Mavic Cosmic SL 40 Rim Brake Wheelset

The Mavic Cosmic SL 40 Rim Brake Wheelset is built for road riders who want full-carbon performance without abandoning their rim brake frames. That's a specific brief, and Mavic takes it seriously — these aren't disc wheels with a brake track attached as an afterthought. The Cosmic SL 40 was engineered from the ground up for rim braking, with a dedicated iTgMax carbon brake track, a 40mm NACA-profile rim tuned for all-around road performance, and an aluminum Infinity hub platform with Instant Drive 360 freehub engagement. The pair weighs 1,600g. At $1,949, this is the current-production carbon rim brake wheel from a brand that has been building Cosmic wheels for over three decades.

The defining technology is iTgMax — Integral Glass Transition Temperature — and it describes both how Mavic constructs and how they finish the brake surface. The inner rim bed is built up with multiple layers of seamless carbon fiber laid in a one-piece contour without cutting fiber runs, a construction method that preserves structural integrity through the brake zone. The brake track is then laser-machined to a precise surface texture designed to shorten stopping distances in both dry and wet conditions. A specific heat treatment process makes this, by Mavic's account, among the most durable carbon rim brake surfaces in production. Each wheel ships with carbon-specific brake pads included. For riders who have dealt with inconsistent heat dissipation or grabby feel from other carbon rim surfaces, the iTgMax track is the reason to consider these wheels specifically.

The rim is 40mm deep with a NACA-inspired profile measuring 19mm internal width and 26mm external. The 40mm depth occupies the all-rounder range: enough to hold speed on flat and rolling terrain without the handling liability that deeper sections introduce on exposed climbs or in crosswinds. The 19mm internal width supports tires from 23mm to 62mm, and the rim bed is UST tubeless-ready — designed to accept Mavic's tubeless setup without the fitment headaches that plagued earlier hookless and deep-bed designs. The new rim bed geometry introduced with this generation was specifically engineered for easier tire mounting and changes. Rim tape comes pre-installed, a UST valve is included, and the wheel arrives ready to run tubeless with sealant. Tube-type clincher tires work equally well.

The hubs run Mavic's Infinity design on aluminum bodies, with QRM Auto self-adjusting bearing preload on double-sealed cartridge bearings with C3 internal clearance. QRM Auto continuously maintains correct preload without manual tuning, which keeps bearing feel consistent over time. The rear freehub uses Instant Drive 360 engagement, built around a large contactless rubber seal to keep friction low while delivering fast pickup when you push out of the saddle. Spoke lacing at the rear follows Mavic's Isopulse pattern — radial on the drive side, crossed two on the non-drive side — a geometry that maximizes drive-side dish and balances spoke tension between the left and right flanges. The front runs fully radial. Spoke count is 18 front and 24 rear, with straight-pull bladed steel spokes and ABS black nipples.

The Cosmic SL 40 runs quick release axles only — 9x100mm front, 9x130mm rear — making it a direct-fit replacement for standard rim brake road hubs. It ships with a Shimano HG road freehub body; optional driver bodies sold separately convert to SRAM XD, Shimano HG Light, Shimano Microspline, or Campagnolo. Maximum supported weight is 120kg including bike. These wheels are designed and engineered at Mavic's facility in Annecy, France, and built by hand in their European carbon factory. For riders on rim brake road bikes who want a wheel built explicitly for that setup — not a converted disc design, not a holdover from a previous generation — the Cosmic SL 40 is a direct answer.