Cold Days 2nd Baselayer - Men's

What Our Gearhead® Experts Are Saying:

"The Cold Days 2nd Baselayer is the piece I recommend to serious winter riders who have maxed out what a single base layer can do. Polartec Alpha is one of the best insulating fabrics available for active use and Castelli's decision to run the zip off-center is a genuinely smart engineering call that eliminates the zipper-on-zipper bulk problem at the chest. Paired with a Flanders or Prosecco base layer underneath and a quality jacket on top, this builds one of the most effective cold-weather systems I have used on the bike."

The Cold Days 2nd Baselayer from Castelli exists because base layers have a ceiling, and on the coldest rides that ceiling is not high enough. Designed explicitly to sit between a base layer and an outer jacket, it uses Polartec Alpha fabric to deliver maximum insulation and moisture management in a 176-gram package that does not compromise the fit of anything layered over it.

The off-center half zip is a considered engineering decision, positioning the zipper away from the center chest to eliminate the stacking bulk that occurs when multiple garment zippers align. The fit stays close enough to tuck into tights but relaxed enough at the hem to wear out, giving riders flexibility depending on conditions and preference. Castelli specifically developed this piece to pair with their Prosecco base layer underneath, though it integrates cleanly with any close-fitting base layer in the right temperature range.

For riders building a layering system for rides in the 17 to 41 degree Fahrenheit range, the Cold Days 2nd Baselayer is the component that makes the whole system functional at the extreme low end of that window. It works in combination with a Flanders, Medio, Merino, or Seamless base layer underneath and any Castelli winter jacket on top.