Castelli Core Seamless Long Sleeve Base Layer (Black)

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Price: $79.99

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Castelli Core Seamless Long Sleeve Base Layer is seamless for comfort and surprisingly warm for its weight, this base layer is ideal in cool conditions, providing excellent moisture management.  Time to give seamless base layers another try. Seamless construction promises stretch and comfort, but most base layers on the market have a nylon and Lycra mix that feels comfortable when you put it on but then ends up feeling wet when you're actually riding, and you freeze when you stop. Castelli worked hard to make this Core Seamless base layer keep you warm and dry, thanks to the addition of polypropylene and polyester yarns, while not compromising the stretch comfort of seamless. 


  • 84% polyester / 16% polypropylene yarns provide soft, warm wicking and exceptional stretch fit
  • Seamless construction means extra comfort
  • Lighter weight on side and back
  • Wide neck opening to fit under short-collared jerseys

Gender: -
Fabric: Polyester & Polypropylene Yarn
Sleeve Length: Long Sleeve
Color: Black

This product was added to our catalog on October 9, 2020

George Ridgley
Tuesday, Nov 23 2021 (about 2 years ago)
Castelli Core Seamless Long Sleeve Base Layer (Black) (S/M)
Not overly impressed. The package says it is good down to 39 degrees and that is probably pushing it unless you have multiple heavy layers on top of it. It definelty seems light weight. The fit is very tight which I guess is on purpose. I normally wear medium and purchased L/XL. It is skin tight.
Satisfied Buyer
Verified Owner
Tuesday, Feb 9 2021 (about 3 years ago)
Castelli Core Seamless Long Sleeve Base Layer (Black) (S/M)
Good, thick base layer.
Have worn in temps as low as ten degrees with two additional top layers and stayed comfortable.
Seems to stay dry as well when temps increase some and you get a fair sweat on a cold day.

Castelli Sizing: Many Castelli products are designed with a European race-fit. It is not uncommon to size up one size for a standard, race fit or two sizes for a more relaxed fit.

Measurement Guide:

  1. Chest: Measure the circumference around the fullest part of chest, under arms
  2. Waist: Measure circumference around natural waistline keeping the tape a bit loose

Circumference (in)
Circumference (in)

Note: All measurements are provided by the manufacturer and may vary depending on how measurements are acquired. Castelli instructs that for best results measurements be taken over underwear. Castelli recommends sizing up if measurements fall between sizes for a better fit.