Zipp 840 Rim Brake Disc Wheel 650c

The Zipp 840 Rim Brake Disc Wheel 650c is Zipp's purpose-built solid carbon disc wheel for 650c triathlon and time trial setups. Zipp introduced its first disc wheel in 1988, making it one of the original pioneers of carbon disc technology in the sport, and the 840 carries that pedigree forward in 650c form. The 840 is the 650c counterpart to Zipp's 900 — the same proven disc platform in 650c dimensions, built for the smaller wheel configurations that have long defined serious multi-sport racing.

The 650c sizing is purposeful, not incidental. Dedicated triathlon frames are often designed around 650c wheels — particularly on the front axle — to optimize the aerodynamic envelope of the rider's position, lower the front end geometry, and reduce the gyroscopic forces that affect handling at speed. A smaller-diameter front wheel allows frame designers to shrink the fork and headtube, pulling the wheel closer to the rider's legs and creating a cleaner overall profile. On technical courses where direction changes matter, the reduced wheel diameter also improves steering response. The 840 delivers the full disc advantage at 650c for athletes running this configuration — the same unbroken aerodynamic surface, at a size matched to frames designed around it.

The 840 is a true solid disc wheel — no spokes, no nipples, no spoke tension to manage over a season of racing and training. The carbon composite construction is finished with a dimpled surface, Zipp's patented treatment applied to the entire face of the disc. Those dimples create micro-turbulence across the carbon surface that delays flow separation from the boundary layer, allowing air to remain attached to the disc face longer before breaking away. The effect is aerodynamically meaningful in the yaw conditions that riders encounter in real race situations, where wind rarely arrives perfectly head-on. Zipp applies this dimpling principle across its wheel lineup, and on a solid disc — where the entire face is one uninterrupted aerodynamic surface — the treatment has the maximum surface area to work with.

Braking is via a machined rim brake track on the carbon surface — this is a rim brake wheel, compatible with standard road caliper brakes, not hydraulic disc calipers. The rim brake configuration fits cleanly on dedicated TT and tri bikes where rim caliper setups remain the standard. The wheel uses a Zipp 182 disc hub, the combination road/track hub that has anchored Zipp's disc program for decades. The 182 hub includes a track axle conversion kit, making the 840 functional as both a quick release road wheel and a fixed-gear track setup. Cassette compatibility covers Shimano and SRAM 10-speed systems. Tires mount tubular — the preferred format for serious TT and tri competition, where the lower rolling resistance and the option to continue riding on a flat outweigh the setup complexity of clincher or tubeless systems.

The Zipp 840 is a specific tool for a specific rider: tri athletes competing on 650c-equipped bikes who want Zipp's full-disc aerodynamics, time trialists building custom wheel configurations around smaller wheel sizes, and track riders who need a proven road disc that converts for fixed-gear use. It's not a training wheel or an all-rounder — the tubular tire bed and rim brake track make it most at home at events where setup is part of the game plan. Within that context, the 840 delivers the aerodynamic advantage that defines Zipp's disc wheel program: a clean, unbroken carbon face from hub to rim, built on over three decades of competition-tested disc technology. Available in white decal graphics with Shimano/SRAM 10-speed cassette compatibility.