I think PI Amfibs are great, and they've kept my legs very comfortable in temps down to the teens. They are one of the few articles of cycling gear that I would replace without even comparing other products if they wore out. I used to think they were too warm in temperatures warmer than the 30s F. However, I've found that they are comfortable for me up through the 50s if I just moderate my level of exertion. If you are hammering it, you will probably sweat lot in warmer temps tho. I bike commute year-round, and one of the issues commuters face is cold temps in the mornings and much milder temps in the afternoons. So I wear my Amfibs a lot in winter with morning temps are in the 10s-30s, with afternoon temps in the 40s-50s. My legs get burned out if I ride hard every day commuting, so the Amfibs are very comfortable in the 40s and 50s at the pace I'm usually riding in afternoons.