What Does it Mean to “Train with Power?”

This blog brought to you by former TriSports Champion Mike VanHouten. Power is definitely a buzzword in triathlon right now, but what does it all mean? Mike will explain it very simply so you can decide if power is right for you.

No matter if you have just started doing triathlons or if you have been doing them for a while, you have heard of people talking about training with power on their bike. So what does that really mean?

Very simply, a power meter measures the amount of effort you are exerting on your bike in watts. Two of the most common types of devices that you can buy today are a wheel hub or crank-based power meter. A hub-based power meter allows you to replace the existing hub on your rear wheel and replace it with the new hub that has a power meter inside of it. A crank based power meter simply replaces your existing crank and has the power meter inside your crank arms. (editor’s note: Garmin and now Powertap have introduced pedal-based power meters, allowing for increased portability between bikes.)

Crank and Hub-based Power Meters

So which one is the best?

There’s no right or wrong answer, it really depends on what makes sense for you. One advantage of a hub-based meter is cost, they typically can be a few hundred dollars less expensive than a crank-based power meter, and another advantage is you can use that same rear wheel power meter on all of your bikes. A disadvantage is the hub can only be used for the wheel it is installed with, so if you have multiple wheels for training vs. racing, you would need to decide which wheel would have the hub power meter. For a crank-based meter, the wheels are independent of the power meter, so you can use whatever wheel you want, but if you have multiple bikes, you would have to swap out the crank from bike to bike (assuming your bikes can utilize similar cranks). While this isn’t hard to do, you may need some special tools, or you can utilize your local bike shop to quickly do the job for you.

One additional piece of equipment you will need is a bike computer or exercise watch to read the data that the power meter sends out while you are riding your bike. The good news is that you may already have a device that is compatible, just check to see if your device is “ANT+ power meter compatible.” Using your home computer, you can retrieve and review this data to see your power readings along with other information like your pedaling cadence, speed, and elevation changes.

ANT+ Enabled bike computer

So now that you know the basics of what a power meter is, the obvious question is… what can it do for you?

First a power meter allows you to maximize your training time and effort. Your training time is valuable, and it is important to know how hard to push and when to back off for recovery. Instead of basing your bike workouts on your perceived effort or your heart rate (which can vary day-to-day), a power meter gives you precise information on how hard you are working and how that compares to your maximum effort. This maximum effort is called your Functional Threshold Power (FTP), which is, simply put, the average watts you can exert over an hour with nothing left in the tank afterwards.

How do you figure out your FTP?

I like to utilize a 2×20 minute workout with 2 minutes of active rest (don’t stop pedaling) in between. Your goal in this workout is to be as consistent as possible and to be completely exhausted when you are done. After your ride is complete, you want to look at the average watts that you utilized over the 42 minutes. For example, if your average over the 42 minutes is 200 watts, this is now your FTP.

Now that you know your FTP, your workouts can be structured and precise. When your coach or training plan tells you to do a recovery ride for an hour at 60% of your FTP and your FTP is 200 watts, you simply target an average effort of 120 watts. The guessing game of knowing if you are riding too hard or not hard enough is gone.

The second thing you will gain by utilizing power on your bike is that you can now target a specific effort for your race. In a sprint race, you may ride your bike leg with an effort at 100% of your FTP, but for an full distance race you may want to target an effort of 70%. Why is this important? This will allow you to maximize your effort on the running leg of your triathlon by not going too hard on your bike leg, something that is commonly done in races.

I’ve tried to keep this description fairly simple, but if you’re interested in learning about getting a power meter, give TriSports.com a call to get advice on your existing equipment and what options are available to you. There are also great books available that can really explain the details of training with power, or if you have a coach, talk to them and understand how your training and races could benefit by utilizing this technology.