rotor uno hydraulic shifting group technical details overview

Last fall, Rotor UNO was unveiled as the first complete hydraulic drivetrain group, offering everything from shifters to derailleurs, cranks to cassette, and even brakes. And it offered a unique, single line system that was able to handle up and down shifts by moving fluid in a single direction.

The differences go beyond liquid connections between components – all of the moving mechanical shift parts are at the derailleurs, not the shifters. That, coupled with lossless hydraulic lines, means crisp, instantaneous action with a familiar mechanical feel.

Now, finally, the group is near production and we have all the tech details, weights and first rides. We also learned how the group came to be, what’s changed, and why Rotor thinks you’ll like it…

rotor uno hydraulic shifting group technical details overview

UNO is an evolution. Rotor started with chainrings, which turned into cranks, which turned into power meters. This is the next step. While they may not have known it at the time, all those years of developing oval chainrings that would shift with other peoples’ derailleurs and chains meant they learned a whole lot about how to make things shift.

They started athlete testing on UNO in November 2015, and in the few months since, they learned, and made more changes to the system in those months than in the entire year prior.

If you could take all the positives of both electronic and mechanical groups, Rotor believes you’ll find them in UNO. It’s lightweight – lighter than any of the other groups with hydraulic disc brakes. And you get most of the firm, direct feel of a mechanical system. And it’s modular like electronic, meaning you’ll be able to add or change shifter types with minimal fuss by simply splicing the hydraulic line. Yes, that is a nod to future development (think TT, triathlon or even mountain bike).


They call that combo HySTEP, and the first part stands for Hydraulic Smart routing, referring to the thin, flexible lines that’ll easily fit into aero frames and small tubes.

Hydraulic’s key benefits include smooth activation of every shift with no friction. And because they don’t need to worry about heat expansion, it’s a closed system that will remain in perfect sync forever with virtually no maintenance. No batteries to charge, no cables to clean or replace. It’s also future compatible with additional hydraulic systems.


This video shows:

  • Closeup of the ratcheting mechanism’s dual stops. As the top one pushes it one way, the bottom one catches and holds it. To shift the other direction, the bottom one pushes and the top one catches. Which one does what depends entirely on how far you push the shifter.
  • The front derailleur uses a three step clocking. Two small ones for trim settings on each chainring, and one big one to shift between gears.
  • The rear derailleur has 11 steps. As the clock gears turn, they move the rack you can see on the outside bottom. That rack is linked to the parallelogram that actually moves the derailleur.
  • UNO can downshift (easier) up to four gears at a time, and a single upshift (harder) at a time. On the stand and on the bike, it moved quickly and quietly, at least as good as any other top level group I’ve ridden.

The shifting system uses a 30% glycol solution, which is stable from -15º to 88º C (5º to 190ºF), rather than mineral oil or DOT fluid. It runs through 3mm flexible shift hose that makes internal routing easy, even with tight bends.


rotor uno hydraulic shifting group rear derailleur

All of the clocking and mechanical gears are housed in the two tubes and that round part at the back end of the rear derailleur.

rotor uno hydraulic shifting group rear derailleur

The clocking mechanism’s design and location on the derailleur rather than the shifter body is that it has absolute precision. The steps on the ratchet are aligned perfectly with the cog spacing, so once it’s set, it’ll repeat perfect shifts every time with no degradation from cable stretch, temperature, etc. You can adjust the alignment during initial set up with a single screw plus an upper limit screw…

rotor uno hydraulic shifting group rear derailleur

…and then you can set the number of downshifts that the lever is able to push from 1 to 4. However many lines you see on that barrel (green arrow) is how many shifts per push you can get out of it. It’s not all or nothing…you can still shift just one gear at a time, or two, or three, up to four. They put this adjustment in because some of their sprinters wanted to be able to hit the lever hard during the final sprint and know exactly what it would do, one shift at a time. For others who want to be able to dump a lot of gears at once, you can set it to your preference.

rotor uno hydraulic shifting group rear derailleur

Return to Origin is among the most fascinating features. In the unlikely event you damage the hydraulic lines, you can flip that gray lever forward to release the clocking mechanism and the derailleur will drop down to the smallest cog. Close the lever and you can then physically push it up to the cog you want. So, you could push it into an easy gear for climbing, then put it into a harder one for descents. The more practical application of this is making wheel changes quicker and easier, and protecting the derailleur from damage during transportation.

rotor uno hydraulic shifting group rear derailleur

One thing worth mentioning is that the entire group, save for things like the return spring and hoses, is designed, manufacturers and assembled at Rotor’s factory in Madrid. The metal parts are all machined or forged there, so they share the same aesthetic as their cranks and chainrings, giving the complete group a unified, top tier appearance.

