Rotor Uno MTB-Shifting System Review

The Spanish component specialist Rotor is world-renowned for its exquisite CNC-machined cranks and oval chainrings. After the Madrid-based company ventured into road racing with the hydraulic “Uno,” they are now making a big push into the mountain biking sector. We exclusively tested the wireless Rotor Uno MTB to see if it can pose a threat to the dominant players SRAM and Shimano.

Installing the Rotor Uno is generally straightforward, but it significantly differs from the competition. While you start with basic mechanical adjustments with SRAM or Shimano, Rotor won’t work at all without the app.

A true unique selling point is its versatility: The Uno can handle everything from an old-school 3-speed cassette to a future 14-speed solution. Particularly exciting: Each individual gear can be adjusted and fine-tuned via the app. So if you’re using an aftermarket cassette that doesn’t shift smoothly, you can make surgical adjustments here.

Critique: For “old-school mechanics,” the complete app dependency might be off-putting. Additionally, the lower limit screw is hidden under a plastic cover – an unnecessarily fiddly affair.

Visually, the Uno makes quite an impression at first, but weaknesses reveal themselves in detail. Rotor relies on small 2 mm Allen screws for adjustments. These are hard to find on most multitools and are prone to stripping extremely quickly in mud and dirt.

The durability of the surface treatment was also disappointing in the test: after just a few weeks, the black coating at the contact points started to peel off. Additionally, the cables on the derailleur are relatively exposed, and the design has many small angles where dirt stubbornly accumulates.

Tester’s tip: If you ride a lot in the mud, be sure to clean the derailleur meticulously on a regular basis, as the charging contact needs to be 100% clean for the power to flow. A metallic chip that stuck magnetically to the charging cable caused quite a bit of frustration during charging.

In practice, the Uno shows two faces. The shifting speed is impressive and more on par with the fast Shimano systems than with the somewhat more leisurely SRAM competition. However, the chain clatters quite loudly onto the cogs, and while shifting under load is possible, it is by no means as “smooth” as with a T-Type group.

Moreover, the shifter tends to move backward during the ride despite being tightly mounted, as the locking mechanism doesn’t engage 100% securely. Again, the Torx 15 screw used for locking is simply too small. You can adjust this with washers between the clamp and the lever arm, but you don’t want to do that with a premium product.

The biggest “no-go” for many riders might be the fixed battery. With 600 mAh, it offers double the capacity of a SRAM battery, but once it’s empty, the bike stops. A quick swap on the trail or a parking lot check (“Did I bring the spare battery?”) is not an option. Here, Rotor made an impractical decision in favor of design. The overall battery life of over 30 hours is decent, but the option for a replaceable battery is still necessary.

You can get the derailleur, also known as the rear mech, for €690 on the Rotor homepage. That’s about €100 more than a current Shimano Di2. Currently, there are several offers in this price range where you can get an entire SRAM GX Eagle Transmission group including cassette and chain.

With this in mind, Rotor needs to improve its pricing. The market will certainly reveal significantly lower prices here. In terms of weight, the derailleur is on par with 402, or even slightly lighter than the top groups like the SRAM XX Transmission and Shimano XT. The weight savings are in the range of 20-30 grams and are not truly significant when considering the whole bike. You’re definitely getting a lightweight derailleur.

We have also extensively tested the Sram AXS Transmission and the mechanical Sram Transmission. And if you’re interested in e-bikes and drivetrains, you might find our test of the Pinion MGU interesting.