Rear wheels absorb punishment that front wheels never see: repeated torque spikes from hard accelerations, sustained wattage on long climbs, and the combined forces of pedaling and braking through every corner. The Mavic Cosmic S 42 Disc Carbon Rear Wheel addresses these demands with a 100% carbon fiber rim paired to an aluminum hub body built around Mavic's Instant Drive 360 freewheel. The quick-engagement mechanism transforms pedal input into forward motion without the lag that lesser hubs introduce, using a contactless rubber seal that reduces friction while maintaining durability over thousands of miles.

The 42mm carbon rim shares the same wind-tunnel-developed profile and flat spoke design as its front counterpart, providing aerodynamic consistency across the wheelset. At 885 grams, the rear wheel contributes to a 1660-gram pair weight that balances climbing performance with aerodynamic efficiency on flatter terrain. The 21mm internal width supports modern tire volumes, allowing wider rubber to assume a rounder profile that improves cornering grip and permits lower pressures without sacrificing rolling efficiency. Mavic's UST tubeless system arrives ready with rim tape pre-installed and a valve included, simplifying setup while delivering the comfort and puncture protection benefits that tubeless provides.

The aluminum hub body houses QRM Auto bearings, Mavic's sealed cartridge system with automatic preload adjustment that maintains smooth rotation without developing play over time. This design eliminates the periodic maintenance that conventional hubs require while handling the torque loads that disc brakes and hard efforts place on rear wheel bearings. The bearings feature double seals and C3 internal clearance, providing long-term reliability regardless of weather conditions. Center Lock mounting accepts standard rotors, and the disc-specific construction manages braking forces without compromising the hub shell.... Read More