What Is the 75% Rule in Cycling? The Easy-Hard Split, Explained

The 75% rule in cycling says that about three quarters of your riding should be easy, and the other quarter can be hard. That's it. It is a rule of thumb, not a scientific law, and different sources phrase it slightly differently. But underneath every version is the same idea, and that idea is well supported by research: most of your riding should be comfortably easy, so that the hard riding can be properly hard.

Here is what the rule means, where it comes from, how it relates to the 80/20 rule, and how to use it in a normal week.

What the 75% rule actually says

You will find two common versions.

Version one: by time. About 75% of your weekly riding time is easy, low-intensity riding, and about 25% is harder work such as intervals, climbs ridden hard or fast group rides.

Version two: by heart rate. About 75% of your riding time is spent at or below 75% of your maximum heart rate, and the rest above it.

Both versions point the same way. Neither has a single scientific origin. The rule is a simplified, easy-to-remember take on a pattern researchers have measured in endurance athletes for decades: they do far more easy work than hard work, and they keep the two clearly apart.

Where the idea comes from: the 80/20 rule

The research behind it usually goes by a different number. Sport scientist Stephen Seiler reviewed how successful endurance athletes actually train and found that athletes training 10 to 13 times a week tended to settle on about 80% of their sessions at low intensity and about 20% dominated by high-intensity work (Seiler, 2010). That is the 80/20 rule, often called polarised training.

Two studies are quoted most often:

• Trained cyclists, six weeks each way. Twelve trained male cyclists did six weeks of a polarised plan (80% low, 0% moderate, 20% high intensity by time, about 6.4 hours a week) and six weeks of a threshold-focused plan (57% low, 43% moderate, about 7.5 hours a week). The polarised block produced greater physiological and performance gains, despite fewer hours (Neal et al., 2013).
• Well-trained endurance athletes, nine weeks. Forty-eight athletes, including cyclists, were split into four groups. The polarised group improved peak oxygen uptake the most, by 11.7%, and peak power by 5.1% (Stöggl and Sperlich, 2014).

So is it 75% or 80%? For most riders the difference doesn't matter. The 75% rule simply gives a little more room for hard work, which suits people who ride fewer hours. What matters far more is the principle both numbers share.

Why most of your riding should be easy

Easy riding builds the engine. Long, steady riding develops your aerobic base: the heart, the blood vessels and the muscles' ability to use oxygen. That base is what everything else is built on. Our guide to Zone 2 training covers this in detail.

Hard riding needs you fresh. Intervals only work if you can hit the target and hold it. If every ride is medium-hard, you arrive at your key sessions tired and ride them at medium-hard as well.

Drifting into the middle is the common mistake. Many riders let easy rides creep up to moderately hard, week after week, without meaning to. It feels productive, but it tires you out and leaves less energy for the sessions that are meant to be hard. Moderately hard riding has its uses, especially when time is short; it just works best as a choice, not a habit.

How to use the 75% rule in a real week

Take a rider with 8 hours a week:

• About 6 hours easy. You can hold a conversation. On a power meter this is well below threshold; by feel, it should seem almost too easy.
• About 2 hours of hard work, counted as the time spent in the hard efforts and the riding around them, usually across two sessions such as one interval session and one hilly or fast ride.

A few practical points:

1. Count by time, not by rides. A three-hour easy Sunday ride weighs more than a one-hour interval session.
2. Easy means easy. Most riders who think they follow the rule are riding their easy days too hard. Use heart rate or power to check, not feel alone.
3. Hard means hard. If you can chat during an interval, it isn't the hard part of your week.
4. Short on time? The rule bends. Most of the evidence for an 80/20 split comes from athletes training many hours a week. With fewer hours, a bigger share of harder riding, including sweet spot and threshold work, can make sense. Our piece on polarised versus sweet spot training looks at this trade-off for riders with limited time.

Common questions

Is the 75% rule the same as the 80/20 rule?

Does the 75% rule use heart rate or time?

Does the 75% rule work for beginners?

What counts as hard riding?

The short version

Ride most of your hours easy, keep your hard sessions properly hard, and choose your moderate riding on purpose rather than drifting into it. Whether you call it the 75% rule or 80/20, that balance is the part that makes you faster.