A LOOONG ESSAY About Pedal Stroke, SpinScan, and Rotor Q and QXL Rings...

QXL Crank Position 3 170mm Rotor Crank

Those of you who know me, know that at heart, I'm a Geek. A total, unapologetic, Cycling Geek. I remember when I ran my last Cross-Country race as a runner, way back in 1992. After it was over, I remember thinking "This far, and no faster. I will never be any stronger than this as a runner." And that next week, I emptied out my locker at Davidson College, completed my transfer to Montana State, and dedicated myself to becoming the best Cycling and Mountain Biking Coach I could possibly be. 

The difference between cycling and running, for me, is that there will ALWAYS be some new challenge, some new effort, some new move or equipment or style, or strategy, and it will perpetually keep me interested in learning its' mastery. When I ran, well, I ran. I ran intervals, and I cycle intervals, but it's just not the same. New shoes won't make me faster, and they won't prevent shin splints. However - new tires and tubes on a bike can make a difference, albeit subtle. Running singlets wick sweat and repel UVA rays, but Cycling Kit can make or break a day, depending on how it's stitched, what fabrics are used, how thick the chamois is, and how much necessary stuff you can place in a back pocket. Runners get excited about shoelaces. Cyclists get excited about BOA cables and sole stiffness. Basically, there's only so much that a runner can do to get faster, and the strategy for running is to basically run at a pace that's sustainable, while training at paces that are unsustainable, while cyclists have an endless number of variables that they can put to use to get better and improve. Cadence, kit, fit, gear, slope, speed, wattage, even air density is more important for a cyclist! There's just SO MUCH MORE to TRAIN!

So with that bit of historical perspective, I'll give some more anecdotes and then we'll get in to the meat of the discussion today. 

I move to Montana, start racing mountain bikes, and quickly realize that I'm not going to get any faster if I don't train in the winter. So, in 1995, I bought my first CompuTrainer. I still have it, somewhere, in my collection. But it's not the fact that I bought it - it's the fact that I actually USED it, in it's Nintendo-esque sort of way, from November through Easter of that winter, that made the difference. The programming was just pitiful, but what I ended up doing was the following.... 

I set up my mountain bike in a barn, next to a pellet stove, and I would work out in there, staring at these colored bars, which represented the Torque I was putting in to the pedals. RacerMate called it "SpinScan", and to this day, it's still a source of debate in the cycling community. The SpinScan graphically reveals the "Net Torque", or the amount of positive and negative drag placed on a pedal as it goes forward through a revolution. There will always be positive torque, and there will always be negative torque. When they're equal, the pedal and crank are stationary. But the argument that RacerMate made was the following - by studying a rider's SpinScan, they could make position adjustments, and also neuro-muscular adjustments, to sort of turn what was usually considered a 'Piston'-like stroke, with more power in the down stroke, and a definite lack of power in the up-stroke, to something more like a 'Turbine', where net torque was more uniform throughout each revolution of the cranks. 

Now, before I go further, I have ONE BIG CAVEAT ----- There is NO, ZERO, NONE, Scientific or Empirical Evidence that what I'm about to say has any validity whatsoever. We DO have anecdote, but to this day, RacerMate has NEVER commissioned a study with an objective 3rd-party laboratory, that PROVES that a 'Round' Pedal Stroke is 'BETTER' in any way, than a traditional pedal stroke. In Fact, the ONE STUDY that was done to determine which was better, lent itself towards the more traditional piston-style pedal stroke, being more powerful overall, and yielding a higher average power output. But that was one study, done over 20 years ago, and it did NOT measure much more than power output over a time/distance. BUT ANECDOTALLY, riders have claimed for two decades now that when they pedal circles, they 'feel' more economical, don't move around as much, feel like they can raise their cadence a bit, and 'spare' muscles, especially among triathletes, for later stages. I don't know, and I don't have the ability to tell. But in my own humble experience, well... let's get back to the story. 

