Reynolds Blacklabel 349 29 Boost Wheelset

The Reynolds Blacklabel 349 29 Boost Wheelset is Reynolds’ wide-trail carbon wheel — built for riders who push into technical terrain, run high-volume tires, and need a rim that can handle what aggressive trail riding actually demands. The “349” name tells you exactly what you’re getting: 34mm of internal width in a 29-inch wheel. That’s a meaningful step up from the narrower trail rims that came before, and it changes how the tire behaves in corners, how the sidewalls hold up under load, and how the whole contact patch communicates with the ground beneath you. Built on the same Blacklabel platform as Reynolds’ downhill and XC wheels, the 349 carries the brand’s full performance credentials into a wide-trail package on standard Boost (148mm) rear spacing.

Rim construction starts with Reynolds’ MR5 carbon layup and IDM — Impact Dispersing Matrix — the same resin and carbon fiber combination Reynolds developed for its World Cup downhill wheels. At 34mm internal and 39mm external width, these are wide rims by any measure, and IDM is what makes that width viable on a trail wheel rather than a liability. Wider rims absorb impacts differently than narrow ones — there’s more material in the strike zone — and IDM’s impact-dispersing characteristics give the 349 a level of rim durability that the weight figure alone wouldn’t suggest. The 25mm depth keeps the profile low enough to preserve ride compliance, a deliberate decision: running a wide rim at a shallow depth maintains the vertical flex that makes the wheel feel planted rather than harsh. Both wheels come pre-taped with tubeless valves installed, hookless bead, and are ready to mount a tubeless tire without additional setup.

The hub spec is consistent with the rest of the Blacklabel lineup: Reynolds’ proprietary CNC-machined shell built around Industry Nine Hydra internals, delivering 0.52° of engagement. On steep, technical trail riding where you’re often in a near-stopped, low-speed balance, that engagement translates directly to confidence — there’s no searching for power, no micro-delay between the pedal stroke and the wheel moving. Both wheels run 28 Sapim CX-Ray bladed spokes with alloy nipples, a uniform lacing pattern that balances weight and durability evenly front to rear. The wheelset is Center Lock disc only and comes in three freehub configurations — Microspline, Shimano, and XD Driver — covering every major drivetrain standard. The rims carry a lifetime warranty.

Design Benefits

1. 34mm Internal Width — Built for Wide Trail Tires — The 349’s rim width supports high-volume trail tires the way they’re meant to be ridden: with a fuller tire profile, better cornering support, and a wider contact patch that holds traction in loose and rough conditions. Running a 2.4” or wider tire on a 34mm rim makes a tangible difference in how the tire behaves.
2. IDM Carbon — Downhill-Derived Rim Durability — Reynolds’ Impact Dispersing Matrix resin system was built for World Cup downhill punishment and applied directly to the 349. The result is a wide-profile carbon rim that can take rock strikes and hard trail landings without the fragility concerns that sometimes accompany light carbon wheels.
3. 25mm Depth for Trail Compliance — The shallow rim profile is intentional. A wider rim at low depth preserves vertical compliance, keeping the wheel from feeling harsh and transmitting too much trail chatter. The 349 is designed to feel planted and controlled, not stiff and punishing.
4. Industry Nine Hydra Internals — 0.52° Engagement — Instant hub engagement means instant traction. Whether you’re crawling through a tech section or sprinting out of a corner, the I9 Hydra internals eliminate the delay between effort and output — a practical advantage on unpredictable terrain.
5. Sapim CX-Ray Spokes, 28 Per Wheel — Uniform 28-spoke lacing front and rear keeps the build consistent and predictable. CX-Ray bladed spokes are among the strongest and most fatigue-resistant available, well-suited to the lateral loads and impact events that trail riding generates.
6. Boost 148mm Rear Spacing — Standard Boost compatibility means the 349 drops straight into the widest range of modern trail, all-mountain, and enduro bikes without adapters or modification.

Final Take

The Reynolds Blacklabel 349 is a wide-trail carbon wheelset that earns its price through construction quality, not just brand cachet. The 34mm internal width, IDM carbon rims, and I9 Hydra hubs are a coherent package built around one goal: giving trail and all-mountain riders a wheel that performs at the limits of the terrain without asking for careful handling in return. If you’re running aggressive trail tires and pushing into rough ground, the 349 is the Reynolds wheel for that kind of riding.