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Castelli Flanders Warm Half-Zip Base Layer - Long Sleeve - Men's


Item # CST002X

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  • Grey, XS ($89.95)
  • Grey, M ($89.95)
  • Grey, L ($89.95)
  • Grey, XL ($89.95)
  • Grey, XXL ($89.95)
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Item # CST002X

Enjoy autumn from the saddle.

With the changing leaves and air as crisp as a new-crop apple, fall is one of the best times to ride a bike. But it can also be chilly, especially if your schedule doesn't always allow you to wait for the warmest part of the day. To address this, we turn to Castelli's Flanders Warm Half-Zip Base Layer. While we're not sure if the name means that it's as warm as Flanders (which… what?) or if it means that it's warm enough to wear while cycling in Flanders (more likely), we do know that it fends off cold like Museeuw fended off late-stage attacks in the race of the same name.

The Flanders Half-Zip is comparable to its non-zip sibling in every respect except for the zipper. It's made with the same durable SottoZero Fleece that insulates and wicks, and includes the same mesh inserts in the underarms. The flatlock stitching and flat hems mean the Half-Zip will fit as comfortably as the non-zip. Castelli recommends it for use in 23 to 46 degrees Fahrenheit, and, while this range may seem excessive, we find that the Flanders gets the job done in all conditions when layered with the right outer layer.

The Castelli Flanders Warm Base Layer - Men's is available in six sizes ranging from X-Small to XX-Large in the color Grey.

Tech Specs

SottoZero Fleece
Recommended Use:
cold-weather cycling
Manufacturer Warranty:
1 year

Size chart


Men's Apparel
Chest 36.2in
Waist 31.5in
Hip 37in
Inseam 31.9in
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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Avg. ride time: 5h 58m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Nice material. Don't like the zipper.

  • Familiarity: I returned this product before using it
  • Fit: Runs small
  • Size Bought: XXL

I ordered this base layer because it sounds like what I need for deep winter riding under my Giordana FormaRed Carbon jacket (which I love). I thought about the same base layer without a zipper but CC was out of it at the time, so I ordered this half zipper. The material feels great and "extra fluffy" while being thin which is what I am looking for but the zipper pokes at my neck which is a admittedly a 17 inch neck. I tried to unzip it a bit to make that go away and could tell it was not going to make me happy. Others with skinnier necks may feel completely different about it. I am returning this one and getting the non-zip one now that it is in. That is the only reason for two stars.

Keep the ride toasty

  • Familiarity: I've used it several times

This has warmth without the bulk, so even if you need to add a 2nd base layer your good depending on the temps! The half zip keeps the neck warm too along with a Castelli winter jacket and your set! The XL size fits me fine.I am 6'.0" 165lbs

soft and warm base layer

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

This is a great base layer for colder weather. I've layered it with a poly long sleeve jersey for 50* and thought it was a bit too warm. Which is a good thing. Lets me wear it in lower temps and be ok or as a base layer with my winter jacket. It is also super soft against the skin! Sizing was great - XL for me, as I'm 6'1", 195lbs.

Avg. ride time: 5h 42m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Castelli's inconsistent sizing

  • Familiarity: I've used it several times
  • Fit: True to size

Castelli makes some of the best cycling attire in the market. Almost all my cycling gears are Castelli. However, this Flanders Warm Half-Zip Base Layer (long sleeve) exposes yet again my frustration with Castelli's inconsistent sizing. Last year, i bought two XL Castelli Flanders Long Sleeve Base Layer (long sleeve). They were way too small so they had to be exchanged with the largest size available: XXL. I am 6'2" and weigh about 190 lbs. The XXL Flanders Long Sleeve Base Layer was a little too short on the sleeve and i could barely put my head through. It was with this understanding that i ordered an XXL Flanders Warm Half-Zip Base Layer (Long sleeve). Turned out, this is one size too big for me. An XL would've fitted me much better.

What i like about this base layer is the ability to unzip the top half of it if you are feeling a little too warm. The zip also helps when you are putting it on or taking it off.