Rotor Rex Set

Rotor has successfully brought back the oval chainring with proven science and results. This Spanish company has continued to innovate with incredibly light and stiff cranks mated with their oval rings. For us, the oval rings relieve stress on the knees and hips and increase output, while decreasing pain. In a nutshell, our experience can be summarized as it's "like having a 39 tooth chainring when going over the top of the pedal stroke, but having a 42 tooth ring at the most powerful part of the stroke."

Rotor Narrow Wide Ring

We've found two downsides though and they are:
  • All the other bikes in the fleet with round chainrings feel unnatural/odd after getting used to the Rotor oval chainring. The solution for this is to buy chainrings for the other bikes in the fleet.
  • The front shifting is compromised as it is indeed harder to shift and tune the derailleur for the front oval rings.
Well the onset of 1x11 drivetrains is here to the rescue for the front shifting issue as it is totally eliminated with a 1x setup. Rotor came up with a Narrow/Wide oval ring and we were excited to try it out. They sent us their Rex 1.1 setup with a PressFit 4130 bottom bracket. They also insisted we try a 172.5mm crank length, since they've found that to work well with their rings and with these new bikes with lower bottom brackets.

Rotor Crank with Massive Spindle

So we put it on and so far so good. There's no dropped chains and no shifting issues of course. We are seeing the benefits of the oval ring. With only one ring in front, the oval ring gives us a more ideal ring with good top end, but we seem to have an extra gear on those very steep wall climbs. The crank is incredibly stiff as well, and we like the more direct and efficient power transfer.

Rex 1 Crank Specifications

  • Arm Material: 7055 Alloy
  • Arm Length: 170 mm, 172 mm, 175 mm
  • Chainring Sizes: [not included]
  • Rings: 0
  • Spindle: 30mm, 24mm
  • Compatible Components: Rotor QX1/No-QX1
  • Claimed Weight: 489 g
  • MSRP: $500

QX1 Chainring Specifications

  • Material: aluminum
  • Number of Rings: 1
  • Teeth: 28 t, 30 t, 32 t, 34 t, 36 t
  • Compatible Components: SRAM XX1, [with adapter] Specialized , Rotor REX 1.1, 2.1
  • Claimed Weight: [28t] 50 g
  • MSRP: $125
Actual weight photos are shown below.

Rotor Crank Weight for 172mm

System weight with 172mm length cranks.

Rotor Ring Weight

30 tooth chainring weight.

Rotor BB Weight

BB weight with all the spacers.

For more information visit www.rotorbikeusa.com.