i worked out on a stationary bike at the gym. I chose the weight loss option which goes up in intensity, gets harder and easier in intervals, and then goes down in intensity. it is a 30 minute seting. So i rode the bike in this setting for 30 minutes. The display said that I rode 6 miles and burned 60 calories; however, on the internet riding on a stationary bike is listed as at least 250 calories. Which is right?