The Industry Nine Deal AL rear wheel pairs a Dynamal aluminum alloy with Hollow Bead Wall construction to stand up to downhill's biggest hits. The magnesium-silicone hardened alloy adds tensile strength and stiffness beyond a standard extrusion, so the rim holds its shape through square-edge impacts and hard braking bumps. What Our Gearhead(R) Experts Are Saying:"Every ratchet click from the Hydra2 System hub lands the same way, run after run, so I never second-guess a pedal stroke coming out of a rock garden. That kind of consistency at 870 points of engagement is what lets me commit to a line instead of hesitating."