Originally Posted by Machka

I believe that you lose weight when you sweat ... it's called dehydration. I can ride a century on a hot day and lose 2 or 3 lbs if I don't drink enough.

As for real weight loss, however, how much you sweat is just incidental.

Do you keep track of how much you cycle year round?

If you cycle less frequently and/or for shorter distances in the winter, you burn fewer calories. If you cycle more frequently and/or for longer distances in the summer, you burn more calories.