I'm using it to track my rides and have noticed a consistent difference between when riding on the trails and on my trainer. For example I'll ride 22 miles and show right around 1250 calories with an average 115 bpm heart rate at an average cadence of 72. When on the trainer riding 20 miles with an average 120 bpm and cadence of 80 and it shows around 700 calories. Am I missing something?

Rich