Of all the hoops that 29ers have been forced to jump through in order to prove their worth to industry nay sayers, wheel stiffness remains the last meaningful objection. The Mercury Wheels X1 Carbon 29in Wheelset puts that complaint to bed, clearing that final hoop courtesy of its responsively stiff carbon hoops. And while they're responsive as hell on climbs, the rims really shine while tracking across terrain. Loose, chundery, crunchy it doesn't matter the X1 Carbon goes where you point it without hesitation. The rims are so stiff that Mercury is able to reduce weight by reducing the spoke count from the usual all mountain staple of 32 to just 28 per wheel. While the spokes' two cross pattern further increases lateral stiffness for more efficient climbing and tenacious tracking, their reduced number provides a touch of radial flex for more forgiveness on big hits. Of course, carbon rims are still obscenely stiff, which is one reason why we aren't sorry to trade the additional and unnecessary stiffness of a 32 spoke build for the lower weight of 28 spokes. The other reason is that fewer spoke holes mean less drilling and, ultimately, a more structurally sound rim. The rims are built with a hookless bead, which contrary to what common sense might suggest makes the rim to tire bead connection more reliable. Burping and tire blow offs are actually more common with hooked rims, and the hookless models also demonstrate improved tire retention on trail. By eliminating the ridge of material constituting the hook, hookless beads also enjoy increased structural integrity a definite plus when you consider that the X1 Carbon is built for the big hits of enduro and all mountain riding. We have found that mounting some tire brands can be a little tricky, but once they're on the bead holds a tubeless setup as steady as any other manufacturer's. Finally, note that the rims don't include tape or tubeless valves, but we've had luck installing most readily avai.