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Castelli Thermolite 9 Socks

$10.17 $16.95 40% off

Item # CST003H

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  • Select options
  • Black, S/M ($10.17)
  • Black, XXL ($10.17)
  • Black, L/XL ($10.17)
  • White, XXL ($10.17)
  • White, S/M ($10.17)
  • White, L/XL ($10.17)
  • 100% Guaranteed Returns

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    on orders over $50
Item # CST003H


Lite, but still Thermo.

We're big fans of Castelli's Thermolite 9 socks for a few reasons. First, they're fantastic, durable, comfortable cycling socks. Second, their name tells their whole story. They're thermally insulated socks, but only mildly so, excellent for cool-weather riding conditions, and not so insulating as to be uncomfortably warm when the sun comes out or when the pace cranks up. Thermolite is a medium-density, hollow-core polyester material that promotes breathability and moisture transfer to preserve the comfort of your feet, while still insulating them enough to fend off the chill of fall days. The midfoot is supported by an anatomic band of fabric that prevents cramping and hotspots. The socks have a nine-centimeter cuff, come in the sizes S/M, L/XL, and XXL, and in the colors Black or White.

Tech Specs

Thermolite polyester
9 cm
Recommended Use:
cool weather cycling
Manufacturer Warranty:
30 days

Size chart



Castelli Socks
US Men's shoe
4-7 8-10 11-14
US Women's shoe
5-7 8-10 11-12
How to Measure:
For best results, take measurements over your underwear.

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Here's what others have to say...

5 5

Best winter sock

  • Familiarity: I've put it through the wringer

Absolutely love these socks. Not overly bulky like wool socks, but keep the feet nice and warm. Also very durable. Had several merino wool socks that have quickly developed holes, these have lasted all winter for me and there's no sign of any holes developing. Nothing bad to say about these socks.

5 5

Castelli never disappoints

What can I say, Castelli clothing never lets me down. These socks fit perfect and feel great.