I spent that winter training, not really knowing what Threshold Power was, or anything, really, but I did end up getting a SpinScan Count up in to the 90's. What's that? Well, if a ZERO is a perfectly Terrible Pedal stroke, in other words, not a pedal stroke at all, and a 100 was a Perfectly Even Pedal Stroke, then having a Pedal Stroke Count in the 70's to 90's SEEMED to be pretty good. I trained myself, hour after hour, to change the way my pedal stroke looked and felt. The sound of the CompuTrainer changed from a 'Whom Whom Whom Whom" sound to a 'Whommmmmmmmmmmmmmm" type sound. And my average power output grew. I added slope, slowed down my cadence to mimic the real world, and kept working on training my brain to generate those 'better' values all the way around the pedal stroke. After about 15 weeks, here's what happened...

I got to several early-season mountain bike events, and like always, my bike handling skills were just mediocre at best. But it was the CLIMBS where I really ended up excelling! I'm convinced that my circular pedal stroke helped me climb faster and more efficiently, and helped me HOLD TRACTION on slopes where I might otherwise have slipped, and forced a dismount. The trend at the time was to create mountain bike tires that were 'Semi-Slick', and while it made you faster, it also increased your chances to slip if traction wasn't JUST RIGHT. But, with my brain trained, I really became a FAST climber, and while I didn't win anything, I was consistently in the Top 5 in my category, and enjoyed the racing. 

Fast forward to the New Millenium, and SpinScan gets an Update. Now, instead of looking like this.... (no, this is not a joke...)
TV Color Bars - Anyone Remember These after "The Late Show"?

It ended up looking like this....
Comp CS 1.6 Image Coaching Software CompuTrainer RacerMate

Now, this made a LITTLE more sense, graphically. The light-colored bubble represented the "Net Torque", and the graph behind basically meant that the right side was a composite of 1 o'clock on the right pedal, as well as 7 o'clock on the left pedal. 2 o'clock also had the negative torque effect of 8 o'clock, etc. There was also a little red thingy called an "ATA", or "Average Torque Angle", which basically showed where on a crank pedal stroke, a rider was putting out the best torque, and since torque is related to power, you could further train your brain so that your pedal power was not only 'rounder', it also was aimed closer to 90 degrees, which makes sense in a crowbar-sort of way. Try pushing down on a crank when it's at 12 or 6 o'clock, and... nothing happens. Pedal between 2 and 4 o'clock, and the wheel moves. Furthermore, try pedaling with just the trailing part of the leg, when the crank is between 8 and 10 'clock, and while the crank will move, it's just never going to have the power that you get when you're using your glutes and quads to force that bike crank down at the opposite position. It's muscle mechanics and bicycle positioning. It's not easy to explain, and honestly, I'm about to make it a little bit MORE difficult. BUT HANG ON. 


From 1995 until roughly 2002, I trained with SpinScan in my off-season, and learned how to train my brain to fire my muscles so that I had a GREAT-LOOKING SpinScan, and Average Torque Angle (ATA). But honestly, not too many, in fact, NONE, of my clients, had the time available, the energy to commit, or access to the equipment, that was necessary to even attempt to train for this. And again - WE DID NOT AND STILL DO NOT KNOW WHETHER A CIRCULAR PEDAL STROKE IS TRULY "BETTER" than a Traditional Pedal Stroke. BUT, with SpinScan, we CAN get an idea (finally), of what a Pedal Stroke "Looks" like, to some degree. So, with that in mind, I began to notice - MOST of my clients had what I would consider to be pretty ugly pedal strokes! They tended to have these 'morphing orbs' that resembled peanuts at best, and insect bodies at worst. They had Average Torque Angles that were 10 to 20 degrees below 3 o'clock. It looked like the majority of them were just PURE mashers, with no real regard to the nuances of what makes a smooth pedal stroke. And unless they were willing to completely relearn how to pedal, and spend HOURS with a professional bike fitter to help them get the right angles of leg extension and crank length, torso posture, etc. it was just TOO hard to even attempt it. 


Q Ring Animation Rotor Q Ring Well, nuts. It won't animate. 

Rotor was different. It was a company, founded by two passionate cycling geniuses, who realized that there WERE ways to make cyclists more efficient AND powerful. They were Spanish, they were specialists in metals, they were engineers, and they looked at things differently. 

Their first foray was an entire bike and crank gearing system that had the trailing crank on each revolution, move more quickly than the crank on the down-stroke, so that the 'Dead Spot' was minimized. IT WORKED.... But it was EXORBITANTLY EXPENSIVE, and it required AN ENTIRE NEW BIKE!

