Power meters have revolutionized the way cyclists train and race. Every professional team uses them as their primary training tool, and more and more citizen racers and weekend warriors are making the investment every day and reaping the rewards.
The goal of any cyclist is to ride faster for a longer period of time. And as technology has changed, riders have evolved as well, and have used a variety of methods to train.
Cyclists initially trained and raced using “perceived exertion” only. Long aerobic rides would be at an “easy” pace and intervals would be at a “hard” pace. And depending on how they felt any given day, this “easy” or “hard” pace could be very different.
The next generation was heart rate monitors. This was a huge revolution and most cyclists have used HRM’s and still use them as their fundamental training tool. Heart rate monitors were a quantum leap in the ability to monitor training and effort levels, are easy to use and inexpensive. These offer a great alternative to training based on perceived exertion only.
The downside with HR monitors is that they are really an “indirect” measure of effort. Heart rate can be affected by a variety of factors, including fatigue, stress, dehydration and sleep, among many others. So a given effort may produce different heart rates on different days. So while heart rate training is good, it can include a significant amount of error. A power meter, on the other hand, eliminates much of this.
First of all, what exactly is a power meter? In the broadest sense, it’s simply a device that tells the rider how much power he or she is putting to the pedals. There are nuances between brands about how and where the power is measured, but the information they provide is similar – the number of watts produced as the rider turns the pedals.
A power meter is a DIRECT measurement of effort, and the results are available to the rider immediately. While heart rate typically lags effort (which makes riding short intervals with a heart rate monitor difficult to control), a power meter provides immediate feedback as to the effort.
So when a rider using a HRM rides an interval, effort will often be much too hard at the beginning, then they “crash and burn” toward the end as the effort can’t be maintained. A cyclist using a power meter will be able to dial in the exact amount of effort during the interval necessary to produce the desired effects.
Power meters are fantastic tools for time trials and for triathletes. The rider knows exactly the amount of power they can produce for a given time period, so they can ride that to a great time or placement. And power meters are great for the weekend warrior riding a century or any fast club ride as well.
The biggest difference between HRM and power meter training is this: While heart rate, the heart rate may stay the same over a period of time, but the power output will fall. For example, a cyclist performs a 30 minute TT and determines threshold HR to be 170. While they are able to maintain that level of heart rate, the power they produce over that 30 minutes falls during the course of the TT, and this power drop is usually significant.
And remember that the bottom line to a cyclist is the amount of power they can produce. So if HR remains high yet power (and speed) decays, they haven’t gotten what they wanted, which is to ride faster, longer.
When using a power meter, however, power applied to the pedals can remain constant over the given time period. So when setting training zones based on power, the rider goes as hard as they can for the 30 minutes, adjusting power constantly to remain on the “razor’s edge” of riding as hard as possible without blowing up.
The plot of the heart rate curve in this case will start out lower and will gradually rise, then will eventually level off. The plot of the power output will be nearly flat.
So while one graph shows a steady heart rate and a reduction in power over time (heart rate-based), the other will show a steady power output and a rising, then leveling off heart rate (power-based).
Bottom line? Power meters offer huge advantages to the serious cyclist. The downside is that they are expensive, but ride once using a power meter and you’ll never go back to training only with a heart rate monitor.
I personally ride with a Saris Power Tap and have for several years. I’ve been more than pleased with the technology, with the ease of use and with Saris’ customer service. I’d be happy to share my personal insights if you’re interested.
I’ve had many people express an interest in seeing my workouts, so I’ll include them here. Yesterday I did the following:
- 30 minute recovery spin in the morning
- Afternoon ride included intervals at VO2 Max power levels:
- 4 min on, 4 min recovery interval (RI)
- 3 on, 4 off
- 2 on, 4 off
- 2 on, 4 off
- 3 on, 4 off
- 4 on, 4 off
- then 6 x 1 minutes on, each with 2 minute RI
Please contact me with any questions you have about power meters and how they can benefit you. Add your comments below, then GET OUT AND RIDE!
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