Boost your trail game.
The SRAM Roam 40 27.5in Boost Wheel delivers trail-crushing durability in a lightweight, tubeless-ready package that's up for almost any trail adventure. The Boost axles at the wheels' hearts make for a ride that's noticeably stiffer and more responsive than 100 or 142mm axles. Whether you're out on a weekend trail ride with your friends or bombing an enduro course, the Roam 40 will handle it with ease.
The Roam 40 rim is made from light, strong 6061-T6 Aluminum infused with SRAM's Taper Core design, the result of an extrusion process that allows SRAM to place more material where it's needed for durability. This results in a thinning of the remaining rim profile in order to optimize the balance of weight and strength. In fact, a cross-section of the rim reveals that its main cavity is thinner on the sides than either the bead hook or the spoke bed. The sidewall thins gradually, providing a strong base for the bead hook. This way, the rim is more resistant to denting under hard impacts.
The cross-section of the Roam 40's rim also reveals an asymmetrical shape that offsets the spoke bed, which is key to building the Roam wheels with zero dish while simultaneously maintaining even spoke tension. In a traditional symmetrical rim, the spokes on the drive side must be shorter in order to keep the rim centered relative to the dropouts. Unfortunately, the discrepancy in spoke length puts greater tension on the drive side spokes than the non-drive side spokes reducing the overall strength of the wheel. With an offset rim design, the spoke bed aligns with the hub shell. This keeps both the spoke tension and spoke length equal on both sides, while the shape of the rim centers the tire relative to the dropouts. This lets the Roam wheels maintain correct spacing and reap the benefits of even spoke tension. It's also achieved with identical spoke lengths on both sides of the hub, in both the front and rear. This not only adds strength, but it also means that one replacement spoke is compatible with any side of either the front or rear wheel.
SRAM laces the Roam 40 rim to its Boost Double Time hub, boasting a genius, four-pawl design and a 26t ratchet that pair to magically transform into a whopping 52 points of engagement and durability. The Speedball Bearings come precisely machined and pre-adjusted from the factory with tight tolerances that won't need further adjustment after a day on the trail. The Boost designation refers to the widened axles on the Roam 40 hubs, clocking in at 110mm up front and 248mm in back for an overall increase in wheel stiffness and stability. This translates to better handling out in the dirt for fast, fun times wherever you decide to ride.