Well, when it's about 40-45 outside and I want to wear shorts and a short sleeve jersey, I use DZ Nuts InHeat High Heat.Now, I'm telling you right now, this is REALLY hot and it will linger for hours. Also, when you take a shower, well it's going to be rather interesting if you're not used to using this strength. However, use it sparingly in the right spots, and it'll allow you to get by without much on. They also make a medium heat that I use when it's 50-55 outside and a low heat that I use just around my knees when it's between 60-65 outside. You can get all these at Amazon, Real Cyclist, etc. The above recommendation for Mad Alchemy is solid as well.