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First ride review: Rotor 1x13 hydraulic groupset

26 Jun 2019
Verdict:

We’ve finally tested Rotor’s hydraulic 13-Speed groupset and we’re pleasantly surprised, aside from a few niggles

Cyclist Rating: 
For 
Incredible range, nice chain retention, very light, reliable shifting
Against 
Pricey, shifting lacks compared to electronic, 13-speed needs Rotor hub

After much anticipation, we’ve seen our first road-worthy sample of the Rotor 1x13 hydraulic groupset at Impact Sun Valley in Idaho, and a first blast on the road has proved the system to be impressively finished and well thought out.

Rotor has thus far been a tad elusive with its hydraulic groupsets. To clarify, this groupset does not use mechanical force or electronics to shift, but instead the tiny tube that feeds through to the rear derailleur is a hydraulic cable that uses mineral fluid to actuate the movement of the rear derailleur, in a similar way to the actuation of pistons in a disc brake.

This groupset was first shown at Eurobike last year, and has taken some time to reach the market. Similarly the original hydraulic Rotor Uno was tested by journalists and teased by some pro cyclists in 2016, but it never seemed to take off on OEM spec or as an after-market option. That’s probably because it suffered a handful of niggles.

Predominantly, the front shifter proved to be a slightly troubled design. When I test-rode the groupset myself, I put the flaw down to a lack of overshift to push the chain onto the large chainring, which electronic and cable systems naturally offer. Given the binary dynamics of hydraulics, it seemed like a tough problem to solve.

Removing the front shifter sidesteps that problem altogether, and by introducing 13 gears Rotor has also offered a solution to the problem of a lack of gear ratios that a 11-sprocket system suffered. 

We tested the 1x13 on a Mosaic titanium bike equipped for gravel riding

Rotor argues that with 13 gears, it is only one short of the truly functional range of different gear ratios offered by a conventional double chainring setup – owing to the overlap between small and large chainring gears.

Rotor also argues, and I am inclined to agree, that as most riders don’t shift between large and small chainring to achieve the smallest step in gearing possible when in the middle of the cassette, that the full range of gearing steps is not relevant. Or to put it another way, a rider won’t shift from big to little ring and then up three gears on the rear in order to seek the smallest change in gear inches. They will generally just shift on a single chainring to keep in the right gear, and then use the front derailleur to make available an easier or harder selection of gearing choices overall.

You can see the full reasoning behind the gear ratio arguments on Rotor’s website, but below is an illustration that lays out the gear ratio differences between a 2x11 system and a 1x13. It also demonstrates that the system offers a greater overall range than the vast majority of 2x11 systems.

For me, the idea of ditching the front derailleur has always held enormous appeal – in terms of chain tension (with a clutched derailleur), frame design, weight and maintenance. So I was really excited to see how the range and gear steps on offer by Rotor’s 13-speed system would cope on gravel and on the road.

Rigid start

As with the Rotor Uno groupset, I was initially a little struck by how stiff the gear shifter felt. In both cases I had to check that there was no obstruction and then use a level of force that felt a little unsettling.

Whether I simply adapted to the force of shifting subconsciously or whether shifting became easier as the hydraulic fluid warmed I can’t be sure, but it wasn’t an issue I noticed later on. Rotor also points out that you can adjust the tension of the shifter, though reducing the tension does make for a less positive sensation in shifting.

Similarly, because the initial shift was a little stiff, it took me a while to push through the up-shift and realise that the derailleur offers a multi-shift of up to four gears at a time.

Once I became used to the shifting, the Rotor 1x13 really grew on me. As there's no danger of cable stretch with a hydraulic system, the shifting seemed to be robotically precise in each position. Shifting was fast without being agricultural in terms of either force and speed.

That said, I jumped from the Rotor 1x13 straight onto a new Sram Force AXS 1x12 eTap setup, and it brought home how much more capable and finished electric gearing remains compared to Rotor’s hydraulic offering. Not that the Rotor system is bad, but it’s easy to forget how much electronic shifting has come on. 

As strange as it sounds, though, shifting isn’t everything when it comes to groupsets. The real appeal of the Rotor 1x13 is its versatility.

On the open range

Firstly, it’s worth reiterating that Rotor’s 1x13 system offers more range than most standard 2x groupsets.

With a 46-tooth front chainring, my 10-tooth rear sprocket offered substantially more gear inches than a 50-tooth compact chainring with a 12-tooth sprocket. Meanwhile, the 39 sprocket has less gear inches than a compact 34-tooth chainring and a 28-tooth sprocket. 

What that means is that when I found myself at 54kmh on a shallow descent, I was still able to pedal at a reasonable cadence to deliver power, while at the same time on a very steep gravel section I was happily keeping cadence up and over 15% inclines.

Riding over rough gravel, the chain retention was also fantastic. The clutch system within the derailleur is most likely to thank for that. For me that opened possibilities for a wide range of riding, and I also meandered onto some singletrack, on which the Rotor 1x13 seemed like a hugely well-equipped option.

Now that’s no different to rangey 1x systems with 11 rear sprockets, but the 1x13 prides itself on an increased level of gearing options by comparison.

In that sense, I was pretty impressed with Rotor. Since it has spaced the lower end of the cassette relatively close together and then increased spacing as the gearing increased, I really did not notice big jumps between gears. 

Rotor offers cassettes with a range of either 10-46 or 10-52, the latter aimed predominantly at adventure and mountain biking, proving a really incredible range overall but more noticeable steps along the way.

We tested the Rotor 1x13 on road and gravel in the mountains of Idaho

As Rotor’s own marketing suggests, the gearing jumps on the smaller sprockets is very much in step with the changes on a double-chainset on the lower half of the cassette. As the gear gets lighter I didn’t notice the steps increasing, largely as at this point I tended to be hunting for easier gearing anyway.

But the 13-speed Rotor option has a big drawback.

Why 13?

While the 13-speed cassette offers the greatest range of gears, it is not available on just any setup. 

The cassette actually uses 12-speed spacing and a unique Rotor hub to make space for the 13th sprocket. That is good in terms of chain width and strength but obviously rules out the use of after-market fully built wheels. 

That’s one reason why a complete groupset price comes in fairly high for the 13x spec, with some retailers offering the group for over £3,000 with a 2inPower power meter crank and a set of wheels. That’s a hefty price for an extra sprocket.

Rotor does offer the system as a 12-speed offering, with 11-36 or 11-46 options, at £1,750. This will no doubt be the favourite for roadies. But 13 sprockets are unique to Rotor, and the unique selling point for this group. So with a 12-speed I would be tempted to weigh up the advantages against Sram Force AXS 12x eTap.

Then there’s also maintenance issues such as the hydraulic bleed that will be needed for service. That needs to be done once per year according to Rotor. I wouldn’t be surprised if – so long as it is set up and maintained properly – the system lasts longer without issue, though.

That said, the advantage of weight does remain, as this group comes in at a claimed 1,785g, which is substantially lighter than Sram Force 1x (claimed 2,213g) and even Sram Red AXS 1x eTap (claimed 1,913g) and of course all 2x Dura-Ace options.

Another neat advantage is the ease of chainring adjustment – the chainring can be switched with a single 8mm allen key adjustment. That means that the overall ratio can be changed very quicky to suit road or gravel riding more specifically.

As with any groupset, the real test will be the long-term performance of the group. We expect a full test sample to arrive at Cyclist HQ soon, where we can look at the long term performance.

For now, though, we’re impressed at the direction that Rotor has taken, and we’re excited to see whether a 13th sprocket could be a favourite for gravel riding, and the beginning of a viable option for high-performance road riding.

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