Rotor Aldhu Carbon crankset adds ultralight option to modular drivetrain system

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Rotor’s known more for their oval chainrings, but we’d argue their complete cranksets are very much worth a look, too. They’re sleek, light and stiff…and now there’s an even lighter option: The all-new Rotor Aldhu Carbon comes in at just 260g for the arms, and the rest of the kit doesn’t add much more…

Rotor Aldhu Carbon crankset details

new rotor aldhu carbon fiber crank arms

First up, it’s worth a quick recap of how Rotor’s cranksets work. It’s all modular. You choose the arms, the spindle, and the chainring. And whether you want a power meter-equipped spider, spindle, crankarm, or none of that. You can even choose between round and oval chainrings. Then piece it all together to create the exact system you want.

new rotor aldhu carbon fiber crank arms shown on a bike

The new Aldhu Carbon builds on the already very light alloy Aldhu cranks introduced in 2018, giving us an even lighter carbon fiber crank arm option. Here’s the official specs:

  • Weight: 260g (172.5mm w/o chainrings & axle)
  • Sizes (mm): 165 / 170 / 172.5 / 175
  • Modular system: OCP Mount or Spider 110×4
  • Axle: 30mm
  • Axle weight: 96g
  • Q-Factor: 147mm (Road standard axle)
  • 152.5mm (Road offset axle)
  • Chainline: 45mm (1x chainrings) / 42.5mm (2x chainrings)
  • Technologies: OCP Mount / Carbon

What does a complete Aldhu Carbon crankset weigh?

rotor aldhu carbon fiber crank arm compatibility chart

It depends on how you piece it together. there are a couple ways to do it, with and without power meters.  The most basic setup is crank arms (260g), spindle (96g), spider (48.5g, 110BCD, 4-bolt), and 186g for an oval direct-mount one-piece 52/39 chainring combo. Total weight: 590.5g.

new rotor aldhu carbon fiber crank arms with power meter spider and single chainring

A 40-tooth 1x direct-mount chainring would drop 94g. A power meter spider would add 100.5g.
new rotor aldhu carbon fiber crank arms with one-piece double chainring
Rotor claims the complete weight for a set with 50/34 compact chainrings is just 523.5g, which is about 100g lighter than the same setup with their alloy Aldhu arms. And, these carbon arms are a claimed 11% stiffer vertically and 36.1% stiffer horizontally.

Their InPower power meter spindle is only available as a permanently attached unit to the non-drive alloy crank arm, so for now it’s not available as an option with the carbon arms. There’s also quasi-aero and full aero chainrings, standard 110BCD chainrings, etc…the chart above shows just how many ways there are to put these together.

new rotor aldhu carbon fiber crank arms shown on a bike

Like all of their cranksets, the spindle’s interface has a separate splined mounting shelf for the chainrings. This lets them offer five distinct rotational positions for their oval chainrings, a system they call O.C.P., to fine tune where the peak leverage is based on your particular anatomy and riding position.

new rotor aldhu carbon fiber crank arms shown on a bike with rotor 1 by 13 drivetrain group new rotor aldhu carbon fiber crank arms shown on a bike

The Aldhu Carbon cranksets will come in 165/170/172.5/175mm lengths. They start shipping in February 2021 at a retail price of €389 ($473 / £346) with free shipping from their manufacturing headquarters in Spain. Prefer mountain biking? They released their first-ever carbon fiber crank arms in 2019, called the KAPIC, for MTB.

We’ve got a set in for long term review, look for first impressions and actual weights very soon…

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