From the bottom you can see the upper limit screw, rack and gear alignment adjustment screw and the hose banjo. The bleed port is on the side, which you should only need to use once for initial installation. The group includes a roll of hose and bottle of fluid.


rotor uno hydraulic shifting group front derailleur

The front derailleur has a single bolt set up for quick, easy adjustment. There are no limit bolts on the front because the clocking mechanism creates fixed shifting positions – once its position is set, there’s no need to set limits.

rotor uno hydraulic shifting group front derailleur

rotor uno hydraulic shifting group front derailleur

The clock gears move a rack here, too, which is connected to the inside of the parallelograms and pushes the arms out to the big ring. A return spring lets it fall back onto the small ring.


rotor uno hydraulic shifting group shifters

One of the biggest changes between pre-production and final versions are that two separate shifter lever bodies will be offered, one for rim brakes and one for discs. With disc brakes, it’s an open system to accommodate heat build up and uses a traditional master cylinder reservoir to handle expansion. For rim brakes, heat build up is negligible, so it uses a closed system, which means virtually no maintenance throughout its life.

rotor uno hydraulic shifting group internal features

rotor uno hydraulic shifting group internal features

rotor uno hydraulic shifting group shifters

The actual internals are very small, but their research showed that riders preferred a slightly larger hood. However, they will offer smaller hoods in the future. The hump at the front is intentionally large, too, which provides a more secure feel.

rotor uno hydraulic shifting group shifters

rotor uno hydraulic shifting group shifters

The brake lever is carbon and has a tooled reach adjust is accessible from under the top of the hood. The shift lever is alloy and is attached to the brake lever, so it has no additional reach or position adjustments. As the shift lever pivots, it pushes a piston (silver bit in pic above) to move fluid toward the derailleurs.

A short push releases the derailleur for an upshift, and a longer push makes 1, 2, 3 or 4 downshifts (easier) depending on how you have your RD set. The dual ratchet system inside the rear derailleur means it’ll catch and hold itself if you push halfway into a shift but don’t complete it.


rotor uno hydraulic shifting and magura disc brakes

The brakes, both rim and disc, use reinforced 5mm Magura housing with that brand’s Royal Blood mineral oil. That’s not only more environmentally friendly than DOT fluids, it’s also non-hydrostatic, meaning it won’t attract and absorb moisture over time.

rotor uno hydraulic shifting and magura disc brakes

Rotor partnered with Magura because they were already experts in hydraulic systems with more than 100 years making brakes and more for both bicycles and motorcycles. They already had service centers in place globally and had all necessary safety testing in place.

rotor uno hydraulic shifting and magura disc brakes

Here, they’re using MT8 NXT calipers. Rotor said they’re the lightest and safest system for road disc brakes. The caliper body is slightly larger than some competing units, which helps dissipate heat better. They always spec 160mm steel rotors, so there’s no rider weight limits. It’ll be available in both ISO and…

rotor uno hydraulic shifting and magura disc brakes

…all-new flat mount designs.