The Original Rotor Crank System, Complete with Accompanying Frame!

So.... in the spirit of innovation, they developed and entire crank system that fit inside a modern bottom bracket! This was less expensive, and it's where I jumped in to the game, buying several sets and trying them out. I still have the blog post about it somewhere, but suffice it to say that I was impressed with the idea, but not with the production execution, which was still bulky, heavy, and required a penalty in watts from internal drag. I called Spain, I tried my best to speak my broken Spanish with Pablo, the CEO, and together we came up with ideas to lessen drag and weight, but eventually, I backed out as crank-based power meters gained popularity. 

But Rotor re-acquired my attention when they released the perfect solution, Q-Rings. Q-rings were oval-shaped chainrings that focused not on producing a more circular pedal stroke, but instead focused on giving the cyclist MORE POWER at the point in their pedal stroke that already HAD the most power! Again - instead of trying to make a circle out of an oval, they basically EXTENDED OUT the oval! Furthermore, if you were optimal at 100 degrees on a pedal stroke with your Torque, you could change the angle of the chainring so that it actually hit closer to your power pedal position! 

I was instantly hooked, and began buying and installing these on my bikes. I can't really credit the rings for any wins, or anything, but they definitely showed an increase in my power output at certain positions on the power stroke. I did read up on one study (which I cannot find any longer), that showed how riding at Position 4 out of the 5 possible positions available could increase the RATE at which a rider could accelerate in a sprint, to Maximal Power, but honestly, most of the focus was on the ability to give my clients and myself a bit more power on the down-stroke, and when climbing. The rings weren't overly popular, and there were some shifting problems, but still - it was a small improvement that was felt more so than actually witnessed through a power meter. 

But I kept using them, and tinkering with them, and staying in touch with the developers and their American Counterparts in Colorado Springs. Rotor as a company grew, began offering many other high-quality products, and they obviously continued to innovate on their core items, which were Ovoid Chainrings. They abandoned the RSX4, introduced their own power meter, then another, and then ANOTHER, created an extraordinarily stiff and light crank in numerous lengths, and just kept at it. Finally, in 2013, they released an updated Q ring, called the QXL, which took all the evidence and testimonial from the previous DECADE, and put it to good use. It's more oval-shaped, in a unique way, and I just HAD to try it out.


I'm going to display a number of images and videos, and I'll let you decide, but I'm pretty happy with my small results, and I have an offer for anyone who wants to try it at the end of this, what is probably my longest post in YEARS. 
Coach Wharton with QXL's in Position 4
Okay - This first image is me, riding my QXL rings in Position 4, at a 0% slope. I'm using one of my latest CompuTrainers, with a Hockey Puck Cadence Sensor mounted directly at the 6 o'clock position on the crank. I have no idea if this matters or not, but I wanted to stick with consistency, and there is a lot of debate about SpinScan in regards to mounting the cadence sensor on a rear chainstay that is not directly at the 9 o'clock position. So with that in mind, we'll go with the left crank at 6 o'clock and stick with it. The graph tells you one thing, but really, just look mostly at the darker box on the right. My SpinScan is pretty good at a 78 and 80, making an average of 79, and my 'ATA', or 'Average Torque Angle' is at 97 degrees on the left, and 95 degrees on the right. Again, this is at Position FOUR on my QXL's, which are the most radical of the ring offerings in Rotor's range. This was what was on my bike before I messed with anything.

Now, Let's see what it looks like when I go to round rings....
Richard Wharton Round Rings 0 percent slope
The watts and cadence of this image are not completely the same, and Christie O'Hara, the chief researcher at Rotor, urges me to make sure that things are more consistent, but I was one-man-banding it when I did this, and it's hard to run "SnagIt" while using RM1 software, as it is. However, what you can see is that my 'ATA' trended closer to 90 degrees, and my SpinScan values were a few points higher. What does this mean? Well, it means that my overall pedal stroke on round rings was 'Roundier', and my peak power occurred closer to the area where I would have the strongest 'Lever' on my crank, which again, is 90 degrees. I do still have a dimple on my SpinScan Curve on the left and right legs between 1 and 2 o'clock, telling me that I need to work on my pedal stroke if I want that extra smoothness as I transition over the top of each revolution. 
Rotor QXL Rings at Position 1 Richard Wharton 0 Percent Slope

Now, the next thing I did was a little radical. I wanted to see just how different the pedal stroke looked when I rode my QXL rings in Position 1. So I unhooked the bolts, adjusted the rings accordingly, and cinched them back down. WHAM! Check THAT out! I have a MORE ovalized pedal stroke, my ATA rises ABOVE 90 degrees, and the 'Roundiness' of my SpinScan drops significantly. Honestly, the oval shape is something that is more indicative of most of my clients in the studio, but it's canted more along the 100 degree line, and not 70 degrees! ATA at 84 vs 95. Yikes!

