Think of FTP as your running threshold pace, but measured in watts. If you understand pacing in running, you already understand power on the bike — it's just a different unit for the same concept.
That's the whole article, honestly. Everything below is detail. But the detail matters, because runners arriving in cycling keep making the same two mistakes: treating power like a foreign language when they're already fluent in the underlying idea, and panicking when their first FTP test spits out a number that seems insultingly low for someone who can run a 42-minute 10K.
Both are fixable in the next ten minutes.
What FTP actually is
FTP stands for Functional Threshold Power: the highest power output you can sustain for roughly an hour. Power is measured in watts — the actual mechanical work you're putting through the pedals, captured by strain gauges in the crank, pedals, or rear hub.
Here's the running translation. You have a pace you could hold for about an hour of racing — for most club runners, somewhere between 10K pace and half-marathon pace. That effort sits right around your lactate threshold: the intensity where lactate production and clearance balance on a knife edge. Go slightly harder and you're on borrowed time. Sit slightly below and you can hold it improbably long.
You already train around this marker. Tempo runs sit just under it. Threshold intervals sit at it. Your coach — or your training app — anchors half your sessions to it.
FTP is exactly that, in watts. If you can run 10K at 4:30/km, that's your "running FTP" — the sustainable ceiling for around that duration. A cyclist saying "my FTP is 250" is making the same statement as a runner saying "I can hold 4:30s for the hour." Same physiology, different unit.
Why watts instead of speed? Because speed lies on a bike. A 20mph ride into a headwind and a 20mph ride sitting in a group are wildly different efforts — drafting alone can halve the work. Add gradients and road surface, and speed becomes almost useless as a training measure. Running speed is a reasonably honest proxy for effort; cycling speed isn't. Watts cut through all of it: they measure what your legs are doing, not what the wind is doing. The full case for training with power is in the power meter training guide.
Why your first FTP will be "low" — and why that's fine
Now the part that dents egos.
You do your first FTP test expecting your years of running fitness to show up. The result: 150 watts. You look up what that means and discover it's... modest. Meanwhile your VO2max is 55 and you've got a marathon PR that turns heads at the club.
Nothing is wrong with you. Nothing is wrong with the test. What's happened is that FTP measures two things at once — your aerobic engine and your cycling-specific muscular endurance — and you've only trained one of them.
Running built you a serious engine: high cardiac output, expanded plasma volume, dense mitochondria. All of that transfers to the bike, and the fitness transfer research confirms it. What running did not build is the peripheral machinery cycling demands: quadriceps that can produce force 90 times a minute for an hour, glutes that drive a seated pedal stroke, the neuromuscular pattern of pushing through a circle rather than bouncing off the ground. Your quads don't know what they're doing yet. Genuinely — the coordination isn't there, so a chunk of your effort is being wasted before it ever reaches the rear wheel.
The tell is in how the test feels. Most runners finish their first FTP test with burning legs and breathing that never got past conversational. Their cardiovascular system never got to play — the untrained cycling muscles tapped out first. If that was your experience, it's the clearest possible evidence that your ceiling is far above your current number.
And this is where being a runner pays off. A true beginner has to build the engine and the drivetrain. You only need the drivetrain, and muscle adapts faster than engines get built. Runners consistently gain 15-25% FTP in their first three months of structured riding — improvement rates that make established cyclists mutter into their coffee. The 150 becomes 185 by autumn without heroics, just consistent riding.
The zones: you already know these efforts
Cycling organises training into power zones anchored to FTP. The names are new. The sensations are not — you've felt every one of them on a track or a tempo loop.
Zone 1 — Active recovery (under 55% of FTP). The effort of a genuine recovery jog. Embarrassingly easy, deliberately so.
Zone 2 — Endurance (56-75%). Conversational pace. Your easy-run effort: full sentences, nose-breathing possible, could continue for hours. This is where the bulk of your riding should live, same as your easy running mileage — the Zone 2 guide explains why coaches from Dan Lorang to Professor Seiler build everything on this foundation.
Zone 3 — Tempo (76-90%). Comfortably hard. Marathon-to-tempo-run effort: speaking in phrases, concentration required, sustainable but not casual.
Zone 4 — Threshold (91-105%). Race effort. Your 10K-to-one-hour intensity — the FTP zone itself. Short sentences only. The same controlled discomfort as a hard tempo session.
Zone 5 and above — VO2max and beyond (106%+). Interval pain. Three-to-five-minute repetitions at 3K-to-5K effort, then shorter, sharper work above that.
Read that list again and notice what happened: you already know how to pace every zone. Twenty years of running taught your body these efforts with a precision no beginner cyclist has. The wattage number just puts a number on what your legs and lungs already understand. That perception is a genuine head start — you'll feel when a "Zone 2" ride drifts into Zone 3 the way you feel an easy run creeping toward tempo.
How to test it
Two standard protocols, both available on Zwift, TrainerRoad, or with any power meter and a stretch of quiet road.
