To burn more fat when riding your bike, the answer is simple: intervals
- Spend about 15 minutes riding your bike as a warm up.
- The give her all you've got by blasting your bike hard for 60 seconds. Your target should be about 90% of your maximum heart rate.
- Ride at a recovery rate for two minutes.
- Repeat this interval ten times.
- Cool down by riding at the recovery rate for at least 10 minutes.
You can build up to doing 20 intervals for a great workout.
Source: About: Bicycling website