Featured Image

Review: Rotor R-Hawk Crankset

Technology comes full oval

Recently, a trailhead passerby asked, "How do you like those cranks?" The question got me a-thinkin’. Obviously an integral mountain bike component, cranksets are tricky to review or describe. When performing properly they tend to disappear beneath the rider as they concentrate on the terrain ahead. I wanted to respond with, "So far so good. How do you like that seatpost clamp?"

Spanish component manufacturer, Rotor, has carved out a niche among endurance cycling genres with their power meters, cranksets and perhaps most notably, oval chainrings. Released earlier this year, the Rotor R-Hawk crankset marks its foray into the all-mountain category. And the crankset is brimming with interesting features. The crank arms utilize a hollow 7055 aluminum alloy construction which are bored-out and machined in-house in their Madrid facility. In an era where every 18 months cycling brands seemingly institute engineered obsolescence, otherwise known as new ‘standards’ in bike design, budget-minded or practical riders may appreciate the R-Hawk crankset's modular construction. A modular design means the crank arms are independent of the axle and chainring, similar to commonplace three-piece cranks of days past. Both arms can be removed from the axle, which allows the same crankset to be easily updated or modified to accept Boost, super Boost, double-secret super-duper gluten-free Boost, or likely many future frame spacing configurations by updating an axle and its spacers rather than an entire crankset. For $349, you score the R-Hawk setup including crank arms, axle, bottom bracket, protective boots and chainring. Riders looking to be matchy-matchy can swap the stock black arm protectors with one of seven colorways.

The R-Hawk cranks are tightened down with 8-millimeter bolts on both the drive and non-drive crank arms. I've been running the Absolute Black oval ring chainguide with few chain retention issues. As you can see, the trails were quite messy this past weekend.

Rotor is known for their oval Q-Rings. Although not a new cycling technology—I ran [rather BMX-dad implemented] an oval Shimano Biopace chainring on my 10-pound BMX mini when I raced as a wee Ryan in the '80s—Rotor claims their Q-Rings simulate a higher gear at the point of maximum force and the most productive area of the crank rotation. In the rotation ‘dead spot’ where we exert less force, the simulated smaller gear makes quicker work of spinning through that portion of the crank rotation. Rotor says the implementation of their oval design has the exact opposite intention of the Biopace rings of yesterday.

Weighing in at 585 grams for the crank arms, plastic boots, and a 32-tooth chainring, the R-Hawk crankset might not be the first choice for the picky gram counters out there. (The claimed weight for the crankset and axle is 665 grams.) However, I've been running them on my mid-travel 29er for nearly six months and have found the R-Hawks to be nothing if not stout and reliable.
The durability and versatile nature of the modular construction is notable, however, the heart of the R-Hawk crankset is the oval Q-Ring. Despite a few brands now offering aftermarket oval chainrings to fit most cranksets in the sport, it had been many years since I'd ridden an oval ring. Since then, a lot has happened in both cycling technology and to my body, which allowed the Q-Ring to serendipitously influence my riding experience.

The OCP system attaches the ring to the spindle, not the crank. Repositioning the ring requires simply removing the arm, clocking the ring to your desired position, and tightening it all back up.

During my time on this spinning rock in space I've unfortunately endured nearly a dozen reconstructive knee surgeries; including four ACL reconstructions (twice each knee), plus numerous other ligament and meniscus procedures mostly occurring in my collegiate ice hockey and football days. Similar to how a paperclip can only be bent in the wrong direction so many times before it stops functioning properly, my right knee is the same way. Since I was 22 years old, and due to no fault of my own, I've had less than 60-percent range of motion in that leg. Realizing I'd never again be able to run or really even walk without a limp, cycling became the only activity which I could still somewhat participate in. Although the extremely limited range of motion has never allowed my right leg to keep up with the desired pace of my left, I've just played with the cards I was dealt and managed the situation the best I could.

