The Reserve 30XC rim widens to 30mm inside and 37mm outside, so tire sidewalls line up straight from the bead instead of ballooning past it, adding support and grip through rocky, technical sections. Squared-off reinforcement surrounds each spoke hole, a shape Reserve traced back to lab testing to spread load exactly where a 28-hole drilling puts the most stress. What Our Gearhead(R) Experts Are Saying:"I built up a wheel with this 28-hole rim expecting to feel the extra spokes as dead weight, and instead the wheel tracked straighter through braking bumps without any noticeable weight penalty. The stiffness comes from the bracing angles working together, not from a heavier rim to begin with."