Test from the Rotor 1×13 group

With its 1×13, Rotor offers an original single chainring transmission system, which turns out to be the lightest of the current groups with disc brakes. The Rotor nevertheless imposes the montagand a specific rear wheel, and gear changes are not as smooth as the competition, despite using a hydraulic system.

By Guillaume Judas – Photos: Vincent Lyky / DR

The single chainring for cycling on route is a solution initiated by Sram in 2015, and widely adopted since then by all equipment manufacturers on the market for cyclo-cross or gravel. With a single chainring and 13 rear sprockets, Rotor offers an interesting alternative that almost competes with double chainring and 11-speed solutions., most of the time offering 14 different ratios (and not 22 as one might expect, given the duplication between the developments with the small and large chainring). As a result, The Rotor offers most of the advantagestagIt is a double transmission in terms of range and progressiveness of developments, but with the simplicity of a single chainring, and an interesting weight saving.

With four cassettes available (10-36, 10-39, 10-46 and 10-52) combined with a range of chainrings from 38 to 54 teeth, the 1×13 offers something for all tastes and all practices. Let us recall that the Rotor brand is primarily specialized in cranksets and chainrings, and that it offers a very wide range of teeth with round or oval chainrings. On our bike test, a 46-tooth chainring and a 10-11-12-13-14-15-17-19-21-24-28-33-39 tooth cassette offers the same gear range as a 51-39 chainring combination with an 11-31 cassette, but with the first six sprockets in sequence, better than the first five of an 11-28 or 11-30 in 11 speed. With a 50 chainring and a 10-36 cassette, the Rotor offers a development range comparable to that of a 53-39 and 11-28 combination., with only one missing gear in the range, rather towards the top of the cassette, where the gear differences are the least significant. From a technical point of view, the Rotor 13-speed cassette uses the Shimano HG 11-speed footprints, but with a 3 mm longer body towards the inside and a spacing between the sprockets identical to that of the 12-speed. The first 10-tooth sprocket locks partly on the outside of the cassette body, so that it maintains a classic diameter. The chain used is therefore identical to that of a 12-speed group, but the group requires the use of a specific hub.

Rotor group indicative weights

Comparison of development ratios between a 53-39 / 11-28 and 50 / 10-36 combination at Rotor 

Hydraulic braking and transmission

But the 1×13, now taken up by Campagnolo with its Ekar groupset dedicated to gravel, is not the only innovation offered by Rotor, since in 2016 the Spanish brand offered a groupset with a unique hydraulic transmission, instead of a cable or wire transmission (or wireless now for Sram and partly for Shimano). It is therefore no surprise that Rotor uses the same technology on its 1×13. Hydraulics at the forefronttagand to be completely waterproof between the handle and the derailleur, to not have a cable that risks seizing or breaking, and to not require recharging as with a battery. The indexing system is located at the derailleur, which prevents it from getting out of adjustment, and a push button on the mechanism is enough to move it to the right when the demontage of the wheel. This derailleur is equipped with a sort of clutch to keep it tight in position, so as to limit the risk of the chain jumping at the crankset.

Finally, in terms of weight, the system fully benefits from these two philosophies (single chainring and hydraulic derailleur) to appear as the lightest on the market among groups with disc brakes, with an average weight of 2379 g. At the top of the range, competitors claim 2442g for the Shimano Dura-Ace Di2 12-speed, 2516g for the Sram Red eTap AXS, or 2529g for the Campagnolo Super Record Disc. At 2577g, the Campagnolo Ekar in 1×13 speed, created more specifically for gravel, is the most comparable to the Rotor. It weighs 200g more, but still costs less. Because As the Rotor requires the use of a specific freehub body, it is offered for sale with different wheel options, or in 12 speed without wheels, since the groupset is 12 and 13 speed compatible :

• 12-speed kit without wheels (ready for later upgrade to 13): 1999 €
• 1×13 SuperLight Kit (carbon wheels): 3499 €
• 1X13 Kit 2InPower (2InPower power sensor and carbon wheels, like the model of test: 4499 €

Group prices can also be flexible depending on the chosen crankset., because Rotor obviously offers several models (Vegast, Aldhu, Aldhu Carbon) and power meters (INspider, INpower and 2INpower). The Rvolver rear hub pair or hub alone can also be added to the groupset. For our test, this is the top-of-the-range version with the power meter that we have tested. A fluid and nicely finished crankset, which also proves to be very precise in terms of power measurement.

For braking, the Rotor group uses original models Magwill be particularly efficient. Even if it takes a few dozen minutes to get to grips with the braking dosage, it is reliable and especially formidable in the rain. On dry ground, the noise is minimal, and friction during acceleration is almost non-existent, with two 160 mm discs. In any case, they are largely up to the competition.

Ergonomics reminiscent of the Sram Double Tap

In terms of ergonomics, the Rotor 1×13 groupset stands out with fairly large levers, with soft hoods that offer good grip. It's just a bit unfortunate that they don't seem to be perfectly glued to the frame of the lever, and that they tend to turn slightly in the event of firm manipulation. The brake levers are relatively accessible for average-sized hands, and they are adjustable. By lifting the top of the hood, we find a screw which is used to bring the brake lever closer.

The single gear change paddle – for the rear derailleur, therefore – is handled like the Sram Double Tap (mechanical), with a short push to lower a sprocket on the cassette, and a longer push to raise a sprocket. The rear derailleur is very precise, and never seems to hesitate between two sprockets. The lever operation is not as pleasant as with electronic derailleurs, and sometimes even less flexible than with a good cable system.. The feeling is more blurred when changing gears. On the lever, you don't really feel a clear engagement, since the indexing is integrated into the derailleur, and not the shifter. The "click" is barely perceptible here, especially when going uphill, and seems quite far from the perception of the fingers. To mount several gears on the cassette (two or three) you need a very large movement towards the inside, but not really natural. On the other hand, it is not possible to go down more than one gear at a time. After a few dozen kilometers, you of course end up getting used to the kinetics of the transmission, but it remains clearly less pleasant than those of Shimano, Sram or Campagnolo. The movement of the gear lever always seems a bit stiff in any case.

The lack of a front derailleur is an advantagetagand at the transmission noise level, which still proves to be smooth and quiet, even if it seems a little noisier on the two most extreme gears. Overall, thetagThe 10-39 cassette is correct, with however a little more development gaps on the last third of the cassette. This version seems to us more adapted to the practice of gravel, or at least to the high mountaintagonly on simply hilly and windy courses.

The specific hubs, here delivered with very good quality Enve carbon rims, are very fluid, and they feature a quick-engagement freewheel that helps the bike's responsiveness. They look very high-end, although we don't know much about their durability.

The fact remains that the limitation to the use of these special hubs can be a hindrance to the choice of this group, which also leaves us a little hungry. Certainly, The 1×13 Rotor is lightweight, and allows the montagand really high-performance bikes, under 6,8 kg with disc brakes, with simplified transmission, and a range of developments likely to cover most needs. It also has the merit of being truly original, and of resolving most of the compromises necessary with a single chainring. But The gear changes just aren't as smooth and enjoyable to use as the competition, especially at this price point.

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