+1. Icebreaker merino wool tops are the dog's danglies. I have two, and find them brilliant for staying non-whiffy, wicking and drying quickly, as well as being presentable enough to wear to work. They pack down small too, so I use them when I'm touring on the motorbike, but I've never really thought of wearing them for cycling. They seem to keep you warm when its cold and vice versa, due to some crazy New Zealand sheep voodoo. But they're £50 for a teeshirt.