Tool 02 · Heart-rate zones
Know your zones.
A five-zone chart for spin days: keep the easy rides easy, make the hard efforts honest, and stop guessing what “steady” means.
Your numbers
14–90 years
BPM, measured at rest · default 60
Max HR = 208 − 0.7 × age. Zones use the Karvonen formula with your resting heart rate.
Estimated max
184bpm
Built from age 35 and a resting heart rate of 60 bpm.
- Z1Easy / recovery50–60%122–134bpm
- Z2Steady60–70%134–147bpm
- Z3Aerobic70–80%147–159bpm
- Z4Threshold80–90%159–172bpm
- Z5Hard / max90–100%172–184bpm
Most spin classes move between Z2 and Z4. If you can hold a conversation, you are lower. If you can only manage a word, you are higher.
Estimates only. These zones come from a formula, not a lab test — ask a coach before training to a number.
The math
Two formulas, five ranges.
Estimated max heart rate.The calculator uses 208 − 0.7 × age. It is a population estimate, not a measured maximum. A field test or a lab test is more personal.
Karvonen zones.Each zone is resting heart rate + (max − resting) × intensity, from 50% to 100% in five bands. That is why the resting number matters as much as the age.
What the zones mean in the room.Z1–Z2 is conversation pace. Z3 is steady work. Z4 is hard but repeatable. Z5 is short and maximal. Most spin classes move between Z2 and Z4.
Use the talk test too.If you can speak in full sentences, you are probably lower than you think. If you can only say one word, you are higher. The chart is a guide, not a coach.
Put it to work
Bring the zones to a ride.
Spin is the cardio room at Activate House: music-led, instructor-cued and open to all levels. The two-week unlimited offer is $99 at North Park and $89 at Bird Rock.