The bike shown here used Magura’s Storm SL rotors, but production groups will ship with the standard Storm rotors, which have fewer and smaller round holes on the braking surface rather than the slotted design shown here.

rotor uno hydraulic shifting and magura rim brakes

The Rim brakes are modified versions of the Magura RT6/8 rim calipers, which are a very slim, aero design that doesn’t protrude to the side of the frame or fork like a mechanical caliper can. The rim brake lever and calipers are designed to give them a massive 14mm throw (at the pad, 7mm per side). Combined with the two new adjustments shown below, it allows them to fit a wide range of rim widths.

rotor uno hydraulic shifting and magura rim brakes

Since it’s a closed system, Rotor added two adjustment methods. On the caliper itself, there’s a new adjustment knob that functions as a quick release – push it down and twist to open up the caliper 6.5mm.

rotor uno hydraulic shifting and magura rim brakes

Then, an inline barrel adjuster adds 8.5mm of adjustment, which is important in a race environment where a team might be riding a wider rim but need to use a narrower wheel from neutral support and not have to worry about adjusting too many things. Once on the bike, the rider can easily reach the barrel and adjust pad contact en route.


rotor uno hydraulic shifting group cassette
Just pretend for now…Rotor’s cassettes weren’t ready for our test rides, so our bikes had Shimano Ultegra units.

Like the other parts, Rotor is machining the cassette in house, too. It’s a three-piece unit that’s bolted together, and each part is interchangeable. The lower two segments are steel, and upper is alloy and contains just the two largest cogs.

It’ll only be offered in an 11-28 to start, but will have additional sizes in the future. Claimed weight is under 150g. The cassette is designed for a SRAM/Shimano freehub body. Those with a Campy freehub body will need to run a Campagnolo cassette for now. Which is fine, because they say their cassette will work with other 11-speed drivetrains, and other brand cassettes will work fine with their system.

Not shown, the complete group will ship with a KMC X11-SL DLC chain that uses their quick link connection, hollow pins and X-Bridge plate design. It’ll have a custom DLC coating that’s all black with red pins.


rotor uno hydraulic shifting group actual weights

Dry parts on our scale measured out at:

  • Right shifter – 168g
  • Left shifter – 167g
  • Front derailleur – 118g
  • Rear derailleur – 211g

The hoses will weigh virtually nothing, and the cassette was not available to weigh. Here’s how Rotor shows their system stacking up against currently available product:

Rotor UNO weight comparison chart

NOTE: SRAM hydro brakes show lever-and-brake combined weight as “Extras” since they’re sold as a set.



Groups will be available in July in limited quantities with standard rim or disc brakes. Pricing is €2,499 for the complete group with disc or rim brakes, sans crankset. Ships with bleed kit, Royal Blood and glycol solution.

Since Rotor makes so many different cranks and chainrings, the complete group will not include them. This lets you add on which ever one you like. They showed it with the new 2INpower cranks, which combine separate left-and-right leg power measurement. And they might be a good choice, Rotor says last year they sold ~12,000 power meters with only seven returned for product defects. That’s impressive, but it’s a key a reason they make and assemble so much in house…total control. We’ll dive deeper into 2INpower’s tech features on a separate post.


Everything is designed, manufactured and assembled in Madrid. For production models, the brakes will be factory filled, bled and sealed at Magura. Meaning, the shifter lever assembly will be built at Rotor, then shipped to Magura to have the brake hoses and calipers installed, bled and checked, then the entire unit will return to Rotor for final assembly, quality check and packaging.

Look for it to get OEM spec on Cervelo initially, largely thanks to their strong pro team ties for Bigla and Dimension Data.

Full ride review coming soon…


  1. Those rim brakes seem awfully close. What is the advertised tire clearance? Also, that cassette is clearly a Shimano Ultegra unit – not their own.

  2. I love Rotor gear but I couldn’t imagine throwing those barrel adjusters on the front end of a modern aero bike.

  3. I actually really like this idea, but at 2500 Euro it’s dead in the water. It is just way to expensive vs the street price of Red or Di2. Sure they compete on MSRP, but who ever pays that?

  4. Seems like a lot of potential pain in the ass type problems to occur.

    A lot of this new stuff seems to be created just to be created and not a lot of benefit to it.

  5. I question their lack of front derailleur limit screws. Today’s chainrings have varying lateral spacing with respect to each other. Older systems had the chainrings relatively close to each other. 7900-current Shimano has the outer ring spaced further out, with the space in between filled with their composite pickup ramps. If this system allows for Shimano cranks, it’ll throw the chain off the big ring on Rotor’s own systems, round or oval.
    Something is missing. There must be a high limit screw.

