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Rotor Uno: First ride review

8 Mar 2017

Cyclist tests the first production sample of the Rotor UNO groupset, which uses hydraulic fluid to change gear.

Buy the Rotor Uno from Tredz here

Rotor's hydraulic UNO groupset has been the focus of speculation for some time. The chainring and component manufacturer has been eager to expand on its current drivetrain components, Q-rings and cranksets. The Uno groupset has been in development for more than six years, and has spent the last six months in testing amongst pro riders such as Team Dimension Data, but as yet no mere mortals have tried the system.

At the grand unveiling of the new groupset at Rotor's global HQ, Cyclist seized the chance.

On first hearing Rotor was releasing a groupset based on hydraulic actuation, many speculated that with patents being too tight to enter the mechanical or electronic groupset market, hydraulics was the only option remaining. Rotor is quick to dismiss such speculation, though, highlighting the numerous functional and maintenance advantages of hydraulics for shifting.

Rotor Uno disassembled shifter

'We are talking about a closed hydraulic system that will suffer no friction throughout its lifespan,' explains Lars Janssen, Product Manager at Rotor. 'The shifting will remain consistent as there is no cable stretch, and there's no need to replace oil. This is a very low maintenance.' 

Low maintenance then is certainly one appealing factor, as is the consistency of pairing a hydraulic gear system with hydraulic brakes.

That said, with groupsets, performance in shifting and in weight terms tend to override any minor compatibility or maintenance issues in terms of consumer demand and satisfaction. 

We were surprised to discover that Rotor’s UNO set-up creates the lightest groupset that includes hydraulic brakes - 417g lighter than a hydraulic equipped Shimano Dura Ace Di2 and 10g lighter than SRAM’s Red HRD.

Rotor is hydraulic-only, meaning there is no option for mechanical braking with the system.

That does not restrict it to discs, though, as Rotor has developed a hydraulic rim brake system in conjunction with Magura, similar to what was used by Cervelo on its P5 TT bike.

Rotor Uno front derailleur

Curiously, the UNO groupset breaks from tradition by removing the indexing from the shifter and instead placing it in the derailleur.

Since the development of Shimano's SIS shifter system revolutionised in 1984, almost all groupsets have based the indexing system in the shifter.

The UNO system’s ratchet mechanism at the derailleur is pushed into position by the hydraulic fluid to determine the position of the rear derailleur. Multiple up shifts are possible - up to four sprockets at a time.

An additional feature is the ability to disengage the rear derailleur. A simple flick of a switch drops the mech to the bottom sprocket on the cassette for quick and easy wheel changes.

First Ride

We rode the Rotor Uno with Q-rings and Rotor’s 2in Power crankset in the mountains near to Madrid. The system began with some stiffness, as it had been newly installed, but as the hydraulics bedded in it became smoother and lighter.

The shifting works on a similar model to a mechanical Sram road system, with one tap on the aluminium paddle lowering the gear, but a longer pull pushing the chain onto a larger and easier sprocket.

My very first impressions of the shifter was that it wasn’t working, as the lever shift felt alien to me – there was none of the expected feedback, that a mechanical system gives you.

It felt a bit like a mechanical lever minus its cable, in that there was very little resistance to make the shift, and such light action initially made it hard to discern if you were actually moving the derailleur.

I soon became accustomed to it, though, and it began to feel more and more intuitive.

Rotor Uno S-Works

The ergonomics also struck me. I liked the wide feel of the hoods, but was conscious they may be a little bulky for those with smaller hands.

At the front of the hood, the transition to the lever is a little harsh, as there’s a sharp gap between the two, which is a marked difference to the seamless form of Sram, Campagnolo or Shimano’s top-level hoods and levers.

It was a subtle issue that most riders wouldn’t notice, but I thought would irritate me over time.

Shifting perception

In terms of function I was very impressed by the feel of the single-lever operation. A key benefit of a hydraulic system is the inherent smoothness.

The lack of drag was immediately evident in the slick actuation of both the shift lever and the rear derailleur. It shifted positively through the cassette in a quick, decisive and quiet manner.

Shifting under load posed no problems either and the very defined indexing mechanism seemed to eradicate the possibility of missed or accidental half-shifts.

Rotor Uno shifter

The front shifting was slightly more temperamental, not helped by the ovalised Q-rings, which continually alter the chain’s height in relation to the derailleur.

Even the best of systems consistently struggle with ovalised chainrings, but in the case of the Uno it seemed that the front shifting was trickier under pressure.

It was hard to discern if this was a consequence of a less stiff derailleur or cage or possibly an inherent difference with the indexing system, as the hydraulics and ratchet mechanism seemed less capable to overshift slightly, something that is often needed in a mechanical system to solidly push the chain from the small to large chainring.

It was no serious problem, but I felt it required a significant drop in pedal pressure to make a smooth, reliable shift. 

On the brakes

Rotor Uno disc brake

Having worked in collaboration with German company Magura, Rotor’s brake system feels surprisingly mature for a first offering.

The braking was extremely impressive. The calipers showed no sign of rubbing, and offered plenty of modulation and power.

Interestingly Rotor is insisting on 160mm disc rotors, believing this larger diameter to be the best and safest option. 

Overall Rotor has certainly not disappointed, and rather than producing a ‘me too’ electronic or mechanical system, Rotor has clearly made a concerted attempt to prove that hydraulics are a viable and potentially superior option for groupsets.

That said, there is the added mechanical complexity of bleeding and working with hydraulic fluid to consider.

There are likely to be niggles and the aesthetics may be a little divisive. There’s no doubt that this is prepared to compete in the market, but with the entire system being built in Spain, we will remain excited about rolling upgrades to the system that may push it up to the level of the very best on the market. 

The Rotor Uno will be on sale from July onward, and will retail for an MSRP of €2499.

Buy the Rotor Uno from Tredz here

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