The 20-minute test. Warm up properly — 15-20 minutes with a few hard surges. Then ride 20 minutes as hard as you can evenly sustain. Multiply your average power by 0.95: that's your FTP. The pacing challenge will feel familiar — it's a 5K race. Start a touch conservative, hold through the grim middle ten minutes, empty it over the last five. Runners who've raced know exactly how to do this; the only trap is going out at "20 minutes can't be that bad" power and detonating at minute eight. It can be that bad. Respect it like you'd respect a 5K.
The ramp test. Power increases every minute until you can't turn the pedals anymore, and the software back-calculates FTP from where you failed. No pacing judgment required, over in about 25 minutes, considerably less dreadful. For runners new to cycling I'd point you here first — pacing a maximal 20 minutes in a sport where you don't yet know your body is genuinely difficult, and a badly paced 20-minute test gives you a junk number.
Retest every six to eight weeks in your first year. Your FTP will be climbing fast, and stale zones mean every session is slightly too easy.
One practical note on equipment. You need something that measures power: a smart trainer indoors (which is where most runner-cyclists start, and where Zwift and TrainerRoad live) or a power meter on the bike itself for outdoor riding. If you're choosing one, the smart trainer wins for a runner's first year — controlled conditions, no traffic, no junctions interrupting an interval, and the test protocols are built into the software. Heart rate alone can approximate zones, but it drifts with heat, fatigue, and caffeine in ways power doesn't, and it lags every change of effort by a minute or more. Watts respond instantly. That immediacy is what makes power the standard.
Translating your running sessions to the bike
Once your FTP is set, your entire running library translates almost session for session. This is the part most new cyclists take years to piece together, and you get it on day one.
Your easy run becomes a Zone 2 ride — 60 to 90 minutes at 56-75% of FTP, conversational throughout. Your tempo run becomes 2-3 blocks of 15-20 minutes in Zone 3. Your threshold session — say, 3 × 10 minutes at 10K effort — becomes 3 × 10 minutes at 95-100% of FTP with five minutes easy between. Your VO2max session of 5 × 3 minutes hard maps to 5 × 3 minutes at 110-120% of FTP. Even the structure of your week transfers: hard days hard, easy days easy, one long session, the polarised shape that every credible endurance programme shares.
Two adjustments, though. First, expect to spend proportionally more time in Zone 2 than you might have run — cycling tolerates and rewards bigger easy volume because there's no impact cost, and the long steady ride is the sport's equivalent of your long run. Second, add duration rather than intensity when sessions start feeling manageable. The runner's instinct is to push pace; the cyclist's gains in year one come mostly from riding more, at the right efforts, and letting the cycling-specific muscle build underneath the engine you already own.
What's a good number?
The question everyone asks, and the answer every coach gives: raw watts mean nothing without body weight. Two hundred watts from a 60kg rider and 200 watts from a 95kg rider are different animals the moment the road tilts up.
So cycling thinks in watts per kilogram. A 70kg runner holding 200W is at 2.86 W/kg — a solid platform for a new cyclist, comfortably clear of the untrained population. Cross 3.0 W/kg and you're in competitive amateur territory: fast group rides, respectable club racing. The 4.0+ range is where serious racing lives, and it takes years of specific work.
Fit runners tend to move through the lower rungs quickly, for the reason covered above: the engine is already built. Where you should sit for your age and background is covered in the FTP benchmarks guide.
There's a familiar shape to W/kg if you think about it for a moment: it's the same logic as age-grading or comparing runners by pace rather than raw speed on a hilly course. Cycling just formalises it, because on any road that goes up, power-to-weight is what decides who arrives first. On the flat, raw watts matter more — aerodynamics and absolute power rule there — which is why a 90kg rider with a big engine can bury everyone on a flat road and then go backwards on the first real climb. Know which terrain you're judging yourself on before you decide what your number means.
Don't chase the number
One warning before you go, because runners are especially prone to this.
You come from a sport where the number is the result. Your 10K time is the point. So the instinct is to treat FTP the same way — a score to be raised, tested monthly, compared at the café stop.
Resist it. FTP is not your race result; it's a measuring stick that makes your training accurate. Its job is to set your zones so that easy rides are actually easy and hard sessions hit the right dose. That's it. Riders who chase the test number end up doing their easy rides too hard — the classic grey-zone trap — and stagnate exactly the way runners who race their easy days do. You've seen that guy at the club. Don't become his cycling equivalent.
The goal is to ride well: to finish the group ride strong, climb without blowing up, and still be improving in five years. The biggest FTP in the group is a trivia answer. Put the number in your head unit, build your weeks around it — the training plan structure guide shows how — and then stop thinking about it between tests.
You spent years learning that patient, structured training beats heroics. Cycling obeys the same law. You're further ahead than your first test number says — and by the time the second test rolls around, the number will have started saying it too.