Powermeters

"What is a power meter and how can it help me?"

This question is asked on a regular basis by people looking for anything that can help make their training more efficient. Anyone who has a speedometer on their bike can tell you that wind and hills make speed a useless measure of training intensity. Heart rate, on the other hand, is a great way to measure training intensity and has been extensively used since the first heart rate monitor came out in the 1980's. There is a mostly linear relationship between heart rate and exercise intensity, and we can show this nicely in the chart below. In other words, as your heart rate increases toward your maximum, so does exercise intensity. The same cannot be said of the relationship between intensity and speed, for example.

From a practical standpoint, heart rate is limited in its usefulness in some circumstances. For example, dehydration and overheating can increase your heart rate well beyond what it would normally be, making it difficult to know how hard to exercise. It is often very clear to the person exercising that they might have to ride more slowly for the same heart rate when it's hot outside (or inside), but does that mean you are still training at the right intensity? I don't think so.

Quick changes in intensity such as a surge up a hill or even interval training are not obvious when only looking at heart rate. In these situations, heart rate lags behind the effort. With the exception of laboratory testing and perhaps well-controlled indoor training sessions, effort is never constant, so using a tool that is 20 or 30 seconds behind what is actually happening can make interpreting training data difficult. This is especially the case when looking at your average heart rate for a workout, because the time spent 'catching up' to the intensity means that average heart rates are often lower than the target or the expected heart rate.

Another problem with using heart rate by itself to judge exercise intensity or training load is that exercise intensity can increase way above the level we would associate with maximum heart rate. Think about the 100m dash! That is obviously an all-out effort, and yet not one of those athletes will reach maximum heart rate, or if they do, they could run quite a bit slower, and still get to max heart rate. In other words, heart rate is great for showing how hard you're working on long, steady efforts where there aren't any major environmental factors or speed changes/hills, but wouldn't it be great if we had something that could tell overcome some of these challenges? Enter the power meter.

Cyclists and Triathletes enjoy unparalleled access to training information now that power meters have become more accessible. The most widely-used systems involve replacing a standard crank or rear hub with an instrumented unit. These systems convert measurements of torque, combined with how quickly the crank or wheel is rotating, to figure out power output. This torque comes from your legs, and is what we're all interested in. Power is intensity. Unlike heart rate, these power meters instantly know (and tell you!) when there is a surge and whether you're riding into the wind or up a hill, watts (the measurement unit for power) are still just as good a measure of intensity as they are at any other time. Watts are not affected by your environment, either, even if you are. The adage, "watts are watts are watts," is often cited at this point. No more will you give yourself a hard time if you don't hit an arbitrary average speed for a ride, you can get off the bike comfortable with the knowledge that your ride was exactly as hard as it was supposed to be, confident you are maximizing your training time.

A key point to make here is that having heart rate along with power is superior to either one in isolation. Although I have suggested that heart rate monitors are not as useful because they are affected by things like dehydration, they become extremely useful when combined with a power meter for the same reason! If your heart rate is inexplicably high relative to a power output you normally train at, it could be an early warning sign that you need more rest in your training plan. Looking at it another way, the easiest way to see that your training is working and you're getting fitter is to see consistently lower heart rates for a given power output. Also, there is some fantastic software than can help you look at your power data such as TrainingPeaks' WKO+ or Race Day Performance Predictor. This software helps tease out the relevant information from each training session so that you can get beyond just looking at average watts.

We at TCR currently offer the Quarq Cinqo (crank-based) as well as the CycleOps PowerTap (hub-based). The Quarq certainly has the edge in my book, because you can train AND race with power. Often with the PowerTap, you need to have one set of wheels with the power hub installed and another set for racing, for example. That's if you choose to put the power tap in your training wheels, but training occupies much more of your time than racing, so I would certainly recommend going this route if you like the PowerTap. From a cost standpoint, both the PowerTap and the Quarq have the other major player in power meters, the SRM. While none of the systems are cheap, you can get one of the two systems we offer for close to $1000 cheaper. We are also eagerly awaiting the release of MetriGear's Vector, a pedal-based power meter, for its ease of use, its cost, and the fact that it won't have to be exclusive to one wheel, bike, or even drive-train! With all the bike fitting we do here, the ability to separate out left and right leg power would be very useful for many people to improve their cycling efficiency as well.

The new wireless technology standard (ANT+, developed right outside Calgary, by the way) means there is a lot of interoperability between power meter manufacturers and makers of bike computers. In my opinion, the CycleOps Joule 2.0 is the best power bike computer available from a training standpoint, but Garmin (maker of the Edge 500 and Edge 705 computers) offers some excellent GPS functionality as well. If you already have a power meter, we are also excited to offer to help analyze the myriad of data that you have at your fingertips. Sometimes an experienced observer can pick out some relevant information you might have missed or can help you identify your individual strengths and weaknesses to help you get to the next level. Power meters really are the ultimate training tool. Other sports yearn to have such an in-depth understanding of the training they do. Power meters are coming down in price, and the new ANT+ wireless standard means easier installation and maintenance of the equipment. It's an exciting time to be involved with cycling, to say the least!