This is perhaps one of the most frequently asked questions. While we don’t give concrete buying advice and don’t want to look into anyone’s wallet, there are a few things to look out for. If you take these tips into account in your search, the choice will probably be made a lot quicker.
WHAT DOES A POWER METER MEASURE?
A power meter is little more than a (strain) strip that measures how much it is deformed when force is applied to it. In doing so, a power meter must also know what the pedaling frequency (rpm) is, because force times speed ultimately produces power. With the right calibration and thus the measurement of this deformation and cadence, a number is sent to the bike computer and you know what the delivered power is. This principle is the same for every power meter, but can be applied in different places on the bike.
Power can be measured on the bottom bracket or spider (SRM, Quark, Rotor, Power2Max), cranks (Shimano, Stages, 4iiii) pedals (Garmin, Favero, Powertap) or in the rear wheel (Powertap). There are also some other exotic solutions on the market, but that doesn’t get much better in terms of reliability and repeatability (more on this later). A rear wheel or pedals are super easy to mount, but then you are stuck with that one wheel or a specific pedal system. A spider system or crankset requires a bit more assembly work, often you have to replace the whole crankset, but then you don’t have this problem.
Another thing to consider is how reliable the power meter is. Does the power meter measure what you want to measure. If you pedal 200 Watts, does the power meter indicate 200 Watts. There are many blogs about this and power meters are compared with each other. This seems super important, but actually it’s not. A power meter is mainly a tool to improve yourself and to compare your power values with your own previous power values. If your power meter is always 20 Watts off, it does not matter much at all. You then only have to be careful not to compare your power with someone else. In this light, a single-sided power meter is actually fine for every recreational cyclist. A single-sided power meter is only mounted on the non-drive side and multiplies this power by two. This factor can often be adjusted with the bike computer. Nobody always pedals exactly with 50% of the total power with the left leg. As long as you always compare your own values with the same power meter, this doesn’t matter all that much.
The fact that a power meter indicates 200 watts one day and 220 watts the next is a much bigger problem. This is about the repeatability of the measurements. Often when the battery voltage gets too low, for example, every power meter suffers from this. In a general sense, you see that new power meters that have just come on the market have problems in this area. It often takes a few generations before all the small problems are solved.
Buy a power meter that is easy to mount on the bike without too many modifications. If you already have a Shimano crankset, ask yourself if you want to replace it with a Sram or Rotor system. In addition, choose a power meter that has been on the market for a while and which has no teething problems anymore. If a single-sided power system fits your current crankset and if you mainly want to compare the power with yourself, go for a single-sided system. If you insist on a power meter that you can easily switch between, say, your time trial bike and road bike, consider a pedal system or rear wheel.
If need any more help, feel free to contact us. Or take a look at our other services and our training plan app JOIN cycling.