Why You Need a Power Meter

Should you buy a power meter? After all, they aren’t cheap and sport is already expensive. You’ve spent a small fortune on bicycles and all of their assorted and costly components. And don’t forget the entry fees, travel to races, special foods and supplements, and on, and on, and on.

And why get a power meter since you already have a perfectly good heart rate monitor? It’s just one more gizmo to have to figure out.

So why should you get a power meter? The short answer is that you simply are more likely to achieve your race goals by training—and racing—with a power meter than without. It is the most affective tool you can get to go faster on a bike.

Here’s Why

Don’t get me wrong, heart rate monitors are great intensity-measuring devices, also. But heart rate by itself actually doesn’t tell you much. It’s like the tachometer on a car—it tells you how hard the engine is working. Nothing more.

For example, what if your heart rate is 10 beats higher than usual? What does that mean? Is it good or bad? The only way to answer that question is to know if you were putting out more power or less than usual.

Input data such as heart rate isn’t meaningful until it is compared with some measure of output. Output is critical to success; input isn’t. After all, they don’t give awards at races to those who worked the hardest or had the highest heart rates (input), but rather to those who had the fastest time which results from high power (output).

Let’s get back to why you should get a power meter.

No More Guessing

Should you buy a power meter or fast wheels? Given the choice I’d recommend a power meter every time. When it comes to speed the engine is always the most important part. A power meter will help you develop a bigger one. With sleek wheels you still have a small engine.

How do they make your engine bigger? Power meters remove most of the guesswork that goes into training and racing. For example, I’ve known athletes who when doing intervals with heart rate monitors don’t call the work interval “started” until their heart rates reach the targeted level which could take several minutes. During that time they are guessing how hard to work. With a power meter you soon learn that the interval starts as soon as the power hits the targeted zone—which means right away. You get the intensity correct immediately with no guesswork. The intervals don’t taper off near the ends any more either. This means no wasted training time and precise intensity.

Also, realize that you’re not trying to train the heart solely when doing intervals or any workout, for that matter. In fact, what happens in the muscles during workouts, not the heart, is really the key to your success. Heart rate monitors, while quite valuable to training, have many believing that training is just about the heart. It isn’t. Power meters allow you to focus more on muscle.

Cheating With Power

Using a power meter in a long steady-state race such as a triathlon or long time trial is almost like cheating. When everyone else is fighting a head wind, excitedly going too fast down wind or guessing how hard to push when going up hill, the athlete with a power meter is just rolling along at the prescribed power. He or she will produce the fastest possible ride given the conditions so long as the optimal target power has been determined through training and observed closely during the race. While something similar can be done with heart rate there are some confounding factors such as the excitement of a race, cardiac drift, the acute effect of diet and the slow response of pulse on hills, accelerating out of corners or when passing others.

Power meters also provide highly accurate details about how your fitness is changing throughout the season. I test the athletes I coach regularly using a combination of heart rate and power. Without this information I really wouldn’t know for sure if they are making progress. I’d just be guessing. Now I can precisely compare output with input by dividing the average (or, preferably, “normalized”) power for a workout by the average heart rate. An increasing value for similar workouts tells me fitness is improving.

Moving On Up

There are many benefits of training with power. But perhaps the best indicator of their value for performance is the elite athletes who use them. Power meters are common with pro road cyclists and they are becoming increasingly popular with pro triathletes. Cyclists are increasingly using them. Age group triathletes have been slow to adopt this technology, which is unusual. Over the past twenty years triathletes were the first to adopt such innovations as aero bars, beam bikes, deep-dish rims, clipless pedals and gels.

The trend is definitely toward the adoption of power meters in road racing, triathlon and mountain biking. Many are leaning that a power meter will help them race faster. Start setting aside a few bucks aweek so that some day you can get one. It will definitely change how well you train and race.

Comments

[Bryan]

http://sites.garmin.com/vector/#power is the new Garmin setup. Thinking pretty seriously about buying these.

[rumpole]

As a not very good cyclist, I will say this:

1. Learning to use the PM is easy. Run test. Do 20 min intervals @ 90-100 percent FTP. Watch FTP rise. It's that simple. No guesswork-the body responds to stimulus. (Given the limited amount of workout time I have during the winter, I focus on higher intensities than the classic periodization plans.).

2. Learning to interpret the data is a whole 'nother kettle of fish. I've been at it a year, and I now understand how to use it a lot better, and feel like the gains are more consistent. Joe's books combined with the Allen/Coggan book are pretty much all you need. The analysis is a big part of this. If you don't enjoy this part of the tool, the PM is still useful, but it's more fun if you like to use the charts in figuring out strengths, weaknesses, etc. If you do enjoy it, it adds a whole new aspect to the hobby.

