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Shimano joins the age of broad aero wheels with new versions of the C50 and C75.
Japanese component giant Shimano isn’t known for quickly developing products, but when an item passes through the engineering department, it is almost always ready for the big time. Many wheel companies have developed aero wheels with wide rims based on the design pioneered by Hed Cycling and Zipp, but Shimano has lagged behind, until now. The deepest wheels they currently offer top out at 50mm—short by today’s standards—and they have an outdated narrow, straight-walled rim design. Pro athletes had access to the C75, a 75mm carbon tubular wheel, but that product was never available to regular riders. After a fairly long wait, Shimano has solved all of those problems.
Craig Alexander broke the course record at the Ironman World Championship this past fall riding a prototype Shimano front wheel. It looked like the commercially available C50 wheel, but in reality it was an early version of a wide rim design. Like the one Shimano is announcing today, Alexander’s wheel had a 24mm-wide rim designed to blend smoothly with a tire. Older versions used a narrower rim, which allowed the tire—typically 23mm across—to protrude past the sides of the wheel, which increases aerodynamic drag. Shimano’s new WH-9000-C50-TU (or C50 tubular) is broad enough to conceal the tire. Its sidewalls are parallel, not bowed like the Zipp’s Firecrest design, and they taper close to the spoke bed to a fairly sharp inner edge. Shimano altered its outstanding hubs to increase lateral stiffness and durability. Most rear wheels distribute the spoke tension unevenly, putting more pressure through the drive-side spokes than the non-drive. The new C50 and C75 (WH-9000-C75-TU) wheels have twice as many drive spokes, which allows for equal tension through both sides of the wheel and improves durability and lateral stiffness. Broader hub flanges create a more obtuse spoke bracing angle to further bolster their side-to-side resiliency.
Like all Shimano products, these wheels are sure to be dependable and durable, but the new rim is the real advancement over the older wheels, which had been left behind aerodynamically. These rims bring Shimano up to par with the rest of the industry in that all-important wheel attribute, but the design isn’t revolutionary. It follows the established designs from other brands, and adds Shimano’s sterling reputation for dependability.
This new rim shape is only available as a tubular wheel. Shimano still isn’t producing a carbon clincher. The aero wheel with a clincher tire—called the WH-9000-C50-CL, or C50-CL for short—retains the aluminum brake track. This rim is 23mm, 2mm broader than its predecessor, which should improve ride quality and aerodynamics by broadening and the tire and blending it with the rim. Other than width, the rim’s profile hasn’t changed dramatically. The carbon section is a tapered V with a moderately blunt inner edge and a small lip between the aluminum and carbon portions. It will sell for $2,400 and the set weighs 1672 grams. The C50 tubular pair weighs 1449 grams and goes for $3,200. The C75 has the same 24mm-wide tire bed and parallel sidewall design as the C50. It weighs 1545 grams and costs $3,500. They will be available for purchase later this summer.