So what is a good way to start interval training? I have some flat land so that is fine though mostly ups and downs where intervals may be tougher. What time ranges are you guys using? I have read all sorts of different things- from 30 seconds to 4 minutes of 90% and then 1 min to 5-6 mins of 50% effort, with 4-6 repetitions and 4-6 sets.