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Rotor's new ALDHU Carbon Arm Set is a very light, stiff option with a sleek look. The cranks form part of a modular chainset that will fit a very wide range of road or gravel bikes. The performance is excellent, which is just as well because they are quite expensive.
Rotor is perhaps best known for its oval chainrings, and more recently has been producing a range of aluminium components, including ALDHU cranks, which remain available. The ALDHU Carbon is the first full carbon road option it has produced, with the KAPIC Carbon mountain bike cranks released in 2019.
The ALDHU Carbon Arms Set forms part of a modular system, meaning that parts are purchased separately and combined to suit different bikes and riding styles. The cranks, axle, chainrings and spider if required are all available separately.
Endless options are possible – 1x or 2x, with all common chainring sizes available, plus a power meter option, the INspider, which I tested recently.
The modular system means the axle is separate and not attached to either crank, with both drive side and non-drive side having self-extracting bolts. Any play within the bottom bracket is then removed by using the preload ring on the non-drive side crank.
The cranks are available in 165mm, 170mm, 172.5mm and 175mm lengths, which cover the majority of preferences, although some rivals such as SRAM Red AXS and Shimano Dura-Ace 9100 do have more options. The aluminium ALDHU cranks are also available in a wider choice of lengths, starting at 150mm.
The carbon arms are a sleek, slim design with a gloss finish. For testing they were fitted to a setup that included a 30mm axle, INspider power meter and 50/34 compact chainrings. Setting them up is simple, and the tolerances give a very precise fit.
The performance and stiffness are impressive, with no flex that I could detect at all, including no chainring rub or deflection even under sprint efforts.
For the configuration on test, the total weight is 706g. The cranks themselves weigh a low 252g, although when comparing against other options the axle, spider and chainrings may need to be included.
With a 30mm axle (98g) fitted, the ALDHU Carbon Arms setup weighs 350g, compared to 334g for the Easton EC90 SL. The Easton set retails for £399, so very similar to the £394 for the Rotor when you include the £45 axle. Owning a set of the Easton cranks and able to directly compare, they are both excellent, but the Rotors just edge it, fitting together beautifully with close tolerances, and having a wider range of chainring and optional extras, making them a little more versatile overall.
When built into a full chainset, Rotor claims a weight of 528g with 50/34 chainrings, which stacks up well against 609g for Shimano Dura-Ace 9100, or SRAM Red AXS with 48/35 chainrings at 587g.
For the weight obsessed who also have deep pockets, there are a few even lighter options such as the THM Clavicula SE at 293g compact or 302g standard, costing €1,195. For 1x drivetrain offerings, there is the 3T Torino at a claimed 300g for arms, axle and spider, priced at £949.
Overall, the performance is impressive and the cranks look great. If you want a really light setup and are happy to pay for it, the ALDHU Carbon Arms are an excellent choice.
Impressive stiffness and low weight, with modular fit to suit all frame types
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road.cc test report
Make and model: Rotor ALDHU Carbon Arm Set
Size tested: 170mm
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Settings for everyone
Never has a crankset - like the ALDHU® Carbon crank- offered such wide configurations to meet the different preferences / needs of each individual cyclist.
Combine the cranks arms with different types of spiders, chainrings and axles. Looking for a power meter? Then choose the INspider, or you can also add it in the future; this is the main advantage of the the modularity of ROTOR cranksets.
In short, a solution that will adapt to your needs without having to replace the complete set.
Tell us some more about the technical aspects of the product?
Weight: 260 g (172.5 mm - only crank arms)
Sizes: 165 mm / 170 mm / 172.5 mm / 175 mm
Q-Factor: 147 mm (standard axle) / 152 mm (offset axle)
Chainline: (2X) 43.5 mm (standard axle) / 46 mm (offset axle)
Chainline: (1X) 44.5 mm (standard axle) / 47 mm (offset axle)
Compatibility: BSA30, ITA30, BB30 bearing kit, PRESS FIT 4630, UBB4630, BB386, PRESS FIT 4130
Tell us how the product performed overall when used for its designed purpose
They're light and feel very stiff. The modular format means virtually all bikes and bottom bracket styles will be covered, and it was easy to put together.
Tell us what you particularly liked about the product
Love the look, and the tolerance of the fit makes them easy to install.
Tell us what you particularly disliked about the product
Nothing in terms of function, but having to buy parts separately racks up the price.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
It is similar to the Easton EC90 SL when you factor in the price of the axle, but more than the Praxis Works Zayante Carbon. You can spend a lot more though...
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
They might cost a lot, but if you want lightweight cranks that are also very stiff and can be fitted to various bike and bottom bracket types, the ALDHU Carbon Arms are an excellent choice.
About the tester
I usually ride: My best bike is: Cannondale SystemSix
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: road racing, cyclo cross, sportives, mtb, Lots of gravel style riding
Matt is an endurance nut who loves big rides and big events. He's a former full-time racer and 24hr event specialist, but now is also happy riding off-road on gravel bikes or XC mountain bikes and exploring the mountains and hills of Mid Wales.