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Castelli Flanders Wool Long Sleeve Base Layer

Sale $59.97 $99.95 40% off

Item # CST2705

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  • Black/ Grey Stitching, S ($59.97)
  • Black/ Grey Stitching, M ($59.97)
  • Black/ Grey Stitching, L ($59.97)
  • Black/ Grey Stitching, XL ($59.97)
  • Black/ Grey Stitching, XXL ($59.97)
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Item # CST2705

Who said being sheepish was a bad thing?

Before the advent of synthetic lycras and waffle-weaves, cyclists wore natural fibers such as wool and real chamois leather. And, although you may feel faster wearing all of the latest textiles, for some purposes, wool trumps them all. The Castelli Flanders Wool Long Sleeve Base Layer is a natural alternative to the latest synth craze.

The purpose of a base layer is twofold. First, it provides a comfortable barrier between your skin and outer layers, such as bib tights' straps or rain jackets, and second, it helps to regulate your core temperature. The latter is accomplished by pulling moisture away from the skin so that cold winter air does not create an evaporative cooling effect. Whereas other base layers rely upon combinations of fabrics to wick moisture, the 18 gauge merino wool, from which the Flanders base layer was constructed, does it all.

Merino wool is most known for its non-abrasive qualities, but the benefits don't stop there. Merino wool is what we call a "hydrophilic" fiber, meaning that it has the natural ability to positively interact with water. In fact, Merino is able to absorb as much as 30 percent of its weight before exuding the sensation of wetness. Truthfully, when was the last time you saw a soggy sheep? Because it is able to hold so much moisture, even though the cold air may slow evaporation, your skin will remain dry. When skin is dry, body heat is able to create a small barrier of warm air that acts as an insulating layer.

Additionally, merino wool is naturally antimicrobial. It is a base layer fabric of choice for multi-day adventurers because it does not hold odors. This property is furthered by Merino's natural ability to disperse electrostatic charges, which means your base layer will not pick up lint or dust.

In addition to a form-fit, the Flanders base layer features a high crewneck collar to keep cold from creeping down the front. There are few seams, but when necessary, Castelli uses flat lock stitching to minimize chafing. The back is slightly extended to stay tucked into your bib tights.

The Castelli Flanders Wool Long Sleeve Base Layer is available in sizes Small to XX-Large in the color

Tech Specs

merino wool (18-gauge)
form fit
Claimed Weight:
18 gauge
Recommended Use:
performance road, cyclocross
Manufacturer Warranty:
30 days

Size chart


Men's Apparel
 Small Medium Large X-Large 2X-Large 3X-Large
Chest  35.5 - 37in
(90.2 - 94.0cm)
37 - 38.5in
(94.0 - 97.8cm)
39 - 41in
(99.1 - 104.1cm)
41 - 43in
(104.1 - 109.2cm)
43 - 45in
(109.2 - 114.3cm)
45 - 47in
(114.3 - 119.4cm)
Waist 29.5 - 31.5in
(74.9 - 80.0cm)
31 - 33in
(78.7 - 83.8cm)
33 - 35.5in
(83.8 - 90.2cm)
35.5 - 37.5in
(90.2 - 95.3cm)
38.5 - 40.5in
(97.8 - 102.9cm)
41 - 43in
(104.1 - 109.2cm)
Hips 36.5 - 38.5in
(92.7 - 97.8cm)
38 - 40in
(96.5 - 101.6cm)
40 - 42in
(101.6 - 106.7cm)
42 - 44in
(106.7 - 111.8cm)
44 - 46in
(111.8 - 116.8cm)
46 - 48in
(116.8 - 121.9cm)
How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Measure around the fullest part of your body at the top of your legs.
Using pants that fit well, measure the crotch seam to the bottom of the leg.

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Here's what others have to say...


warm and looks good

  • Familiarity:I've used it several times

I had doubts about how warm this would be when first viewed, but it was soft against my skin {not scratchy] and combined with the Gore Phantom jacket i was comfortable at 32 degrees. This will be a favorite by itself or layered.


Wooly Bully

  • Familiarity:I've put it through the wringer

This piece is bossy. 6'1 180lbs... I like an XL for a hugging fit. It handles hot and cold with ease. I throw this underneath a thermal jersey or a jacket on colder days. i always gravitate to this above my other Flanders Warm and WS because of the way it breathes. The synthetics simply sponge and hold too much moisture. The Flanders Wool owns in temps from 30 to 55. Classy and comfortable design. I love this guy.

Wooly Bully

Are you wearing that under the Alpha Jacket? If so how do you find the 2 work together?

Like Peanut Butter & Jelly. They are perfect together. If things get toasty start to work down the ladder. The wool provides a less intense warming that allows you to ride hard in cold temps and not get too wet. For me, the wet/cold is the most uncomfortable. Unzipping the outer of the Alpha allows you to dry the base layer almost instantly. The wicking and drying of this base is truly top notch.



  • Familiarity:I've used it several times

Warm when it's cold. Cooler as it warms up. Comfortable up to about 60 or 65 degrees. Dries very fast and is still effective if slightly damp from mist, sweat, etc as only wool can be. Very comfortable - wore it all day on a cool double century. Keep them in a Ziploc bag... moths love them too! I own two for now.


great wool jersey

  • Familiarity:I've used it once or twice and have initial impressions

I love the feel of well-made wool. This has a great fit and feel! Nicely tailored. I expect to get many years of use from this jersey.


mine doesn't look like the picture

  • Familiarity:I've used it several times

my XXL has white stitching all over. not a real big deal, but the pic should be changed to reflect the actual product. also, the logo on the chest is way bigger.