It may not have anything to do with the distance, or the heat.

Mine commutes -- it's a ten mile ride each way for him, and he does it rain, shine, heat, cold. I work sporadically, and usually have LOTS to carry, so most of the time, I drive, even though it's much closer than his ride.

BUT, because it's fun, sometimes I ride to meet him for his ride home. This makes him CRAZY! It's not distance, it's not weather, it's TRAFFIC. Even though it's FINE for him to ride in traffic, it's not okay for ME to ride in the very same traffic. I should ride south of town, through the residential areas to the grocery store if I insist on riding alone!

Yeah, it makes me crazy too!

Karen in Boise