletes with more petite feet -- after all, you've already cleared the swim leg; no need to make your feet swim in their shoes. From a purely functional standpoint, we can agree that rigidity is key. That's why Sidi uses a multi-step system to reduce the dissipation of your power output in the shoe/pedal interaction. To achieve this, Sidi incorporated its new Twelve Carbon Composite sole, a carbon-reinforced nylon matrix that delivers stiff power transfer with long-mile comfort and durability. Sidi estimates that the new material is less susceptible to temperature extremes and wear than traditional nylon models, so the soles are predicted to retain their rigidity over multiple seasons of use. For fit, Sidi understands that triathlon plays by another set of rules. The brand's hallmark ratcheting system and Ergo Buckles aren't relevant to your discipline, so Sidi incorporates a two-strap closure system mated with a 'burrito-wrap' upper, with one layer of the upper wrapping over the other. This allows you to quickly dial in the volume of the shoe while rolling out of T1. The large top strap opens away from the drivetrain to allow a quick and seamless securing of the shoes from the saddle. As for the bottom strap, you'll find that this is used less for transitions and more left alone once you've established your desired volume and fit. However, the gripper tabs placement on the strap simplifies any adjustments that you might need to make while on course. For extra time savings at T1, Sidi has also included a durable pull-tab at the heel.