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Castelli Mezza Wool 9 Socks

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Item # CST0678

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Item # CST0678


Have you ever set out on a chilly morning only to have temperatures rise by the middle of your ride? Thanks to the use of a lightweight 100% merino wool, Castelli Mezza Wool 9 Socks are perfect for those “in-between” rides.

The Mezza 9 socks are designed to be as thin as summer socks (so they fit into your shoes easily), but they're made with lightweight merino wool so as to provide superior warmth and breathability. Such versatility makes these lightweight wool socks a terrific option for days when the weather doesn’t warrant a thicker, bulkier alternative.

Castelli Mezza Wool 9 Socks provide mid-length protection thanks to a nine centimeter cuff. They come in Black and White with a red vertical stripe up the back of the sock for a stylish, PRO-looking contrast. The socks come in three sizes -- Small/Medium, Large/X-Large, and XX-Large.

Tech Specs

100% lightweight merino wool
above ankle
Recommended Use:
cycling in fall weather
Manufacturer Warranty:
30 days

Size chart

Fuji Bicycles


Geometry Chart


Altamira LTD

Seat Tube


Effective Top Tube








Head Tube


Head Tube Angle


Seat Tube Angle


Bottom Bracket Drop


Chainstay Length



44 44.0cm 51.5cm


36.3cm 72.1cm


72.0 deg 75.0 deg 6.9cm 40.5cm 97.1cm
47 47.0cm 53.0cm


37.0cm 74.1cm 13.0cm 72.5 deg 74.5 deg 6.9cm 40.5cm 97.7cm
50 50.0cm 54.5cm 54.0cm 37.0cm 76.0cm 14.0cm 73.0 deg 73.5 deg 6.9cm 40.5cm 97.6cm
53 53.0cm 56.0cm 56.0cm 37.9cm 78.3cm 16.0cm 73.5 deg 73.5 deg 6.9cm 40.5cm 98.6cm
55 55.0cm 57.5cm 58.0cm 38.9cm 80.1cm 18.0cm 73.5 deg 73.5 deg 6.9cm 40.5cm 100.1cm
58 58.0cm 59.0cm 60.1cm 39.7cm 82.1cm 20.0cm 74.0 deg 73.5 deg 6.9cm 40.5cm


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Here's what others have to say...

Avg. ride time: 4m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

One of my favorite socks

  • Familiarity:I've put it through the wringer

I wear these all the time.. XXL for a size 10 US fits great. Really comfortable for any season besides summer. They are a lightweight sock so you dont sweat alot but dont expect these to keep your feet warm with any shoe covers in low temps.


Frosty toes...

  • Familiarity:I've used it several times

Great sock, good fit, is not a full winter sock. It may be merino wool, but it's not thick enough for temps 35-40 and breezy. Craft felt socks are the way to go. The Castelli will work for early Fall and Spring.


Absolute perfection

  • Familiarity:I've put it through the wringer

These Castelli wool socks are a work of art. Very high quality. Made in Italy. And 9 cm is the -perfect- height.

These Mezza socks feature superfine merino wool that is thin and very breathable. These socks will keep your feet cool and dry, and thus more comfortable; and no odor, naturally. Wool is a super fabric!

I wear these socks on all rides from 45/50* to about 75*. These are very versatile socks. (In really cold, sub 45* weather, I wear Castelli's medium-thick Quindici wool socks).

Sizing: I wear a 45.5 shoe in Sidi (10.5-11.0 USA). I bought a pair of these socks in both L/XL and XXL. The XXL fit much better (especially after washing). If you wear a 45+ shoe, definitely buy the XXL.


Great Socks!

    Awesome socks- Warm, comfy, and did the job. Rob the mountains of Carolina in 50 degree temps.


    Warm Merino Socks

    • Familiarity:I've put it through the wringer

    Been riding with toe covers in the low 40's and these keep my feet warm and dry. Surprisingly warm for such thin material and are of good quality construction.


    Great socks.

      Love these socks! Great for 40-70' weather. I wore it today on a ride that started out at 50' and climbed to 80' by the end. They breathe great and I did not feel (or think about) my feet getting overheated by the end at all. These socks fit well too without any bulkiness feel.


      ...VERY nice socks

        these are VERY nice quality socks. The 9cm cuff is just right, the wool is the real deal, these are thin enough not to be bulky under your road shoes, comfort +++