CoachingAnswer

HOW DO I TEST MY FTP ACCURATELY?

By Anthony WalshRoadman CyclingUpdated 25 May 2026

WHO THIS IS FOR

IS THIS YOU?

The self-coached rider

You set your own zones and need a defensible, repeatable testing protocol.

The rider whose zones feel off

Your intervals feel mis-targeted and you suspect an old or bad FTP number.

THE ROADMAN VIEW

Most riders obsess over which test to do and ignore the thing that actually decides accuracy: the state of the body taking it. A 20-minute test on a fatigued Friday after a hard week will read low, you'll set your zones too soft, and every session for the next eight weeks will be slightly mis-targeted. The protocol matters far less than the prep.

The two honest options are the 20-minute test (warm up properly, ride 20 minutes as hard as you can hold evenly, take 95% of the average) and the ramp test (shorter, less mentally brutal, but it can read differently for some riders). Either is fine. What's not fine is switching between them and comparing the numbers, or testing without a real warm-up and a fresh body.

And testing isn't free — it costs a hard effort and a recovery day. So don't do it every four weeks. Test at the end of a block, ideally after an easy week, when your body can actually express the fitness it built. The number you get rested is the number worth training off.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Joe FrielAuthor of The Cyclist's Training Bible
Formal testing belongs at block boundaries, not mid-block, and the prep — warm-up and a degree of taper — is what separates a real FTP from a fatigued one. Fewer high-quality tests beat more low-quality tests.
Hear it: Joe Friel's Cycling Training Plan Structure | Roadman Cycling
Roadman on training distributionRoadman podcast — 80/20 with Seiler
An accurate FTP is only useful if your zones are then applied honestly. The point of testing isn't the number — it's calibrating the easy and hard work so the distribution actually does its job.
Hear it: 80/20 Training to Ride Faster | Dr Stephen Seiler

PRACTICAL APPLICATION

DO THIS WEEK

Arrive rested
Take an easy day or two before testing. Testing on fatigue is the most common way amateurs underestimate FTP and set their zones too low.
Warm up properly
15–20 minutes building from easy spinning, with a couple of short openers near threshold. A cold start wrecks a 20-minute test in the first five minutes.
Pace it evenly
On the 20-minute test, ride a steady hard effort you can hold — don't start at 110% and fade. Take 95% of your average power as your FTP estimate.
Lock your protocol and cadence
Use the same test, indoors or out, each time. Comparing a ramp test to a 20-minute test, or an indoor number to an outdoor one, isn't a like-for-like comparison.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKETesting on a fatigued day mid-block.
FIXTest rested, at block-end, ideally after an easy week. Fatigue can understate FTP by 5% or more.
MISTAKESwitching between ramp and 20-minute tests.
FIXPick one and stick with it. The two protocols can produce different numbers, so mixing them hides real change.
MISTAKEStarting the 20-minute effort far too hard.
FIXPace evenly. A fast start that fades gives a lower, less accurate average than a steady, sustainable effort.

FAQ

FREQUENTLY ASKED QUESTIONS

Should I do a ramp test or a 20-minute test?

Either, as long as you're consistent. Ramp tests are shorter and less mentally taxing but can underestimate FTP for some riders. The 20-minute test is more demanding and slightly more accurate when paced well. Pick one and keep using it.

Why do I take 95% of my 20-minute power?

Because FTP is defined as roughly the power you could hold for an hour, and 20 minutes all-out overstates that. The 5% reduction approximates the drop-off from a 20-minute effort to a true one-hour sustainable power.

How often should I test FTP?

Every 6–8 weeks, ideally at the end of a training block. Testing every 4 weeks is too aggressive — mid-block fatigue masks gains. Testing once or twice a year is too rare — your zones drift and your training intensity becomes guesswork.

Is an indoor or outdoor FTP test more accurate?

Neither is inherently more accurate, but they often produce different numbers — indoor power can read lower due to heat and lack of cooling. Test in the environment you mostly train in, and don't compare indoor results to outdoor ones.

Can I estimate FTP without a formal test?

You can estimate from a recent hard hour or a race, usually within 5–10% of reality. That's fine for setting initial zones, but not precise enough for prescribing exact threshold or VO2max work, where 5% is the difference between adaptation and over-reaching.

Do I need to test FTP if I use TrainerRoad or similar?

Less often. Adaptive platforms infer FTP from session quality, so you may not need formal tests as frequently. Most coached athletes still run a periodic test every 8–12 weeks to sanity-check the algorithm.

RELATED EPISODES

HEAR THE CONVERSATIONS

Joe Friel's Cycling Training Plan Structure | Roadman Cycling

80/20 Training to Ride Faster | Dr Stephen Seiler

Heat Training for Cyclists: +30 Watts FTP | Roadman Cycling