I always either gain a pound or two when I ride long or stay the same. I lose a couple of pounds when I do my twenty mile training ride. I think it has to do with liquid intake. I'm much better on a long ride about staying hydrated and I don't push myself as hard. My heart rate average on the short ride is 10 - 15 beats per minute higher.

In any case neither the pounds gained nor the pounds lost stay that way for more than a day or two.

V.