I often use "zone 1, zone 2, 3, 4, 5" when I post workouts.....It is especially helpful with the bike training because there is so much stopping and starting when you go out for rides....So, I like to keep it simple and have my athletes...work on "perception."
Zone 1 - recovery - easy - could go forever, getting body moving, flushing out the muscles from a hard effort
Zone 2 - breaking a sweat, getting heart rate up, but, no more then you would on a long run
Zone 3 - working into lactate threshold...about how you would feel racing a 15k to a half marathon
Zone 4 - you're working and you can sustain for no more then 30-50 minutes..5k-10k race pace perception
Zone 5 - Interval Pace - hard effort....short bursts....up to 5k race pace....
I hope this helps.....Maria