VegasTriker

It is worthwhile as a comparison between different rides on different days but don't expect it to be an accurate calculation of calories burned. It is an approximation. It does not take into account the differences in efficiency between different bikes. A rider using a lightweight carbon fiber road bike doing 20 mph for an hour will not burn the same number of calories as somebody riding a much heavier and less expensive bike like a 45 pound Huffy. It takes a lot more effort to propel the latter to the same speed.

If you wish to lose weight, the answer is simple. Monitor your caloric intake and make sure it is somewhat less than what your body requires to maintain it's current state. It is pretty easy to automatically adjust for the calories burned while riding and then wonder why all of your effort does not result in losing weight.