Details Sanremo 3 Thermosuit While protection during cold-weather cycling and aerodynamics are usually thought of as mutually exclusive, in which case we'd gladly sacrifice wind-stopping power and insulation to a bit of drag, leave it to the experts at Castelli to buck convention with its Sanremo 3 Thermosuit. After all, it was quite instrumental in bringing speedsuits to the pro peloton and its revolutionary Gabba jersey to the classics. We want to go fast all year long, so we can totally get behind a kit designed to slice through the wind with a streamlined fit, removing the constraints of bib straps, all while preserving the stalwart benefits achieved through the company's flagship cold-weather apparel. The Sanremo 3 places fabric panels at strategic locations to create ideal climate zones across your body while in the cycling position. The Windstopper X-Lite plus and 150 fabric is the first layer of defense against the chill on the upper portion, offering up 1.4 billion impossibly small pores per square inch that keep body heat in and let moisture and water vapor out. This isn't just based on vague marketing copy, though; the science behind Windstopper X-Lite is measurable in a rating called CFM, which stands for cubic feet per minute, used to measure the volume of air that passes through a fabric in—you guessed it—one minute. In order to be deemed "windproof," a fabric must register a CFM of equal to or less than 1.0. The Windstopper X-Lite fabric actually beats this rating, so you're virtually guaranteed a windproof top. The bottom portion is a mix of Thermoflex and Thermoflex Core2, using the former for areas that need more stretch, think the thighs and the back of the legs, and the latter in areas that need more protection like the front and knee area. Both versions of Thermoflex use hollow-core yarn to provide more insulating pockets of air as well as the ability to better wick away moisture. The whole Thermosuit is lined with a brushed fleece interior that sits softly against your skin. The Sanremo construction provides the same bulk-free, race-worthy fit you'd enjoy while wearing Castelli's Perfetto jacket and Sorpasso Bib Tights, but in one package that eliminates the possibility of draft inducing gaps. Cold weather bibs are often unduly constrictive on cold-weather items because of their focus on insulation rather than flexibility, so doing away with them is a plus, and the fact that the Sanremo 3 is a suit means that there are no unfortunate gaps in coverage at the waist. The cut is optimized for an on the bike fit and its fit is forward-oriented, so the Thermosuit might feel a little tight across the chest while you're standing, but it relaxes into a comfortable fit while you're stretched to the bars on your bike. The icing on the cake is the Progetto X2 Air chamois providing comfort on the longest base mile rides and you've got what's arguably one of the most comfortable cold-weather cycling kits we've tried. We honestly have no regrets riding into the colder months with top notch gear like this. The final details that round out the Sanremo 3 include a tall collar for extra warmth, three rear pockets to haul riding essentials, and YKK ankle zippers offering a secure fit and provide easy entry and exit from the garment with GIRO3 elastic and reflective zip covers to help increase your visibility to motorists in low-light conditions. The recommended thermometer rating for the Sanremo 3 is between 39 and 57 degrees. Anything lower than that might necessitate a warmer base layer or an additional outer shell. An insulated bodysuit for cold-weather cycling Windstopper membrane shuts the door on winter weather Lightly brushed lining insulates and wicks moisture Sanremo construction eliminates gaps between jersey and tights Its slim fit mimics an aero summer-weight racing kit Reflective details boost visibility in low-light conditions Recommended for use into the mid-30s Item #CST00NB Tech Specs Material [upper] Gore Windstopper X-Lite, [bottom] Thermoflex, Thermoflex Core2 Fit Form-Fitting Zip Full-Length Season winter, spring, fall Pockets 3 rear Reflective accents Recommended Use road cycling Manufacturer Warranty 1 year