26 March 2009

bikefix Exclusive Review: Rotor Q-Ring chainring

Nearly since its invention, clever (and less so) individuals have been looking to improve on the most efficient form of transportation known to man. While some have been technologically driven (lighter, stiffer, stronger frames & components, more efficient seals and bearings), others have sought efficiencies in the way in which the human body interacts with the bicycle. As anyone who’s sat in an uncomfortable (but stylishly angular) chair can attest, the human body tends to resist simple geometries like lines and circles. While much of the traditional bicycle’s elegant simplicity comes from simple geometries such as round tubes, straight spokes and wheels and straight spokes and frame elements, as designers learn more about the materials and forces involved, these elements evolve into ever more complex geometries. Case in point: Rotor's Q-Ring chainring.

Spanish company Rotor came to the bicycle market several years back with a cleverly complex crankset designed to offer the rider’s leg less leverage where it is strongest (when the crankarms are roughly perpendicular to the seat tube) and speed it past the ‘dead spots’ where it has the least to contribute toward forward movement. Unfortunately, as is often the case, clever here translated to heavy and expensive. Despite the high cost (this was before $500+ cranksets became commonplace) and weight, a fair few riders adopted the RS4 and claimed not only perceived benefits but also reduced times and (more interestingly) reduced fatigue and lactic acid buildup. Realizing that their complex (and, let’s face it, ugly) crankset was unlikely to gain widespread acceptance, Rotor began work on what would become their Q-Rings.

The slightly squashed-looking rings (in my case a 34t) has a smaller radius (lever arm pulling the chain) when the cranks are parallel with the seat tube and a slightly longer effective radius when the cranks are perpendicular to the seat tube. The transition is smooth, much like the variation in their ability to put down power through the pedal stroke. Being just chainrings, the Q-Rings are unable to change the position of one foot relative to the other as the RS4. They do, however give the legs more leverage where they can use it and make things easier where they can’t. [Note: this is the opposite of what Shimano's much-ridiculed Biopace chainrings did] The benefits? A claimed reduction in fatigue and lactic acid buildup, increased power and happier knees- all of which are backed by the ever-popular (at least in advertising) university studies. I ran into the guys from Rotor USA at Interbike this year and noticed a singlespeed mountain bike in their stand. While I was aware of their product, my assumption was that a non-round ‘ring wouldn’t work without a derailleur to take up the slack as it rotated. While Rotor’s Q-Rings do change the effective chain length through their rotation, it turns out that it was by less than one might expect and that the chain is slackest at the points where the rider can’t put power down and is rarely descending over rough terrain (with the crankarms perpendicular to the ground). As curious as I was about the company’s claims, the not insignificant $95 per chainring cost put me off the idea- at least for a while.

This past December, with my training for February’s 24 Hours in the Old Pueblo not going as well as I’d hoped (does it ever?), I found myself wondering about what a Q-Ring could do for me. On long rides, the claimed 4.1% increase in power output sure sounded good, as did the 9.1% reduction in lactic acid levels. I decided to bite the bullet and give Rotor a call. Within a few days, a package from Colorado Springs landed on my doorstep and was opened to reveal a nicely machined and lightweight chainring. With a lot of Siamesed bolt holes. As comprehensive as Rotor’s instructions were, they were a bit confusing to me (does “better for sprinters” mean that a setting would be better for those who were already sprinters or those looking to become sprinters?), and I resolved to mount the road compact middle ring (110bcd) to my single speed in its middle position (of five sets- hence the multitude of bolt holes) and give things a go.

On the bike, the Q-Rings felt odd. That nice, round, fixed-gear induced spin? Forget it. With the Q-Ring, the riders’ legs accelerate (relative to a round ‘ring) at the top and bottom of the stroke and slow at its midpoints. While pedaling with the Q-Rings felt choppy and odd at first, I adjusted within a few rides and haven’t noticed it since- except when coming back to the Q-Ring after several weeks on round chainrings. After about a dozen hours riding the Q-Rings in their middle position, they felt unnecessarily odd and hard. On Rotor’s recommendation, I purchased the same size chainring as I was used to, and the reduced leverage on the downstroke made it feel like I was pushing too tall a gear. Once (or twice) again, I sat down with the instructions, deciding to move the Q-Ring one spot to its slightly delayed #4 position. Back on the bike, the difference was immediately apparent. By moving the lowest leverage spot a bit further down in the pedal stroke, it felt like I could stay on top of the gear a bit better (with my feet carrying a bit more momentum, maybe?) and I started to feel much better about my purchase. The non-round ring meant that I was effectively pushing a 36x19 (on a 29er) where my legs were stronger and I certainly felt one or two teeth faster, without additional effort. Even better, I felt like I was recovering more quickly. Of course, this could also be the result of my wearing compressive travel socks or eating better than in years past, but there were times when I was actually shocked at how good I felt in the days after a particularly hard ride. I also felt fresher at the end of hard rides than expected- though that change wasn’t quite as dramatic.

What about the race? My plan (for those of you who know the race) was to alternate double laps with my duo partner, giving us each some good eating and recovery time, especially at night. Talking to others who did well as duos, I’m not sure if this was the best strategy, but we gave it a go. As in years past, I planned to start with a 34x19 and swap out to an easier 34x20 after the first or second double lap. Feeling good after my first double, I opted to keep the taller gear for the next thirty miles. This was my mistake. Rather than spinning happily along, I wound up mashing a too-tall gear with legs that weren’t up to it. As a result, my second half wasn’t what it could have been- but it could have been far worse.

Do Rotor’s Q-Rings deliver as promised? That’s hard to say. On the single speed, I have to say that I like mine. There are so many variables in mountain bike racing (especially endurance events) that it’s hard to trace changes in one’s performance to a single factor- let alone a single component. It feels to my uncalibrated legs like the Q-Rings’ benefits lie mostly in shortening the recovery time required after hard rides. I’d certainly put $95 towards a Q-Ring before spending the same just to save weight- the returns just seem to me that much better. The adoption of Q-Rings for 2009 by Cervelo's new "TestTeam" lends a bit of weight to my seat-of-the-pants assessment. Best, cost excepted, I can’t find any reason not to try Q-Rings- there’s no compromise of handling or durability, which puts them ahead of many other ‘upgrades.’ For those in particularly competitive classes, where the top ten finishers are tightly spaced, the investment may well be worth it. I certainly don’t see myself taking mine off any time soon.

marc

www.rotorusa.com

4 comments:

CJA said...

what about a long term report on the carbon cranks?

bikefix said...

CJA,

Have a look here... Still going strong! http://www.bikefix.net/2008/09/bikefix-review-update-truvative-rouleur.html
mb

Anonymous said...

And a year later? Are you still running them?

bikefix said...

A year and some on, I'm still riding the Rotor on my single speed. I like how it rides on the single speed and hardly notice it any more. I wouldn't mind giving a set a pair on the road bike to see what they feel like with more normal, high-cadence pedaling though.

marc