“Any sufficiently advanced technology is indistinguishable from magic”
That’s how one reviewer began his detailed review of Velocomp’s patented, opposing force power measurement approach.
Read the full review.
How PowerPod works isn’t magic, but what it does is the result of ingenious science and engineering.
If you are skeptical about PowerPod’s accuracy compared to other products, you are not alone. Let us explain how PowerPod works. Power, measured in watts, is the work you do each instant of your bike ride. Physics measures power by this formula: Power = Force x Speed. Power meters measure both force AND speed during every moment of a bike ride. The primary technical challenge power meters face is the force measurement.
PowerPod takes into account opposing forces, including wind, hills, acceleration and friction. According to Newton’s Third Law, “Opposing forces equal applied forces“. So, the total opposing force caused by wind, hill slope, acceleration and friction is EXACTLY THE SAME as the applied pedal force.
Digital accelerometer, dynamic pressure, and barometric pressure sensors are mounted inside PowerPod. Unlike applied-force power meters, PowerPod sensors experience nearly zero stress, so they don’t wear-out and do not require maintenance and factory recalibration. A wireless sensor mounted on the chain stay measures bike speed.
As part of initial setup the user enters total bike/rider weight, tire size and road surface, rider height, and ride position. From these inputs the rider’s CdA (coefficient of drag), and bike Crr (coefficient of rolling resistance) are determined. PowerPod’s “Physics Engine” converts air pressure, accelerometer and speed sensor data into wind, hill slope, acceleration and frictional forces. The total of these opposing forces, multiplied by bike speed, equals cyclist power.
As you turn the crank, your left and right legs accelerate (power) the bike. PowerPod measures bike acceleration 800 times per second, capturing the effort of both legs, and delivering both-leg, +/- 2% accuracy.
PowerPod vs. Direct Force Power Meters (DFPM)
When cyclists apply power, bike components (hub/chain/bottom bracket/crank/pedals) flex in response. Traditional DFPMs use strain gauges, mounted in the pedals/crank/hub, to measure bike component mechanical flexing. Note that strain gauge measurements are NOT power measurements. In fact, electronics and complex algorithms located inside the hub/crank/pedals convert strain-gauge-flex voltage into applied torque (rotational force) measurements. When torque is multiplied by cadence (rotational speed) a power number is calculated.
High-quality, both-leg DFPMs measure, moment-by-moment, the forces produced by BOTH legs. Using many strain gauges, both-leg DFPMs measure forces during the entire turn of the bike crank. Measuring the forces of both legs, over the full turn of the crank, is a very solid technical approach that has been proven over the years. But both-leg power meters are expensive; expect to pay around $1000 or more.
Less accurate, lower cost, one-leg DFPMs measure the strain/torque of one leg only. By using fewer strain gauges, and measuring the forces of one leg only, the manufacturing cost of the one-leg DFPM is less. But how does a one-leg power meter measure the TOTAL power of BOTH legs? The truth is, IT DOESN’T; a one-leg power meter multiplies its one-leg measurement by 2.0, making the assumption that both of your legs apply power identically. No cyclist has a perfect 50-50 split between left and right legs, and the real-life split can’t be measured with a one-leg power meter. So no matter what their marketing brochures say, the actual accuracy of a one-leg power meter on YOUR bike is unknown.
Finally, all DFPMs are electromechanical devices that experience the full, concentrated energy of the cyclist, every ride, every turn of the crank, every year. Consequently, DFPMs periodically require factory recalibration/refreshing.
PowerPod measures the power produced by both legs, without mechanically stressing any PowerPod sensor. It’s maximum accuracy with minimum stress.
PowerStroke Cycling Measurement
PowerStroke pedaling efficiency and economy reveals not only how much power you produce, but how well you produce power as you turn the crank. PowerStroke shows wasted watts, wasted motion, and wasted energy in left/right, front/back, and side/side views. You also get a view of your pedaling smoothness as you turn the crank!
Use PowerStroke insights to adjust your bike fitting, your pedaling style, even your saddle! Test how aerodynamic you and your equipment are. Try different ride positions, helmets, wheels. PowerStroke guides you to an optimum, economical left/right pedal stroke.
Isaac software for Mac/PC, downloadable below, helps you get the most out of your training. Isaac gives you detailed information and insights about your ride–information that no other power meter can provide.
Isaac software also lets you update your PowerPod firmware–the computer program that runs your power meter electronics. Isaac software and PowerPod firmware updates are FREE.
Click to Download ISAAC software:
PowerHouse is Velocomp’s free bike app that delivers pro-level, personalized power-training plans and workouts to help achieve your fitness, weight loss, lifestyle and performance goals.
The plans and workouts were developed by cycling coach Hunter Allen, the guru of training with power meters. Audio and video feedback from Hunter is there to keep you motivated.
Click to Download app:
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