The Medio LS Base Layer from Castelli is a mid-weight long-sleeve baselayer rated for an ideal range of 39 to 57 degrees Fahrenheit, which places it squarely in cool-to-mild conditions rather than deep winter. Within that range it wicks moisture, regulates temperature, and keeps you comfortably dry under your jersey. If most of your riding falls in that cool-but-not-freezing window, the Medio LS Base Layer gives you moderate insulation without the bulk of a heavier thermal layer.

The Medio LS Base Layer from Castelli suits riders heading out in cool-to-mild cold-weather conditions, roughly 39 to 57 degrees Fahrenheit, who want a foundational layer that manages moisture and regulates temperature. Its mid-weight polyester stretch fabric provides moderate insulation, so it works well when a jersey alone isn't quite enough but full winter warmth would be too much. Riders who prioritize staying dry on cool rides tend to find the Medio LS Base Layer a dependable first layer under a long-sleeve jersey.

The Medio LS Base Layer from Castelli is rated for 39 to 57 degrees Fahrenheit, which means riding below that range will leave you underdressed. It's a mid-weight baselayer built for cool-to-mild conditions, not sub-freezing cold. If your rides regularly drop into the 20s and 30s, consider the Flanders 2 Warm Baselayer instead, and for extreme cold the Active Extreme Baselayer offers maximum thermal protection. Matching the baselayer to your actual ride temperature is what keeps you comfortable and dry.

The Medio LS Base Layer from Castelli delivers moderate, mid-weight insulation tuned for 39 to 57 degrees Fahrenheit, so in milder conditions you may find it adds more warmth than you need. If your rides fall just above that range and you want lighter insulation under your jersey, the Flow LS Baselayer Top is a better match. The key distinction is how much warmth you want from your first layer: the Medio LS Base Layer is for genuine cool weather, not transitional mild days.

The Medio LS Base Layer from Castelli is designed as a first layer that sits against the skin, wicking moisture away before it chills you and regulating temperature across your ride. A warmer jersey alone traps sweat without managing it, while the Medio LS Base Layer keeps you comfortably dry in cool conditions. Its mid-weight polyester stretch fabric layers close under a jersey, so you get moisture control plus moderate insulation without extra bulk. The right baselayer is the foundation of a comfortable cold-weather ride.

The Medio LS Base Layer from Castelli has an athletic fit, meaning it sits close to the body so it can wick moisture effectively and layer smoothly under a jersey. A close fit matters for a baselayer because fabric needs skin contact to move sweat away and regulate temperature. If you prefer a looser feel, Castelli recommends sizing up. With a 25-inch sleeve length and a crew neck collar, the Medio LS Base Layer is built to stay in place and layer cleanly on cool-weather rides.

The Medio LS Base Layer from Castelli is made from 100% super-soft polyester stretch fabric in a mid-weight construction, which delivers moderate insulation rather than the heaviest warmth in the baselayer lineup. In practice that means it adds meaningful warmth for cool-to-mild rides in the 39 to 57 degree Fahrenheit range while still breathing and wicking moisture. Mid-weight is a deliberate middle ground: enough insulation for genuine cool weather, light enough that you won't overheat the way you would in a thermal winter baselayer.

The Medio LS Base Layer from Castelli is a mid-weight, moderate-insulation layer rated for 39 to 57 degrees Fahrenheit, so it's built to add warmth rather than shed it. In warm conditions you'd likely overheat in this fabric. If your goal is a wicking layer that manages moisture and airflow in warm weather, a sleeveless mesh option like the Pro Mesh Sleeveless Baselayer is the better fit. Choose the Medio LS Base Layer when the temperature genuinely calls for cool-weather insulation under your jersey.