Power Meters, a crash course in terminology
Power meters are the latest gadget in a cyclists armory and many riders are using power data to gain some insight into their own riding capacity and improve the efficiency of their training. Many riders have power meters without really understanding the full suite of information provided by their new riding companion. So here is a basic guide to some of the new power language that currently dominates the chatter in riding bunches all around the world:
Normalised Power. This is the power output of the rider AFTER the numbers have been "smoothed out" and most of the junk data (really high and really low numbers) has been taken out. Strava uses "average weighted power" to show the same information. A true reflection of your ride's average power.
Power Balance. The relative contribution of each leg to the overall power output. Ideal is of course 50/50 but anything from 47-53 to 53/47 is considered normal and most cycling trainers do not work hard to correct balance unless it is outside of this range.
Watts / KG. This one is often considered the "holy grail" of power assessment, particularly when looking at climbing capacity. It is the riders power output divided by body weight in KGs (some trainers divide by the combined weight of rider + bike). Usually this is measured when a rider is at threshold and pros will have a number somewhere around 6 - 6.5, NRS racers around 5.5 - 6 and so on down the line.
Pedalling Smoothness. This is a fairly new addition to most power meters and the significance of the data to riding performance is really yet to be tested. Pedal smoothness shows how evenly you generate power on each leg. A high % (30 - 40) means that your average power production is high compared to your peak power production, or in other words, you "spread your power out" rather than dosing it in a concentrated part of the pedal stroke. You will never see 100% and are not meant to, Garmin says that 40% is about as high as they ever saw in testing. It is worth noting that the PS % will be higher when climbing for most and riding flat roads with higher cadences will usually show lower %s.
Torque Efficiency. Another of the new data sets available on most power meters (usually requires a firmware update unless your PM is pretty new) and shows how much a poor or lazy upstroke (or poor cycling motor pattern) is negatively effecting the downstroke. Almost all cyclists exert some downward force on the pedal when it is moving upwards (the upstroke when we are meant to be "pulling up") and this of course works against the down force being produced by the opposite leg. A higher % in TE means that the negative impact of the non-drive leg is being minimised and a lower % of course means that a lazy upstroke is detracting from the work that your drive leg is doing. TEs of between 70-90% show a high level of down / upstroke efficiency and if the numbers are much lower than this, some time in the program should be devoted to technique improvement.
Hopefully that has helped in some small way.
Stay safe out there
Train Smart & Race Hard
Brian Bubba Cooke
Exercise Physiologist, coach & cycling tragic for 30 years. Love the freedom, reward and sense of achievement that one can only experience in our amazing sport.