Shimano rebuilt the all-rounder in its wheel range from the layup outward. The DURA-ACE WH-R9370-C50-TL keeps the 50mm depth that made the outgoing generation a default race choice, but a revised carbon rim layup, new hub architecture, and carbon spokes bring the pair to 1302 grams, 159 grams under the WH-R9270-C50 it replaces. That figure does its work on climbs and in the repeated accelerations that precede them, which is where an all-round wheelset spends most of its race day.

The rim profile was drawn around current tire sizes rather than adapted to them. Internal width measures 23mm, sized for 28 to 30C rubber, with external widths of 31mm at the front and 32mm at the rear. Shimano ran more than 5.4 million shape simulations before validating the results in the wind tunnel, arriving at a profile it rates as a 6% aerodynamic improvement over the previous C50, with drag reduced by up to 2.7 watts in testing at 48km/h on 30C tires.

Carbon spokes carry most of the structural argument. The C50 uses the Aero profile, 4.0mm wide and 1.1mm thick, laced 21 front and 21 rear. Shimano took the design through two testing phases with WorldTour riders and professional triathletes, and settled on a spoke package that holds lateral stiffness at race speeds while retaining a measure of flex the engineers credit for responsiveness on real roads rather than on a test rig.... Read More