Cycling & Triathlon
FTP and Cycling Power Zones Explained
Power is the most objective way to train and pace on a bike. This guide explains what FTP is, how to test it honestly, and how to turn it into a training structure that works.
Why power changed cycling training
Unlike heart rate, which lags and drifts, a power meter reports exactly how hard you are working the instant you push the pedals. That immediacy makes power the gold standard for both pacing efforts and measuring fitness, because the number cannot be fooled by heat, caffeine, or excitement.
The foundation of power-based training is a single figure: your Functional Threshold Power, or FTP.
What FTP actually is
FTP is usually defined as the power you can hold for about an hour, but the hour is a convention rather than the thing itself. What the number approximates is your lactate threshold: the intensity at which the lactate your muscles produce and the lactate your body clears stay in balance. Ride below it and you can continue almost indefinitely; ride above it and the imbalance compounds until you are forced to slow.
The hour is a convention. What FTP approximates is the intensity where lactate production and clearance stay in balance.
That physiology is why FTP anchors training in a way heart rate cannot. Heart rate describes your body's response to an effort, and it drifts with heat, caffeine, sleep and accumulated fatigue. Power describes the effort itself. Two rides at the same wattage represent the same mechanical work, whatever your heart happens to be doing that day.
Testing FTP honestly
An FTP test is only useful if you pace it well and give a genuine effort. Warm up thoroughly, then ride the 20 minutes as evenly as you can manage at the hardest pace you can hold to the end, not a sprint that fades. Going out too hard and crawling home produces a misleadingly low number.
Retest every four to eight weeks during focused training. More often than that mostly measures fatigue, and a stale FTP makes every workout slightly wrong.
Turning zones into an actual training week
Knowing the zone bands is the easy part — the FTP calculator lists each one's percentage of threshold. The harder question is which sessions to actually ride.
Two workouts carry most of the load for a time-crunched rider. Threshold intervals, typically two blocks of twenty minutes just under FTP, raise the power you can hold for a long time. VO2 max intervals, something like five efforts of three to five minutes well above threshold, lift the ceiling those longer efforts sit beneath. One of each per week, with every other ride kept genuinely easy, is a complete programme for most amateurs.
What quietly wrecks progress is the comfortable middle. Riding tempo feels productive and virtuous, but it banks real fatigue while returning less adaptation per unit of tiredness than either easy endurance or proper intervals. If you finish nearly every ride mildly tired, that is probably where you are living.
Power-to-weight and the bigger picture
Raw FTP matters on the flat, but on climbs what counts is power-to-weight, your watts per kilogram. A rider with a lower absolute FTP but a higher W/kg will often climb faster. Improving either your sustainable power or your power-to-weight, ideally by raising power rather than crash dieting, is the route to going faster.
Use FTP to set your zones, W/kg to gauge climbing, and consistent training in the right zones to move both in the right direction.