THAT'S what that smell is, huh?
During the summer, by far, the stinkiest items are a) my gloves and b) my helmet, especially the forehead pad. I wash both -- that is, the gloves and the forehead pad -- once a week along with the rest of my biking clothes. Cold water, woolite, dry on low heat. Keeps things smelling presentable.
However, I find with washing that the velcro attachment on the helmet pads starts to go. What do others do?