Layering is best. I prefer warmer jerseys. Jackets (shells & thicker jackets) will usually leave me too warm. My HR is higher and we have a lot of climbs so that is mostly it....especially climbing makes me hot and sweat. Even in 40 degree weather, I cannot climb or ride hard with a jacket. At most, I wear a vest. You will have to test this out. Yeah, I probably have too many great jackets that I hardly wear.