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Castelli Thermolite 9 Socks

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Item # CST2487

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Item # CST2487


Warm feet are happy feet

If you're anything like us, your feet are the first to freeze on a frosty winter ride. However, with the right protection, this sensation can be a thing of the past. Of course, on particularly nasty days, a quality pair of covers are crucial, but you still need an intermediary base like the Castelli Thermolite 9 Socks to properly stave off the chills.

To achieve this level of warmth, Castelli constructed the socks from its namesake, the Thermolite fabric. Thermolite features a hollow-core polyester construction that insulates while pulling moisture away from the skin. Not only does this guarantee a dry riding experience, but the quick removal and evaporation of sweat provides a consistent level of warmth.

For the guts of the construction, Castelli used a flat-knit design to minimize the volume of the socks. Now, your socks will fit comfortably within your shoes, feeling light, airy, and warm for the whole ride.

The Castelli Thermolite 9 Socks are available in the colors Black and White and in sizes Small/medium, Large/x-large, and XX-Large.

Tech Specs

[sock] Thermolite
above ankle
Recommended Use:
winter road cycling
Manufacturer Warranty:
30 days

Size chart





US Men 3.5-7 7.5-9 10.5-13
EU Men 35-39 40-43 44-47
US Women 5-7.5 8.5-9.5  
EU Women 35-38 39-41  

Reviews & Community

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Here's what others have to say...

4 5

Warm, not as good with sweaty feet

  • Familiarity: I've put it through the wringer

These are warm when not under my Diluvio Shoe Covers. When I sweat under my Diluvio Shoe Covers, the Castelli Merino socks are better. I wear these in the 55F to 45F regime, with no shoe covers. Unlike the Merino socks, these do not shrink appreciably when washed.

I bought the L/XL for my Shimano size 43 foot, and they fit fine.

4 5

Silly me

  • Familiarity: I've used it several times

It may sound dumb but I thought they were 9 socks that came with it. ikr. well it's only a pair of great socks, keep your feet dry and they never pull down.

5 5

Warm Socks!

  • Gender: Male
  • Familiarity: I've put it through the wringer

I've worn these for most of the cyclocross season without shoe covers, and haven't suffered any cold toes yet! I also like these as hiking socks during the winter, as they are very warm and also not super thick. They wick sweat great so you don't have to worry about having soggy feet.

5 5

Great socks

Very comfortable warm sock, not too thick and very breathable! perfect option for cooler winter weather.

3 5

Good Socks

I like these socks, but I got them for winter riding and they do not stand up to the cold winter we are have here in Los Angeles. Early mornings are bitter 36-45 degrees.

Responded on

36-45F...bitter? Try coming up North (Great Lakes/Midwest, with that so-called 'Polar Vortex'), you'll see what bitter really is! Thanks for the review, anyway! Will look for another brand maybe.

5 5

Great Socks

I don't think socks need to be special, but these are pretty nice. Comfortable, warm enough when it's cold, stay nice and dry and look alright to wear.