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…


    • Hexsense on

      It’s the draw back of this design.
      Quarq Dub D1 bond in spindle with left arm vs this, which require hardware for attach/detach left arm from the spindle.

      The splined spider interface also weight more than 8 bolts interface Sram use. But it has advantage that it allow very fine tune of Oval ring rotation.

      Basically, if you never want to customize spindle length, and don’t use oval chain rings. You just pay the weight penalty without using its benefit.

  1. Cheese on

    “from their manufacturing headquarters in Spain”
    Are you saying that they aren’t sourcing their carbon cranks from Asia anymore?

  2. barael on

    “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)”

    Seems like the price for a pair cranks, not a full crankset seeing as the current AL cranksets costs more than that (and pair of AL cranks somewhat less).

  3. DRC on

    I had heard grumblings on the forums about this crank. I’ve been itching to pull the trigger on an EC90SL crankset with a power2max, but wanted to see what Rotor had coming since I’ve been very happy with the 3D+ and 3D cranks on my last two bikes.

    But that price… $120 more than the Easton for basically the same weight? And $100 more than their (probably very similar) Kapic Carbon mtn crankset?

  4. Oliver on

    Not compatible with BB86 for some unknown reason. Also, €650 for their spider power meter is just a joke, at this point. Same kind of Sigeyi powermeter is 40% of the price (not 40% less), just as accurate, great build quality, and lighter.

    • John on

      @Oliver: BB86 is Shimano’s press fit bottom bracket standard for 24mm steel spindles. While a 30mm spindle will technically fit a BB86 bottom bracket, the tight fit requires IMO tiny bearings which can have questionable durability. YMMV.

    • David on

      The original aldhu and vegast were also not bb86 compatible on release, but both now have 24mm spindle versions and I would expect this is coming from rotor as well.

      Sigeyi have problems (look out for gplamas comments on them. The rotor inspider has problems as well, but supposedly still better than the sigeyi.

  5. John on

    I *just* got a power2max w/ alloy Rotor ALDHU cranks for 24mm spindles and p2m 46/30t chainrings for the gravelbike, and was happy as a pig in s*%# until I see there are now carbon ALDHU cranks. LOL! It’s probably best for my sanity that these aren’t available in 24mm cranks yet.

        • Treve Kneebone on

          I don’t think so. I have the 24mm specific Vegast crank arms that use the same axle as Aldhu. Assumed that the axle/crank interface is smaller in diameter?

        • Hexsense on

          Rotor didn’t design their original interface with 24mm axle in mind. If you think about it, one side of the axle interface must be smaller than the bearing, so that it fit through the bottom bracket bearings before we attach the crank arm.
          The right side has spline for chainring mount so the left side must be the small interface side. The problem is, the original Aldhu 30mm version crankset has the crank arm interface too big to fit through 24mm bearing…
          On their 24mm version, the left crank arm interface have to be changed and is not compatible with 30mm version.

          • Hexsense on

            ^ If only Rotor made the 30mm version left crank arm interface small enough to fit through 24mm bearing from the beginning, they wouldn’t have to separate 30mm/24mm crankarms incompatibility as it currently is.


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