A humdinger of a trail wheel.
With the abundance of mid-travel 29-inch trail bikes on the market, we're thankful for excellent rolling stock options like Mavic's XA Elite 29 Boost Wheel when building up a new trail machine or upgrading existing wheels. The rim's 25mm internal width does an excellent job plumping up modern trail rubber with a good deal of air volume. More volume allows for lower PSI, which in use, provides more traction, better bump absorption, and less rolling resistance. The generous rim width combines with the wide Boost hubs, which helps improve the spoke bracing angle providing better overall wheel stiffness and eliminates the initial complaints of larger diameter wheels.
And while we've come to appreciate wider internal widths and large diameter wheels, we also value lightweight, stiffness, and durability and thanks to Mavic's ISM 4D method of extruding and machining the rim, it's able to remove extra material with zero tradeoffs. Now in its 4th iteration, the milling is more rounded off versus the squared off machining of previous versions. The milling is strategic in that it only removes superfluous material so it ensures that the rim doesn't lose stiffness or strength while also looking pretty trick in the process.
The XA Elite's rim also sees a loss of material on the inside, notably where Mavic eliminated the bead hook with its latest update to the Universal Standard Tubeless (UST) tire bed design. UST first surfaced in the late '90s, as a collaborative effort between fellow Frenchies Michelin and Hutchinson to eradicate the world of tubes. Mavic was a bit ahead of the curve with this one and it took almost a decade before it gained the widespread acceptance it enjoys today.
It took us a second to wrap our heads around just how a tire stays on the rim without a bead hook, however, bikes are one of the only vehicles that use bead hooks to begin with, so eliminating them isn't as extreme as one would expect. Modern tire beads are strong and don't stretch, or if they do, it's very minimal. That conspires with a special channel in the rim bed and specially designed bead shoulders that help lock the tire into place when inflated. In the end, Mavic's hookless UST design reduces burping, provides a more natural tire profile when inflated, and it makes installation easier.
The rims are laced to Mavic's own hubs where the rear freehub features two pairs of pawls that are phased to improve engagement while reducing drag. Quicker engagement means less lag between pedal input and forward motion, quite helpful when negotiating a tricky technical section or getting back on the gas quickly and accelerating out of a berm.
- Mavic's alloy mountain offering for 29ers
- 25mm internal width pairs well with modern trail tires
- Hookless bead creates an ideal tire and rim interface
- Boost axle spacing provides a better bracing angle for stiffness
- ISM 4D milling process mills away unnecessary material saving grams
- Two sets of phased pawls cut engagement time in half