Derby Rims

DERBY CARBON AM WIDE 40/35mm RIMS 27.5”/29”

Derby helped usher in the wide rim revolution by optimizing their rims for tires 2.3" and wider.

If you are a fan of wide MTB tires you will appreciate the stability and handling performance gained when pairing your favorite tires with a wider section rim. A wider rim opens a tires' profile and changes it from a "round" or "lightbulb" shape toward a "square" shape by widening the base of the tire at the bead. This change in profile can dramatically improve traction and stability.


Derby Rims Carbon AM 27.5 and 29" x 40mm (35mm ID) Wide: Derby Rims have a bead seat retention ridge next to the deep channel around both tire-centering, tubeless ready bead seats. Much like UST bead seat design, the raised bead seat ridges prevents a tubeless tire bead from sliding into the deep center channel and burping while hard cornering. Also the bead retention ridges secure the bead on the bead seat when the tire goes flat, so the flat tire can protect the rim from rock damage while rolling to a stop after flatting. The hookless bead wall with bead seat retention has been used in motorcycle and car tires for decades, but never produced in bicycle rims design before Derby Rims.


    • 29er x 35mm
      • 485g
      • BSD: 622mm
      • Outer width: 35mm
      • Inner width: 29mm
      • ERD: 582mm
      • 32H
    • 650b x 40mm
      • 465g
      • BSD: 584mm
      • Outer width: 40mm
      • Inner width: 34mm
      • ERD: 542mm
      • 32H

    Going to wider rims, the tire's circumference doesn't grow taller. They've closely measured rollout circumference which calculates to tire height, and measured knob width too. Using the same 2.3 Pacenti neo-moto tire on a 650b x 40mm Derby Rims compared to a 28mm Blunt, the tire doesn't grow taller, the tire is no higher at the center knobs, and the edge knobs are actually a very small measurement narrower, about 0.0225 inch or 0.6 mm narrower. But the edge knobs do "stand up" a little higher making a more "square" tread profile, and these edge knobs do come closer to the arch of a fork or yoke of a chain-stay by about 1.5mm, so it is slightly closer clearance above the edge knobs.

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