Is there anyone on here who has lost weight mostly from using an excercise bike?

I ask because a good 85% of my cardio is based solely on the exercise bike...I burn 600 ( in 30 minutes ) in the morning and 600 in the evening..I'm a little worried about 600 in 30 minutes...could this be an error in the machine or something? My speed is 20-21/hr...just sounds too good to be true when I hear people say it takes them like an hour to burn 500/600 calories. And is the treadmill a better form of cardio or is the bike jus as effective?

Thanks in advance

wow, that's a lot. i've never heard of that much in a half an hour on an exercise bike, but keep it up, that's awesome.

oh, and the treadmill is a little better because you're standing up, working your butt a little more, but the bike is really similar and you're still burning A LOT of calories.