Synthesis Gravel brings Crankbrothers' tuned wheel thinking to drop-bar bikes: a wide, shallow carbon rim that absorbs trail feedback for a smoother, more comfortable ride on long days and rough roads. This is the 650B rear wheel with a XDR freehub body.

Highlights

• Carbon rim with a shallow, compliant 21mm profile
• 26.5mm internal width, optimised for 40–48mm gravel tyres (rated for 30–55mm)
• Synthesis Ratchet hub with 10° engagement
• XDR freehub body, 142x12mm thru-axle and Centre Lock rotor mount
• 28 Sapim D-Light spokes
• Tubeless ready, with the rim backed by Crankbrothers' lifetime warranty

Built for comfort on rough roads

Crankbrothers tunes the Synthesis Gravel rim to deflect under side loads and vertical impacts, which it says improves handling through turns and smooths out the ride, keeping you fresher for longer. The 26.5mm internal width supports high-volume gravel tyres, giving a bigger contact patch for grip in corners while adding sidewall stability.

Synthesis Ratchet hub

The ratchet-style drive gives 10° of engagement without excess drag, according to Crankbrothers. For quicker pickup, the brand's 54T Ratchet Upgrade Kit (sold separately) suits Synthesis wheels already fitted with a ratchet system and brings engagement to 6.6°.

Compatibility & fit

Rear wheel only: Crankbrothers sells Synthesis Gravel wheels individually, not in sets. It suits 650B gravel frames with 142x12mm thru-axle spacing and Centre Lock rotors. The XDR freehub body is road-length; Crankbrothers says it can be adapted for MTB cassette spacing with a 1.85mm spacer, and recommends confirming cassette fit with your drivetrain maker. Ratchet freehub bodies are also available separately in Shimano HG, HG Road, Micro Spline, SRAM XD and XDR. Crankbrothers lists this wheel as not e-bike compatible. Add your own cassette, Centre Lock rotor and tyre; our workshop can fit them or swap the freehub body as a separate service.