Garmin screen during Zone 2 base training

When is your Base Training done?

Building Base Fitness used to be done only by feel. Not anymore.

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  • Base Fitness is really aerobic fitness
  • When your heart rate is “running even” with your power, you’re done
  • Heart rate only? When your speed is faster for your Zone 2 days, you’re done
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“Ride lots.”


Those famous words uttered by the most famous cyclist ever, Eddy Merckx, were in response to an interviewer’s question about The Cannibal’s training protocol.

In many ways, that response was the response of a previous generation of old-school racers. Cycling, being steeped in tradition, and no small amount of superstition, has managed to hold on to that phrase with a grip worthy of going over washboard pavement.

The idea of arbitrary “monster miles,” or “base miles,” doesn’t really get to the heart of the matter, if you will pardon the pun. What you’re trying to do, when laying down a foundation for base training, is really training your heart and lungs.

If you have both a power meter and a heart rate monitor, the process is rather straightforward.

For a period of 6 to 12 weeks, and obviously your mileage may vary (sorry, more puns again) you’ll want to run steady in your Zone Two heart rate. Ignore power.

If you are using WKO+ software from Training Peaks, or, if you use a Mac computer, as I do, with Golden Cheetah, you will simply want to observe your Efficiency Factor over that 6 to 12 week period. If you don’t see “efficiency factor,” poke around in the various menus until you can turn that feature on. In GoldenCheetah, you can find it in the column chooser.
[callout icon=”hb-moon-bike”]When your “efficiency factor” shows an upward trend or plateau, you’re ready for your next phase of training[/callout]


The efficiency factor feature is really just performing a simple calculation. It is your average power divided by your average heart rate. Essentially, it shows you whether or not your heart is doing a good job of keeping pace with the power that you were dishing out. What you should notice as a trend over that 6 to 12 weeks, is your efficiency getting a little bit better each time you ride.
Eventually, you will see that number begins to plateau. When it does, congratulations. You’ve put in enough time and enough miles to say you have developed an appropriate level of aerobic fitness. In other words, your cardio pulmonary engine is now more than adequate for Zone 2, and is ready for taking on the harder efforts of race-specific training.

What if you don’t have a power meter?

Without a power meter, you can still use your heart rate monitor, or even just RPE (rate of perceived exertion.) To use RPE, you’ll want to keep a written log of your base rides, and just giving them a difficulty rating on a scale of 1 – 10. What you’re looking for is a “leveling off” of exertion. You’ll be comparing your average speed to your Zone Two heart rate. As you see your speed getting a little bit faster while remaining in Zone Two steadily throughout your rides, you’ll know that you are reaching a plateau.

Clearly the trick here is to stay steady within Zone Two. That doesn’t mean that you can’t climb or put in the occasional sprint. (As a matter of fact, weekly seated climbing sessions is a great idea for base training.) But what you don’t want to do is work yourself too hard while trying to build a base. High-intensity workouts will ultimately thwart what you’re trying to do, because they will take more recovery.

Take your time. Be patient. Keep it easy to moderate. And keep an eye on that efficiency factor, or speed as it relates to a Zone Two heart rate. Assuming you’re going out for enough rides, or spending enough time on the turbo trainer, you will begin to see that efficiency factor or speed increase.

That’s when you can begin working on your specific race fitness, or build period.


[icon_box icon=”hb-moon-bike” icon_position=”left” align=”left”] Question: What is your recipe for a completed base period? Time on the bike? A certain number of base miles? Or do you measure your “EF?” Let us know, below.[/icon_box]

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Sam Lowe

I've been a road cyclist with a penchant for speed ever since my first-ever paycheck holiday. I blew the whole wad on a turquoise Schwinn Tempo with then-new Shimano 105 indexed shifting way back in 1985. I've been a voracious consumer of racing-oriented information ever since. Training, nutrition, bike fit, racing techniques, and all manner of "kit." Between nearly 30 years of riding, racing, and reading about racing, I'm ready to help you get ready to race.

  • Mike

    Shouldn’t you do a decoupling test to figure out if your done with base training?

    • Decoupling — for those who aren’t familiar with the term — is a measurement for when one’s heartbeat begins to drift over an extended effort. TrainingPeaks and Golden Cheetah both measure this, and it requires both a power meter and a heart rate monitor.

      My specific answer to your question, Mike, is this: if you have both a power meter and a heart rate monitor, by watching your EF, or Efficiency Factor over a series of Zone2 HR-guided efforts, you’re essentially monitoring your decoupling. Your EF should begin to steadily increase over several weeks. Once it levels off, or “plateaus,” you’re ready for regular interval efforts.

      If you don’t have a power meter, but do have a heart rate monitor, you want to keep track of your Average Speed over those Z2 HR rides. Assuming you’re keeping the efforts steady throughout the ride, you should see the average speeds increase…and then, just like one’s EF, they should begin to plateau. Time for intervals.

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