The TorqBoard at Flywheel Revealed
Ever since I heard about FLYWHEEL, a new Indoor Cycling system in New York City I’ve been trying to learn about how their new technology called the TorqBoard worked. They apparently developed “add on” technology to an existing Red Knob bike. “Red Knob bikes” are what I call ALL the pre-power bikes of the current era – the standard type that have no gears or indicator values for resistance. This add-on was supposed to measure Power as well as RPM. Being the power partisan that I am, I just had to know how this could be. There are still only a couple stationary bikes on the market with decent power measurement, and they have had to go through years of development, and multiple bike releases to get it close. So how in the world could someone develop an “add-on” power meter for a stationary bike?
So, I flew to New York to discover it for myself – the only reasonable way to get the straight poop right? While their numbers do not really measure the metrics we understand as Power in the cycling world, they have accomplished an amazing feat – they’ve created training tools they retrofit to older Red Knob bikes! I started out quite skeptical, but ended up quite impressed. Come follow this journey.
Their little display that is attached to the side of the flywheel does indeed say “Power”, and there is a number that displays, but it is not Power in Watts as you and I (and anyone interested in real cycling power) currently understand it. It is an attempt to measure the combination of resistance applied from the red tension knob, and the estimated cadence or RPM of the flywheel, and report on that combination. First of all, yes, power in its simplest terms is a mathematical function of RPM and torque or force applied, in this case to the flywheel. So, it’s good that it is this combination they focused on. However, the question is how are they measuring these two critical components, and what is the result. Let’s break it down.
Their display spells it “Torq” for branding purposes I’m sure. This number simply reflects how much resistance you are putting on the fly wheel. I suspect they have something that is measuring the number of turns of the red knob, or somehow measuring the amount of brake put on the flywheel. As you turn the red knob, you see the power go up – even if you are not pedaling the bike. Hence, it clearly is not power. In fact, when I came into the empty cycling room early, each bike had a different power number showing on their custom display. I was ready to call the ghost busters, but instead I asked the Flywheel attendant what it meant, and he told me it was simply how much the red knob was turned or how much resistance the rider last used. While they could have called it “gear” or “resistance level”, I guess it was more chic to call it “torq”… hey, it’s NY city.
The “measured” RPM however is another story. I saw what looked like a magnet on the side of the flywheel (but I’m not sure it was), so I hoped that they were measuring this much like outdoor bikes measure RPM – with the circumference of the wheel and the number of times the magnet gets passed over. However, that may not be the case, since the numbers seemed a bit low to what my body was telling me. After having a cadence meter on my outdoor bike for 6 years, and teaching with RPM on my indoor stationary bikes for 3+ years, I am pretty in tune with my spinning speed. So I did some manual validation tests:
First, I established a steady number on their meter of 60 RPM, with a steady, smooth pedal stroke. The number held pretty consistent, never varying more than 1 RPM more or less. Once it was steady, I counted the number of revolutions (each time the knee comes up, or the foot hits the bottom of the pedal stroke can easily account for the number of pedaling revolutions), for 10 seconds (using a stop watch) and multiplying the number of revolutions by 6, giving me the RPM or Revolutions Per Minute. I also counted them for 15 seconds, and multiplied by 4 – just to vary the method a bit and see if there would be variations. While the two measurement periods (10 and 15 seconds) did not produce differences, it was difficult to get exact counts at the higher pedal rates. At 60 RPM I was a consistent 10 RPM higher in my manual test than what was showing on the meter. However, when I tested it at a steady 80 RPM those numbers seemed to produce estimates 15 to 25 RPM higher.
Consequently the cadence reported is low by a minimum of 10 RPM and a maximum of 25 RPM. This variation is likely due to this testing in a “manual” way without a mechanical device, but I can assure you, those stated RPM are definitely too low. My gut tells me that if they were validated in a controlled environment with mechanical devices, they would average about 15 RPM or more too LOW.
OK, so we have a torque number that we know is a measure of resistance, and we have an RPM reading that we know is low, but likely consistently so. The big question is where does the number under the heading of “Power” come from?
I had to slow my RPM down to as little as 60 to test the following theory, but any of you who go to FlyWheel can test this for yourself and tell me if you agree or not. As I pedaled at 60 RPM, and set my “torque” or resistance knob to a torq of 15, I saw the power number of 9 come up. So I increased my RPM to 70, and I saw power numbers jumping between 10 and 11. So I increased my torq to 20 and dropped my cadence back to 60, and I saw a power number of 12. Are you beginning to see the pattern? It is simply the multiplication of torq and RPM divided by 100: (torq X RPM) / 100. I further tested this theory by watching and pausing the Channel 7 report they so conveniently supplied on their website. Each combination of torq and rpm shown on the TorqBoard (if you pause each number combination) can be proved out by this formula, But reader beware – this is not cycling power by any stretch – it is simply a number.
This is the number that intrigued me the most. What in the world is total power? It’s sort of like asking, how many RPM did you do today. It doesn’t even make sense. But here’s the very cool part. While I did not take the time to figure out their formula on this one (I assume it adds the average power for each minute on a cumulative basis), I found this number to be completely captivating and motivating. WOW, was this a surprise! Here I am, looking down my nose at a completely false set of numbers in absolutely every category and indicator, and yet, the weirdest one of all; Total Power, was driving me on… pushing me to get to 400, then to 450 before the cool down, then I was bummed that I couldn’t hit 500 before the end of class. What just happened there!?!?
Bad Data Is Better Than No Data
At first blush, this heading may seem, well, sacrilegious… maybe even dangerous. Couldn’t bad data lead to terrible conclusions and even worse decisions? In life yes, but when it comes to Indoor Cycling the answer is maybe not.
At the end of the class, it was clear to me what Flywheel had done. They created a way to put tools on the bike, that measure your effort, hopefully in a consistent way. Forget about the purity of each measurement – the fact remains, as I’ve stated in previous blog posts; to wit – if you can measure it, you can improve it. Having some mechanism to measure how I’m doing today, I can subsequently measure how I’m doing next week, and next month, and see if I’m getting stronger, weaker, better or worse. Best of all though, in the moment, it provides some tools for the instructor and immediate feedback for the student. As weird as this sounds coming out of my own mouth… or keyboard… it’s all good!
Rock On Flywheel!
While I won’t even comment on the custom weight holders attached to each bike, and my disdain for contraindicated movements and activities on the bike, I must commend Flywheel for bringing tools into the Indoor Cycling environment – and doing it by retrofitting older bikes. If you can get by all the numbers being mislabeled, inaccurate and in some cases just silly, you may just find yourself working harder than you thought possible, just to get to that next level. Well done Flywheel, keep on flying!