First Ride: Rotor Uno hydraulic drivetrain

Rotor’s Uno hydraulic drivetrain offers fast and precise shifting and is a viable alternative to electronic and mechanical systems.

With Rotor diving in the drivetrain game this year, five brands will soon be fighting for position within the pro peloton this season. SRAM, Shimano, and Campy are of course the usual suspects, and each company now offers both mechanical and electronic drivetrain options; FSA is still scheduled to hit the race scene sometime in 2016 with its new electronic shifting; and Rotor rounds out the group with its Uno hydraulic drivetrain system.

We’ve known about Rotor’s hydro shifting for some time now and VeloNews editor in chief John Bradley even got his hands on it at Eurobike last October. But now, thanks to a Rotor product launch in Madrid, Spain, we’ve hopped aboard Uno, putting it through its paces on wet and snowy mountain roads, to see how this new approach stands up to its electronic competition.

The short answer? Rotor’s Uno hydraulic drivetrain and brakes offer fast and precise shifting, powerful braking, and this group is a viable alternative to the electronic and mechanical systems currently claiming the market space.

Benefits of hydraulic shifting

Friction causes mechanical shift cables to perform poorly when routed through tight twists and turns with tricky internal routing pathways. Hydraulic lines are not affected in the same way so all the new aero-integrated bars and sharp frame shapes won’t cut down on shifting crispness.

Hydraulic shifting is also lighter than both electronic and mechanical systems. Because of the low volume and low pressure needed for shifting movenents, Uno uses 3mm diameter hydraulic lines (compared to 5mm brake lines). Less material means less weight and Uno is a claimed 417 grams lighter than Shimano Di2 disc and 99 grams lighter than SRAM eTap. These hydro lines are so small that they fit through Di2 internal routing holes in bikes currently on the market. Naturally, no heavy batteries are required either.

Uno’s small, hydraulic shift lines use a 30-percent Glycol fluid instead of mineral oil because it is more stable at extreme temperatures. Rotor claims the Glycol fluid will work down to -15 degrees Celsius (5 degrees Fahrenheit) and up to 80 degrees Celsius (176 degrees Fahrenheit).

Uno’s hydraulic shifting is a closed system, unlike most hydro disc brakes, which have an open system with a piston and reservoir. This means (theoretically) that no dirt, no water, no anything should make its way into the shifting lines, and you won’t have to bleed or replace the hydraulic fluid. Only long-term testing will prove this right or wrong, but it makes sense in theory.

Sounds like a win-win for Rotor’s Uno hydraulic group right? For the most part, it’s true. This is a well-designed, well-tested new group. It feels like a mechanical drivetrain but performs close to electronic shifting.

First ride impressions

Uno feels much like SRAM double tap shifting, both in the lever throw pattern and the shifting actuation. Like SRAM, to shift the rear derailleur, push the right lever in until it clicks once to a harder gear (smaller cog). This shift direction is limited to just one gear change with each paddle throw.

To shift to an easier gear (bigger cog), press the lever past the first click until it clicks again. For this, there is a multi-shift setting: a screw on the rear derailleur has four marked positions that limit it to one, two, three, or four gear changes depending on how far in or out the screw is turned. This is a nice feature so that you can dump several gears at once if the terrain suddenly goes up, and the multi-shifting is fast as it jumps over multiple cogs without hesitation.

The front derailleur acts similarly to the rear but without multi-shift functionality for obvious reasons. Using the left-hand shift paddle, press in until the first click to shift down to the small chainring or continue pressing in past that first click to shift up into the big chainring. Both big and small rings have a trim function built into the shifting and this makes for almost no chain rub across the entire cassette.

Precise and quick shifting

Unlike some mechanical shift systems, half-shifts are not an option with the Uno group: It’s all or nothing. This is because the shift indexing mechanism, called HyStep, is actually located in the derailleurs themselves, not in the shifter bodies. So when you shift up or down, the derailleur moves a prescribed amount to make a clean, precise shift to the desired cog. Mechanical systems pull on cables to make this happen and if you don’t push the lever all of the way, the chain can get caught between shifts and will bounce around between cogs until it settles on one or the other, or until you shift again with a full swing.

Uno was also impressive with its shifting speed, especially for the rear derailleur. Pushing the right-hand lever sent the derailleur immediately into action in either direction. There was no noticeable lag time like we’ve seen in some electronic systems, which can be frustrating when sprinting or when you need that instantaneous kick into another gear.

