FTP power zones

What FTP is

Functional Threshold Power is the maximum power you can hold for about an hour: the reference for all power-based training. Estimate it with the classic 20-minute test: 20′ average × 0.95 (the standard convention, applied and declared by the tool).

The 7 zones

Z1 recovery (<55%), Z2 endurance (56-75%) where the base is built, Z3 tempo (76-90%), Z4 threshold (91-105%) to raise FTP itself, Z5 VO2max (106-120%) for the aerobic engine, Z6 anaerobic (121-150%) and Z7 sprint. Each zone trains a different system: most miles go in Z2, quality in Z4-Z5.

W/kg, the number that climbs

Uphill, power gets weighed: 250 W is 3.6 W/kg at 70 kg and 3.1 at 80. That's why absolute FTP rules flat time trials and W/kg rules the climbs.

Note

Coggan percentages, the de facto standard for twenty years (same as bike computers and training platforms). FTP tracks your form: retest every 6-8 weeks and recompute the zones.

Why watts replaced heart rate

Power is a measure of what you are doing, heart rate of how the body is reacting. The difference is enormous in practice: watts are immediate, while heart rate lags by tens of seconds and shifts with heat, sleep, caffeine, stress and accumulated fatigue.

On a thirty-second effort the heart rate monitor has no time to climb, and on a climb on a bad day the same effort shows a different pulse. It is why modern road training uses watts as the reference and heart rate as a control signal: when the two diverge, it is usually the body saying something.

The twenty-minute test, and its tricks

FTP is defined as the power sustainable for about an hour, but hardly anyone does a full hour flat out: you ride twenty minutes and take 95% of the result. The coefficient is not arbitrary, it is a statistical correction, and like every average it errs at the extremes: riders with great endurance come out underestimated, explosive ones overestimated.

The way to ruin the test is always the same: starting too hard. The first five minutes feel easy, and the second half collapses; the result is an FTP lower than the real one and training set to the wrong numbers. A successful test has a second half equal to or slightly higher than the first, which is why it is done after a serious warm-up and on a route without interruptions.

Zone 2, that is the zone almost everyone skips

It is the zone where the aerobic base is built, and it feels too easy to be useful: you breathe normally and can talk. Precisely for that reason almost everyone rides it harder, ending up in a middle ground that tires without training either endurance or threshold — what coaches call the grey zone.

The distribution nearly every programme proposes is the one seen among professionals: about eighty per cent of the time in zones 1 and 2 and the rest hard. Riders with few hours a week can raise the intense share, but the principle does not change: easy sessions have to be genuinely easy, or the hard ones do not come off.

When FTP stops being the right number

In road races, where what counts is not average power but how many times you can repeat an effort above threshold: two riders with the same FTP can have completely different capacities to survive attacks. It is why more recent models also describe the reserve above threshold.

And on long climbs, where the ratio between power and weight rules: 300 watts is 4.3 W/kg for a seventy-kilo rider and 3.5 for an eighty-five-kilo one, and uphill the difference is enormous. On the flat, where air resistance dominates, absolute power counts instead, which is why big riders go fast against the clock and small ones in the mountains.

Nearby tools

For the mechanical side there is Bike gearing, for heart rate Heart rate zones and for consumption Calories burned. For weight and composition Body fat calculator.