ROTOR UNO Details and Install

ROTOR installs its new 11speed hydraulic shifting group UNO on our Specialized Diverge.

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Rotor, the Spanish manufacturer best known for oval chain rings, has taken aim at the complete drivetrain with Rotor UNO, an 11speed group that shifts hydraulically. Yep, hydraulically. Working with both Magura and KMC, Rotor is making UNO at it’s facility in Madrid and after numerous season of spy shots and bike show back room demonstrations, Rotor UNO is available now. We invited Rotor over to the PELOTON Service Course to do a full Rotor UNO install on our Specialized Diverge test rig. Keep reading for all the details on the new group and check out the gallery above for detailed images of the install process.


While the hydraulic nature of the UNO group has resulted in some cries of needless complexity and potential failure that view is certainly not based on available evidence. We all rely on hydraulic systems daily and they are used in so many applications in part because of their simplicity and incredible reliability – car brakes and power steering, elevators, airplanes, construction equipment, etc . . . The examples are endless. There is no reason hydraulics done right shouldn’t result in incredibly reliable and consistent shifting. In fact, the major variable in hydraulic disc braking – the brake pads wearing down – is not present in the Rotor shifting system, meaning the shifting should stay dialed for essentially forever. Rotor says there is no real reason to bleed the system ever, in terms of ensuring accurate shifting, but it recommends a bleed every year as a simple systems check, as you should do with your car or any device your life may depend on.

It’s more than hydraulics that make Rotor UNO different. It shifts a 2×11 set up as do most other high end groups, but the indexing exists in the derailleur, not in the shift lever. Which, among other things, means if Rotor decided to make a 12, 13 or 14 cog cassette, you’d only need a new derailleur, your existing levers could potenially be compatible. Each derailleur has a single hose, and dual pistons, to allow the single hose to control both up shift and down shift. The old Acros hydraulic system relied on two hoses for each derailleur, one to up shift and one to down shift.

Rotor hoses have a 3mm exterior and 1mm interior diameter, similar to Di2’s 2.8mm cable, which means it routes in most Di2 ready bikes easily, with the occasional need for a file or Dremel to open cable ports that extra 0.2mm. Rotor UNO has no reservoir, just 8.5cc’s of fluid in the entire system, which helps keep shifting accurate, the feel as crisp as possible and reduces thermal expansion. UNO does have two inline barrel adjusters that offer enough adjustment to the fluid to handle even extreme temperature changes that could subtly alter shifting performance or feel.

With indexing being at the derailleurs, it’s the initial bleed that helps define the lever’s feel. Incidentally, Rotor also includes a complete bleed kit with every group. The levers shift essentially identically to SRAM double tap, small swing for a click down the cassette, large swing for a click up. That shift up the cassette, or the down shift to easier gears, can be adjusted to a 1-2-3 or 4 cog multi shift, depending on preference. The shift lever reach can also be adjusted. There is no question the feel at the lever is less direct than systems that index at the lever. The indication of a gear change is a bit ‘softer’ but we had no issues quickly adjusting to the feel and found the right gears on the first parking lot spin. The front lever does require a very long throw to shift from little ring to big ring, but we did ask a lot of the front derailleur, shifting a 46-30 front combo on our Diverge adventure rig. There are four front shift position – big ring, trim, small ring, trim – which, happily, meant we had no issues with cross chaining. Look for a full ride review soon in the pages of PELOTON Magazine.

Rotor is making its own cassette and it’s a beauty, with a high strength steel design to the first nine sprockets, with the final two pinned in place out of alloy. Currently only 11-28 is being made, but the group is compatible with other 11 speed cassettes from SRAM and Shimano, although you’ll be gaining some weight. At 135grams the ROTOR 11-28 is 40grams lighter than an 11-25 Dura-Ace cassette and 16grams lighter than a SRAM 11-25 XG-1190. The rear derailleur’s range is 11-21 to 11-30, although we’ve been experimenting with an 11-32 and we’ll report back soon. Instead of a b-adjustment screw the rear derailleur uses a pin set-up with five different positions, depending on your cassette’s max sprocket. The rear derailleur also has a small silver lever to release tension when changing wheels. ROTOR uses a KMC chain, but it’s got snazzy red accents that match the UNO group.

Overall, set up of this system seemed very similar to setting up a mechanical or electronic system – once you get over the novelty of your derailleurs sucking up blue hydraulic fluid. The most time consuming and annoying part of the process is internally routing the houses, as it is with any other system, and really dependent on the frame, not the components. The bleed was very simple, and with the indexing at the derailleurs, there is very little adjustment to get them shifting accurately. On the front just set the low limit and that’s it. Out back, the indexing handles it all, but there is a low limit set screw just to ensure your wheel won’t be damaged it something goes wrong.

Breaking is handled thanks to a partnership with Magura, using UNO branded MT8 disc brake calipers. It’s a proven brake, and we’re happy Rotor didn’t try to reinvent the wheel here. They work flawlessly. UNO also uses Magura RT8 hydraulic brakes for a rim brake UNO set up. We are not testing those, although hydraulic rim braking has always felt like an underwhelming half measure in our experience.

We’re currently in the process of our long term test of the Rotor UNO group and will report back on the shifting feel, ergonomics and performance in depth very soon in the pages of PELOTON Magazine.

Rotor UNO Weight: 1655grams – shifters, front and rear derailleur, filled, uncut hoses, post mount calipers, 160mm brake rotors, chain and cassette. (Editor – we chopped 52grams of hose weight building a 58cm Specialized diverge, so many builds will fall under the 1600gram mark for this kit. Adding cranks, rings and bottom bracket will take the complete group weight over 2200grams depending on rider choices. With the Aldhu crank, 52/36 rings and Rotor BB UNO weighs 2259grams.

There are two options to purchase UNO: the full group, which comes with Aldhu crank, or the derailleurs and levers only. Check this link from Rotor USA for a detailed break down of the different options: Rotor USA
$2700 for the full Rotor UNO group
$1750 for the upgrade kit, which has no drivetrain.
Full group weight, with cranks + 52/36 rings: 2259g
Upgrade weight: 1175g

11-28T UNO cassette included.
118-link UNO chain included.
Includes complete bleed/service kits for both shifting and braking.
Compatible with standard postmount frame/fork, and most standard flatmount frames with adaptors.
Same mineral oil used for both shifting and braking.
Compatible with all ROTOR cranksets, oval Q-Rings, and round rings


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