3. It is harder to dial in intensities outside than inside. Learning to pace that way in a specific range outside (rather than hammer, pant, recover, hammer) is helpful in learning your limits and pacing, and becoming smoother in delivering power to the pedals.

Could you learn to do this with RPE and HR? More or less, yes-once you dialed in what FTP "felt" like vs what tempo vs VO2, etc., you'd probably find yourself getting it more or less right. But I have no desire to go back.

[Roygalvin]

I noticed that in trainingpeaks. I upload daily including my commutes, though my TSS & IF seem way off (underestimated) but again it is only as accurate as the numbers that I have set for my HR. The thing is for whatever reason (and there maybe many) I get totally different numbers for an indoor threshold test v outdoor test. My FTP is a lot higher outdoor than indoors. Here where the problem is, the numbers that I've set at the moment in trainingpeaks & WKO both watts & hr are based indoors, why because that's where I do all my intervals at the moment & may get out for one or two 4hrs+ group rides at the weekend, because of this my eTSS & IF taken from Edge outdoors are way out. A suggestion maybe to have 'two' sets of ftp & hr values, one for 'outdoor' and one for 'indoor'. When uploading to trainingpeaks have a check mark to indicate if it was an outdoor or indoor ride. Maybe this could be linked into device agent? Just a thought.

[CS]

So it seems a power meter isn't just a technical training tool but can act almost as a motivational device as well, by knowing your current power level and trying to beat it?

Since a power meter makes tracking progress/improvement easier, it seems it would make training more regimented and productive, since there are specific levels to work against. Definitely a cool product I'll have to check out.

[Faizel]

I received my PM, 3 months ago, as a competitive age group roadie, it is the best investment I have made in my training arsenal.
Last week I was doing a crit and could not hold onto the younger more elite riders in the bunch due to some heavy crosswinds. Instead of beating myself up for not being able to hold on, I realsied that my power output was quite high. I continued to focus on pushing my power for the remainder of the 60 min. As a result I improved on my previous CP60. So my session turned into a motivator due to the presence of my PM.

[Ted Inoue]

Hey Joe,

First - thanks for the years of guidance you've provided. Your scientific approach to training has helped me and teammates reach new fitness levels since the 90's.

Last fall, I rediscovered power meters after a decade hiatus of "just going out and training." As a 47 Y.O. masters racer, I need all the motivation and focus I can get when training - I just wasn't able to go out and suffer like I could in my 20's.

A power meter, combined with the Strava service has taken me back to fitness levels I haven't seen in a long time! I can now compare my own performance and that of others on various training segments so I get to quantitatively evaluate my training in a way just not possible with a HR monitor or timer alone. It's actually making intervals fun again.

So there's the quantitative aspect of power meters that's motivating as well as the social training that is now possible. Combined, I feel like we've entered a new era of training and expect to see a noticeably higher level of competition on the race circuits.

[Doug Perry]

Garmin's Vector powermeter is scheduled to be available in March, 2012. I believe it will be worth waiting for .... hub based meters, like cycleops, ties you to the wheel. Crank based systems, like SRM, tie you to the bike. With the pedal based Vector, you can switch bikes and wheels ... put on the pedals and your good to go!! It will cost you in between the cost of the hub and crank system ... $1,499.99.

[Mikołaj Mucha]

Hello Mr. Joe Friel and everyone,

I have a question regarding section "cheating with power". It says that the optimal target power should be determined through training. I have tried to do the research on that, but I'm afraid I don't know how to determine the target power?
Moreover, is it possible to determine a kind of "target heart rate" using HR monitor? I know that hr monitor can be very misleading in the race, but can it be of any help?
So far, I've got to know that one can last up to an hour at the lactate threshold but what about longer events such as 2-3 hours MTB race or a marathon or an ironman?
I understand that there is no easy answer to that, but can You shed some light on that or suggest some reading?

Last but not least, because it's my first time writting here, I would like to thank Joe Friel for all of His work, especially for coming to Poland, I hope You liked the sightseeing and the museum :)

[dindu]

joe, thanks for the insightful article! i used to have a quarq but didn't know how to use it well, so i've sold it.

now, you blew me away with the Avg Normalized Power / Avg HR so much that i'm back in the market for another quarq!

this ratio is what i've been sorely missing my first time around with a PM! what is this metric called?

[dindu]

"Now I can precisely compare output with input by dividing the average (or, preferably, “normalized”) power for a workout by the average heart rate. An increasing value for similar workouts tells me fitness is improving."

What's this metric called ?

[dindu]

great article, joe!

"Now I can precisely compare output with input by dividing the average (or, preferably, “normalized”) power for a workout by the average heart rate. An increasing value for similar workouts tells me fitness is improving."

that's what i've been looking for! does this articular metric have a name?