After six months of regular abuse, the R-Hawk cranks still perform like new. Regularly checking the 8-millimeter axle bolt is recommended, but it has rarely come loose.

When pedaling with a standard round chainring, my right leg often feels hung-up when the upstroke transitions into the downstroke, or as Rotor describes, moving into the ‘power position.’ Coincidentally, the problem area in my range of motion very much intersects with the dead spot feeling Rotor's Q-Rings are designed to reduce. Obviously, Rotor didn't design their Q-Rings with my bolted-together, cadaver-tendon-clad legs in mind, however the Q-Ring's performance has become a much-appreciated benefit. During long seated climbs, the virtually decreased gear ratio of the oval ring in the dead spot is noticeable, and ultimately allows me (and I presume those with functional joints) to more easily initiate the power position of the next rotation. Concerned this could all be in my imagination, I did little online forum browsing and have read similar accounts of how the Q-Rings have reduced knee pain in riders of all disciplines for a variety of reasons and scenarios. Reduced pain and improved range of movement in my situation aside, I found the oval ring can offer advantages when clip-clopping up very steep and technical climbs. On a mountain bike, we can find ourselves only a quarter-crank rotation away from tipping over, so having a chainring that helps a rider more easily get their cranks into the power position is a welcome enhancement.

Rotor's rings have 10-percent ovality, which they feel is ideal for trail riding. The narrow-wide chainrings are designed to work with all 9, 10, and 11-speed groupsets. I've been using the crankset with a 12-speed X0 Eagle drivetrain.

Another differentiating factor with Q-Rings is the ability to adjust the oval position by aligning it in a rider's optimum power position along the splined axle, a feature conveniently described by Rotor as Optimum Chainring Positions (OCP). Though brands like Rotor have elevated the oval ring to a high science, there’s still no one “best” shape. Even within Rotor’s lineup, there is variation. Different cycling disciplines can benefit from use-specific chainring shapes. For example, a triathlete who's primarily seated may want the oval ring in a different power position than a mountain biker who shifts frequently between standing and seated and is constantly shifting weight and upper-body force to maneuver over varying terrain.

Are you down with OCP? Rotor's axle and oval chainrings are laser etched with indicators for proper chainring placement. I primarily ran the ring in the recommended position. Photo courtesy of Rotor.

So why, within the singular discipline of mountain biking, would one need to diverge from Rotor’s optimal position? First, there’s nothing singular about mountain biking. Some clip in, some ride flats. Some are spinners, some are mashers. Some ride hardtails, others are normal people who ride normal bikes. I, of course, started in OCP’s middle position “3” and stayed there until I got accustomed to Rotor’s particular ovality. Yes, that is a word. Position 4 clocks the apex of the oval forward by 4 degrees. Technically, it’s by 184 degrees, because that apex is offset between two of the 45 splines, which means fine adjustments require a half rotation. I theorized that position 4 might work well with my taste for steep seat angles and aggressive pedaling. But I could barely tell any difference until I jumped to position 5, which was noticeably too much. Especially when pedaling rapidly, the force fell away too early, and it disrupted my cadence. Conversely, clocking the ring all the way back into position 1 got me hung up in technical climbs and made the bike feel like it was in a harder gear than I had ordered until the beginning of my power stroke.  I ended up back in the made-for-the-masses position 3, but you may not. That’s the benefit of OCP. If you’ve transitioned into the oval ring concept happily but not yet smoothly, you’re likely to find your flow somewhere in those settings.

For as ambiguous as traditional cranksets often feel, the Rotor R-Hawk has been extremely durable and maintenance-free, while the Q-Rings delivered on the promise of reducing the dead spot feeling in the crank rotation. And as I think back to that passerby’s inquiry about the cranks, maybe there is more to these than a seatpost clamp.

Rotor Bike Components

Related:

Sea Otter 2017: Rotor, Manitou, Terrene and Deity

Sram Releases Eagle Oval Chainrings

AbsoluteBlack launches spiderless 32T oval chainring