The auto calculators on Map My Tracks create recommended power zones based a threshold power value.
Establishing your threshold power
To establish your threshold power you can complete a simple but hard test. You'll need a flat road in a loop of 20-30 minutes long or using a turbo trainer.
- First warm up easy for 20 minutes.
- Don't start too quickly. Over five minutes gradually increase your effort every 30 seconds until you can only manage short sentences.
- Now start your power meter and hold the same effort for a further 20 minutes. Make a note of the average power for ONLY these 20 minutes.
- To establish your threshold power multiple the 20 minute average by 0.95. This is your threshold power.
Once you have established your threshold power use the calculator in the profile settings to create your five power zones.