Advanced technology means
Simplicity and Portability
- PRODUCT REVIEWS
- COMPETITIVE COMPARISONS
- POWER METER BASICS
- OPPOSING AND APPLIED FORCES
- HOW WE CALCULATE POWER
- HOW OTHER PRODUCTS CALCULATE POWER
If you’re skeptical that PowerPod and Newton have accuracy comparable to other products, you are not alone! Here is a review of Velocomp power technology published in road.cc The reviewer freely admits he was very skeptical, but after 3 months of testing he concluded his Velocomp power meter (Newton) was within 2.5% of his direct force power meter. The overall verdict? ” [An] Innovative power meter that offers results comparable to others, along with features to improve your position and technique.”
Another review (from a PhD cycling coach!) says Velocomp technology seems magical. Well, we’re not magicians; we are physicists, engineers and cyclists, focused on one thing: making our power meter products better and better.
If you’d like to read what real customers have to say about PowerPod and Newton, check out the testimonials sprinkled throughout the website.
For more independent reviews of Velocomp power meter products, from publications around the world, check out the Rennrad (Germany) review here , the Bicycle Australia magazine review here , Florida Cycling Magazine review here , the Bicycling.net review here , and the Cycling Power Labs review here.
We’ve been comparing our power data with other power meters for 12 years (longer than most of our competitors have been in business).
Linked below is second-by-second ride file data, complied by cyclists around the world. Judge for yourself!
NOTE: All Velocomp products use the same digital sensors and same patented power measurement methods, so every comparison in this section applies both to PowerPod and Newton!
POWER METER BASICS
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
So, power meters measure both force AND speed during every moment of a bike ride.
The primary technical challenge power meters face is force measurement.
OPPOSING AND APPLIED FORCES
Cyclists pedal against the opposing forces of Nature: wind, hills, acceleration, and friction.
FORCES OPPOSING FORWARD MOTION
According to Newton’s Third Law, “Opposing Forces equal Applied Forces“.
So, the opposing force caused by wind, hill slope, acceleration and friction is EXACTLY THE SAME as the applied pedal force.
HOW VELOCOMP CALCULATES
Accurate, Proven, Solid-State Sensors
Digital accelerometer and dynamic pressure sensors, the kind used in aerospace applications, are mounted inside Velocomp power meters. These sensors measure forward acceleration and opposing air pressure. Because the sensors experience very little stress they require no maintenance or periodic recalibration.
A wireless sensor mounted on the chain stay measures bike speed.
Aerodynamic and Frictional Drag Coefficients
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.
Velocomp “Physics Engine” Converts Sensor data into Power
On the road, Velocomp’s “Physics Engine” converts air pressure, accelerometer and speed measurements into opposing wind, hill slope, acceleration, frictional forces.
The total opposing force, multiplied by bike speed, equals cyclist power.
Because they accurately measure opposing forces and speed, Velocomp power meters accurately measure power.
HOW OTHER PRODUCTS
When cyclists apply power, bike components (hub/chain/bottom bracket/crank/pedals) flex in response.
Traditional, “direct force power meters” use strain gauges, mounted in the pedals/crank/hub, to measure bike component flexing. Note that strain measurements are NOT power measurements; complex algorithms convert strain and cadence data into cycling data.
Electronics located inside the hub/crank/pedals convert strain gauge measurements into applied torque (rotational force) measurements, averaged over the entire period of rotation. Measuring applied forces over the full turn of the crank (“both leg DFPM”) is a very solid technical approach that has been proven over the years.
A lower cost, but accuracy-compromised approach measures strain/torquein one leg only (“one-leg DFPM”), then multiplies the result by 2.0, using the assumption that both legs apply power identically. Since this approach measures cyclist torque only on one leg, the actual power accuracy over the full pedal stroke is unknowable.
Torque measurements are multiplied by cadence (rotational speed) to calculate power.
Because power meter hubs/cranks/pedals experience the full, concentrated torque of the cyclist, for extended periods of time, they periodically require factory recalibration/refreshing.