The front derailleur, on the other hand, was a bit less responsive, and I initially struggled to drop the chain from the big chainring to the little one when we started climbing. Part of this could have been from the Rotor Q-rings on my test bike with the oval shape holding onto the chain for too long when under tension from hard pedaling. Once I backed my effort off just a touch, the chain easily dropped to the little ring.

By the end of the ride of about 50 miles, I was shifting the front derailleur with no problems. Whether the shifting system just need to break-in, since this was the first ride on this bike, or I adapted to the system and started shifting differently, I’m not sure. But I’m eager to dig into this question in a long-term Uno group test.


Because Uno’s indexing mechanism is located in each derailleur, the shifter body innards are fairly sparse, leaving Rotor plenty of freedom when designing the size and shape of the new shifter bodies. And the engineers settled on good-looking hoods that are medium height and width, similar to Shimano and SRAM. Most of the journalists at the launch agreed these hoods are comfortable and appropriately sized, but they felt a touch too wide for my taste. I have smaller hands, which could explain that impression.

What my little hands did like was the shift lever reach-adjust function that allows you to move them in toward the shifter body so little fingers like mine can actually get a secure grip on the levers.


Each piece of the Uno group will be produced in Madrid and then sent to Germany where Magura will prepare the hydraulic systems and fluids. Then, the group will be shipped fully assembled to distributers, dealers, and customers. This means, to route the hydraulic shift lines internally, you’ll need to cut the line, route it through the bike, and then reattach it to the derailleurs. But before you start sweating about cutting hydro lines, remember that this is a closed system (think about covering one hole of a straw with your finger and then lifting it out of your soda — nothing comes out of the bottom of the straw, right?). The hydro fluid should remain in the line and make for easy reattachment to the derailleurs.

Adjusting both front and rear derailleurs during initial setup also sounds straightforward and requires only one bolt for alignment. Set up the rear derailleur by aligning it with the smallest cog (using the bolt) and from there, the pre-set shifting steps take the derailleur up and down the cassette for near-perfect shifting across all cogs.


Uno’s group comes with the option of rim brakes or disc brakes: both are hydraulic, both were designed by Magura, and both use Magura’s Royal Blood hydraulic fluid (an environmentally friendly mineral oil).

The rim brake system is a closed system (like the hydro shifting) and theoretically should be maintenance-free with no need for bleeding. On the other hand, the disc brake system (available in either post-mount or flat-mount models) is an open one because disc brakes create a large amount of heat, and the hydraulic fluid needs space to expand when it gets hot. So the disc brake system includes reservoirs for fluid expansion and will need to be bled like any other disc brakes. Fortunately, there is an easy to access bleeding port found on the shifter bodies.

Nuts and Bolts

Rotor claims the weight of the disc brake Uno hydraulic system is 1,604 grams. That’s approximately 417 grams lighter than Shimano Di2 disc, 10 grams lighter than SRAM Red 22 disc. (Note: Weights for all three groups are without cranksets.)

The suggested retail price for Uno’s disc or rim brake options is set at 2,499 euros or about $2,499. (For comparison, a Dura-Ace Di2 hydro disc group can be had for about $2,600 on Competitive Cyclist’s website, and SRAM’s Red hydro group is similarly priced.) The full group includes front and rear derailleurs, disc or rim brakes, shifters, hydraulic lines and fluids, a Rotor machined 11-28 cassette, and KMC X11SL chain. A cranks is not included in the group because Rotor says it makes too many crank and chainring options and would rather cyclists choose the right one for themselves rather than be forced into something because it comes with the set.

Each piece of the Uno group (besides the KMC chain) is produced in Madrid, Spain. Rotor keeps all quality control testing in-house and can make minor changes to the group more quickly than working with overseas manufacturers.

While the group will come with Rotor’s newly developed three-piece cassette, Uno is SRAM and Shimano compatible so you won’t have to ditch your current cassettes, chainrings, or wheels.

Satellite shifting options like time-trial shifters or sprint and climbing shifters are in the works but they won’t immediately be available with the Uno group. Rotor did say that adding these additional shifters should be a straightforward matter of splicing an additional hydraulic line into the system.

Uno will hit the market this July where it will be available as an aftermarket product. But Rotor says it is in the process of securing OEM contracts for several 2017 bikes models.

Rotor provided travel and accommodations for this product launch.