3T Discus Plus I28 LTD Tubeless Wheelset

The 3T Discus Plus I28 LTD Tubeless Wheelset is 3T's gravel-specific 650b carbon wheelset, built around a design philosophy that challenges the default. Most gravel wheels are 700c. 3T's position — the one behind both this wheel and the Exploro gravel bike it was designed to pair with — is that 650b offers a more compelling set of trade-offs for riders who want to run wider tires on challenging terrain without compromising how their bike handles.

The argument is geometric. A 650b wheel with a 47mm tire has the same overall diameter as a 700c wheel with a 28mm road tire. Same diameter, but roughly three times the air volume, traction, and compliance. Run a 54mm tire on the same 650b rim and the overall diameter still only matches a 700c wheel with a 40mm tire — with nearly four times the air volume of a standard road setup. The practical consequence is that 650b lets you run significantly wider tires without the cascading geometry changes that force a bike to grow: longer chainstays, longer front-center, slower steering, taller headtubes on smaller frame sizes. The Discus Plus I28 LTD is the wheel that makes that argument in hardware.

The I28 designation refers to the rim's 28mm internal width — considerably wider than the 19mm standard found on most road and gravel wheelsets. For 47–60mm tire widths, a 28mm internal width reduces lateral tire flex in cornering, making handling more predictable on loose or technical surfaces. The wider bead seat also enables lower running pressures without the tire rolling off under load. The rim uses a hookless bead design — the appropriate choice for gravel tire widths where road-style hooked beads aren't required — which keeps the rim profile clean and tubeless mounting straightforward.

Construction is 100% unidirectional carbon in an ultralight layup, 30mm deep and 33.4mm wide externally. The rim bed uses angle-specific spoke drilling to align the nipple seat with the spoke's pull angle, reducing stress concentration at the rim wall. At 1,508g for the pair, it's competitive for a full-carbon 650b disc wheelset. Spokes are Sapim D-Light straight-pull, stainless steel with a black finish, 24 front and 24 rear. Nipples are Sapim Polyax 14G brass in a black finish — brass holds up against tubeless sealants significantly better than alloy nipples, which can corrode and seize over time. 3T explicitly recommends avoiding alkaline sealants with ammonia or sodium for best long-term nipple durability.

Hubs are 3T's GW Bombproof units with oversized light alloy bodies in a black satin anodized finish, running a Syntace X-12 axle standard — 100×12mm front, 142×12mm rear with 1.0mm thread — on centerlock disc mounts. Bearings are adjustable rather than cartridge, allowing preload to be tuned over time. The Sealtight system uses contact-style seals rather than the contactless labyrinth designs common on many hubs. Contact seals feel noticeably stiffer when new and require 100–1,000km of riding to fully settle in. 3T is upfront about this: a wheel that spins endlessly straight out of the box typically has seals that don't make proper contact, which means they're not keeping mud, water, and grit out of the bearings where it matters.

The wheelset ships with both freehub bodies included — a SRAM XD-R body compatible with both XD and XD-R cassettes, and a Shimano body for 10 and 11-speed cassettes. Most carbon wheelsets at this price require a separate freehub purchase to change drivetrain standards. The Discus Plus I28 LTD ships prepared for either, which means it moves between drivetrain setups without an additional purchase and stays useful through future component changes.

Available in Matte Black. The Discus Plus I28 LTD is purpose-built for riders who have committed to 650b for gravel — running 47mm or wider tires on rough terrain — and want a wheelset designed specifically around that use case rather than adapted from a road or general-purpose gravel platform.