QXL Position 2 Richard Wharton 0 Percent Slope
So, once again, I dismount, remove the chainring bolts, and slide down to Position 2 for the QXL's, reset the bolts, and then get back on the bike and..... Have a look at that. My oval, honestly, looks a lot like the QXL chainring itself. My SpinScan value is the lowest yet, but my ATA, especially on my right leg, is about as close to 90 degrees as you can get. I'm not sure what's going on with the ATA on my left leg, but I suspect it has something to do with cleat position, or where I was sitting on the saddle, etc. But again - take a look at the shape of the Torque Curve, and take a look at where the red ATA line sits in conjunction with the bulge. I THINK this is the purpose and location for the claim that Q Rings and QXL Rings can make a difference in a pedal stroke. I THINK that holding this position out on a flat road, MIGHT, just MIGHT give me a power advantage, that I can quantify. I'm going to leave them there for a month or two, and then try them at another position, but again, think about it - you want the MOST power at the point of GREATEST LEVERAGE, and on a bicycle crank, that occurs at 90 degrees. You want the LEAST resistance at some point where your leg strength is weakest, and for most of us, that coincides with the 6 o'clock and 12 o'clock positions on the crank. So, with a LOT of work, and study, I THINK I've found the Optimal Crank Position, or as Rotor calls it, the OCP, for my legs at this time. 

Just to make sure, I actually put both rings on Position 2, and ramped the slope up to 7%. Mind you - I did NOT raise the nose of my bike up accordingly, but I WILL TRY IT, with an ANCIENT piece of equipment that I have stored away in a shed somewhere. Long story short - here's the graph, and I'm pretty happy with it. 
QXL Rotor Rings at 7 percent Slope Position 2 Richard Wharton

SO.... What have we learned? Well, here's my summary...

  • A pedal stroke that shows net torque to be more uniform throughout the crank revolution MIGHT be a more efficient way to pedal.
  • You can TRAIN YOUR BRAIN, adjust your fit, do other things to try and achieve this 'Roundier' pedal stroke.
  • This takes a LOT of TIME, TIME most of us DON'T HAVE.
  • If you have access to a CompuTrainer, you can 'See' whether your pedal stroke is round, or oblong, and where you apply the most pressure on each pedal stroke.
  • If you want to focus on more POWER per PEDAL stroke, then Rotor Q and QXL rings JUST MIGHT be the product for you!
  • Using SpinScan at Cycling Center Dallas, we can check pedal stroke and where this power is placed, and then confirm that with our extra cranks that have Q and QXL rings already on them. 
  • Position of a Q or QXL chainring can be altered and it can affect the location of your Average Torque Angle, and the shape of your Net Torque Curve. 
  • You can test, alter, and test again, all at CCD.

Here's our "Q" Corner at the Cycling Center Dallas location, next to Richardson Bike Mart's main location.

Rotor Cranks and Q Rings QXL rings Q Corner Cycling Center Dallas Rotor Power
Needless to say, it's not easy, it's kind of hard to understand, and it might not make a difference anyway, but as a coach for 22 years now, I really do believe that there's something "There", there, and I intend to continue testing myself and willing clients, to determine optimal location and effect. 

Special thanks to Kervin at Rotor, and yes, I am going to sell these, along with the Rotor Power Meters, to customers who value our unique attention to details like this. 


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Rodrigo Loureiro
July 26, 201510:04
Rodrigo Loureiro
Great article... I'm a big fan and user of Rotor Q-rings and have been considering 'upgrading' to QXL.Still haven't tried as I read that shifting is worse on QXL than it is on Q-rings (which by the way, works perfectly, contrary to what most people say). However, I will be putting QXL on my new bike for sure. Any comments on Q-rings vs QXL