  6. I’m looking forward to this groupset and reviews on it mainly as I like keeping my bikes main functionality mechanical. Hydro is leaps better than cables.
    Hopefully price is competitive…it’ll be interesting to see how it is priced compared to mech and electric competition.

  7. i touched these and shifted them… it was great… i want this group… especially this could make a great MTB group… not been a fan of electronic… but this is interesting to me…

  8. The major flaw I see with this design is shown in the picture Rotor-UNO-hydraulic-shifting-group-der-rear08.jpg of the rear derailleur. That exposed straight gear/ratchet mechanism looks like it would work great when its dry and clean out, but if you had any mud, ice build up there, then you loose all gears, which makes this incompatible (as it sits now) for cross, mountain, or just crappy weather (see giro mnt stages where guys had a half of inch of ice built up on their helmets)

  9. Seems like a lot of stuff to get dirty and gum up on the derailleurs. I would like to see how it does on a cross/gravel bike caked in mud.

  10. Great mechanism, but I am just curious that this RD ratchet system is a copy of SRAM’s double tap shifter?? Or they simply paid for patent settlement?

    • I think the difference is in the implementation. SRAM retains indexing in its shifters. Rotor doesn’t, and pushes them downstream to the derailleurs.

      They may act the same way but the mechanisms are totally different. That might be a large enough difference for patent non-infringement.

  11. Hydraulic shifting? I really hate bleeding my brakes but if the brake is not adjusted 100% correct, the worst case is that the disc scrathes a little bit, or the brake point is not so well. If the derailleur is not bleeded right gearchange will not work properly?
    That does not sound like an option to me.

  12. Will there be a comprehensive spares availability? Putting the indexing in the derailleur will lead to greater precision, irrespective of cable or hydraulic, but puts the expensive parts in the bit that gets most often busted in a crash.

  13. Fantastic. I’m in. I’ve been waiting for a full hydraulic system for 5+ years. Now I know why it took so long. Somebody had to really break the existing mold. Campy, Shimano, SRAM? Nope, ROTOR. I’ve waited and waited to how this would develop. I mean how long did we wait for hydraulic road brakes? I really dislike the idea of electronics and motors on a bicycle. Seems unnecessarily complex. On a 1x mountain bike this would be amazing.

    Tyler, your reporting and detailed descriptions of this product was really good.

    BTW, this is the most positive, least snarky comment ever made by the illustrious Hotep!

  14. looks like a great system and no batteries! I always find it funny that people commenting on new products assume to know more about the potential problems than the engineers that spend thousands of hours and millions of dollars developing the equipment. Everything has its good and bad points, it’s a matter of personal preference usually and an the acceptance of quirks in whatever system you choose for yourself.

    • Engineers seldom ride the bikes they develop. Riders do ride them. Therefore, it is the latter who knows about the problems first hand. Imaginative riders know about the problems beforehand.

      This is not to take any proficiency away from the finest engineers; they just do not ride their products enough. Riders (we) do. Consequently, if their product has little value in our eyes it will not sell well, or at all.

      Designers aint’t buying designer clothes (or bikes, for that matter). The public does. Riders do. Consider it thoroughly: we are well informed, experienced bunch. Cobbling together some Magura with some Justmadeforthebikeshow is not going to sell if there is little sincere value behind their product. Design alone is no value, just looks. Wanna pay for the looks? Boy, go for it full hog! I’d rather pay attention to the value of it, if it has any.

      • I understand that the engineers that design these things may not ride but the companies do employ test riders in their development teams. I have considered it and after 35 yrs or so riding bicycles I can still see merit in the design as it looks like it works and if you care to look at some reviews on youtube it seems others also consider that it has merit. Not all new design concepts, not that it’s new, are rubbishy gimmicks that look pretty at shows, some of them offer an alternative to current design principles for those that wish to explore them!

  15. I remember when Mavic first put out their electronic shifting back in the day and thought it was a crazy idea/wondered who would buy it. A few years down the road with a bit of refinement everyone seems to be tripping over themselves to ride it.

    This might be the same sort of situation, so I am curious to see how it performs.

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