What’s a power meter?
A power meter is a device that is placed somewhere between your legs and the rear tyre of your bike and it gives you a measurement of the power being produced by the rider.
This measurement is expressed in watts and is often expressed as a percentage of the weight of the rider, so for example an 80kg rider making 300 watts would have a 3.75 watts/kg. Putting the power into a Watts/kg takes into account the weight of the rider rather than just the power produced.
Why use power?
Using power as a measurement is useful as It removes variables for instance strong winds or hills will slow an average speed for a ride but will have a minimal effect on the power number you make.
Power is an almost instant measurement unlike heart rate and so for short efforts, it is easy to set a target as opposed to a heart rate value that will take time to come up to a target. It’s because of this that wherever you find professional cyclists or triathletes, power meters won’t be far away.
Power vs heart rate
While there are some very huge benefits to using power, there is a reason you still see professional cyclists and triathletes using heart rate for training and racing. While it’s not hard to see the benefits it also has some limitations not limited to the fact that you are looking at the output with the power meter where the heart rate monitor gives you a glimpse into how hard the body is working. When all things are equal you can conclude the power being made by an athlete and the workload this is exerting on the body but as we all know things are never that simple and any number of variables can reduce the body’s ability to do work, things like heat, stress, dehydration just to name a few.
There are three main types of power meters
- The crank-based meter generally measures output from both legs (or single-leg options are also available) and replaces your regular crankset as such is something that an experienced mechanic will need to do and can be a bit complicated getting the right fitment for your bike.
- A pedal-based meter and as it sounds this replaces the standard pedal on your bike, these can be either a single or dual leg. I would say these are things you can fit yourself.
- Crank arm meters replace just one arm of the crank and these are single-leg only. Like the pedal-based meter when used as a single leg the device simply doubles the value that it measures from your one leg.
