Calculate your Joe Friel cycling heart-rate zones as a percentage of your lactate threshold heart rate (LTHR). Enter your LTHR and get all seven zones (including the 5a/5b/5c threshold splits) instantly.
The Friel heart-rate zones
| Zone | Name | % of LTHR |
|---|---|---|
| Zone 1 | Recovery | Up to 81% |
| Zone 2 | Aerobic | 82–89% |
| Zone 3 | Tempo | 90–93% |
| Zone 4 | SubThreshold | 94–99% |
| Zone 5a | Threshold | 100–102% |
| Zone 5b | Aerobic Capacity | 103–106% |
| Zone 5c | Anaerobic | 107%+ |
How to find your LTHR (Friel method)
Friel’s field test: warm up, then ride a 30-minute all-out time trial on your own. Start your average-HR reading 10 minutes in, and use your average heart rate for that final 20 minutes as your LTHR. Friel zones are then set as a percentage of that number.
FAQ
What is LTHR in the Friel system?
Lactate threshold heart rate — your average HR for the last 20 minutes of a 30-minute solo time trial. Friel’s zones are percentages of it.
Why does Friel split Zone 5 into 5a, 5b, 5c?
To give finer control over the hardest efforts — threshold (5a), aerobic capacity / VO2 (5b), and anaerobic (5c) each drive different adaptations.
Friel vs. Coggan heart-rate zones — which should I use?
Both are well-established. Friel’s seven-zone system gives more granularity at the top end; Coggan’s five-zone HR set is simpler and mirrors his power zones. Pick the one your training plan uses.
Zones based on the published methodology of Joe Friel — The Cyclist’s Training Bible.
More: all training-zone methods in one calculator · Coggan power · Coggan HR · Friel HR · Max-HR