Puro 3 Jersey

At our headquarters in Northern Utah, the range of temperatures where a thermal jersey like Castelli's Puro 3 Jersey ranges from October through March. Castelli recommends it for temperatures down to 57 degrees Fahrenheit; however, we find that, as long as temperatures stay north of 45, we often only need a light baselayer and a little sunshine to stay perfectly comfortable in the saddle—especially during early spring intervals or those unseasonably warm afternoons in mid-November.

When the temps (or the precipitation) do fall, the Puro 3 transitions to full-on winter when layered under a wind- and waterproof shell or rain jacket, adding thermal insulation to anti-weather pieces. Before the jacket comes out, the Puro 3's increased reflective zones help ensure you'll stay visible while squeezing out every last bit of daylight on early fall evenings.

The secret to the jersey's versatility lies in Castelli's use of Warmer fabric, which now extends across the entire jersey. Previous generations used a lighter material on the sleeves, which stretched more but insulated less and often left our arms—already exposed—with less protection than our heat-generating core. Increasing insulation on the arms reduces heat lost in extremities and, by extension, heat lost at the core through blood circulation.

• A thermal jersey for chilly rides and winter layering
• Insulating fabric provides warmth and breathability
• Streamlined fit layers under anti-weather shells for winter
• Gripper elastic and dropped hem reduce risk of riding up
• Three rear pockets stow essentials
• Larger reflective panels increase visibility in low-light conditions