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Castelli Iride Seamless Long Sleeve Top

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Item # CST0669

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Item # CST0669


The foundation of any winter wardrobe, a base layer keeps your core warm by wicking moisture away from your skin. Thanks to new state-of-the art seamless knitting technology and a moisture-wicking blend of polypropylene, nylon, and lycra, the Castelli Iride Seamless Long Sleeve Base Layer is the company’s softest and most comfortable base layer to date.

Polypropylene is a popular choice for performance base layers as the fabric’s fibers quickly transport moisture away from your skin. Once the moisture has reached this point, the Iride’s nylon layer takes over, transferring the moisture outward to the surface of the garment to evaporate there, keeping you warm and dry. The Iride is also cut long at the waist to keep the base layer from riding up and out of your bibs.

The Castelli Iride Seamless Long Sleeve Base Layer is available in Black and comes in three sizes -- Small/Medium, Large/X-Large, and XX-Large. Like most Castelli clothing, the Iride base layer is designed to be form-fitting as the technical fabrics used to construct the garment work best when in close contact with your body. Be sure to check the sizing chart to ensure proper fit.

  • Polypropylene fibers transport moisture away from the skin to your outer garment
  • Seamless knitting technology prevents irritation

Tech Specs

polypropylene, nylon, lycra
Insulation Weight:
Recommended Use:
layering, cycling in cool weather
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...


Just as folks say, very tight.

  • Familiarity:I've used it several times

I normally wear a large or sometimes medium in standard clothing so thought a L/XL would fit. I have worn it several times and it works GREAT to keep me warm but is plain uncomfortably tight. Worn in temps to mid 30's with jersey and standard warm riding jacket and kept warm. I just wish it was a bit larger.


too tight

  • Familiarity:I returned this product before using it

no longer a young buck and as middle age and 5'8" and 160 lbs i knew that it was going to be snug but the s/m was just too tight for me and had to send it back. i have been used to craft or merino wool baselayers and so will probably stick to them for winter riding.

Avg. ride time: 1h 19m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Love it .. mostly.

  • Familiarity:I've put it through the wringer

Great product. I prefer it to my Assos 6/7 Winter layer (it is lighter, thinner, more wind stop ..... less breathable)... This product is really tight but constructed to stretch and bend where needed. I have the white version in long sleeve and black in short sleeve. It stains where sweat forms like the bib lines, arm pits etc etc. so I would pay more for the black ... the white is always on sale :) If I wear this with a Gabba product I am perfect at 3-10 C ish. With a Castelli winter coat product I am comfortable from -5 - +5 and cursing myself above :)

Avg. ride time: 4h 59m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Great base layer for a wide temp range

  • Familiarity:I've put it through the wringer

Solid base layer. I got the S/M size. I'm 5'8" and just under 140 so pretty slim. The base layer is definitely skin tight on me but it still allows for good range of motion. It also keeps me very warm since it's such a snug fit. I've used it in temps as low as 15-20 degrees with a jersey on top and a winter jacket and it's been perfect. Then I'll wear it with a lightweight windproof long sleeve jersey in temps 35 and up and it's perfect. Very versatile piece of kit!


Good base layer.

    Very nice, but pricey at full price. Use it under a long sleeve Gabba rain jersey. Not sure it cools or warms any better than other Castelli base layers at half the price. Very comfortable and form fitting.

    Avg. ride time: 1h 25m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Awesome Base Layer

    • Gender:Male
    • Familiarity:I've used it several times

    Worth every penny.

    Avg. ride time: 0m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Did Castelli drop the thumb loops from...

    Did Castelli drop the thumb loops from this shirt? The catalog still still includes them in the specs, but the shirt I recently ordered did not have them.

    Best Answer

    I just checked the Castelli site,(they're showing this base as still having the thumb loops).

    Maybe contact Castelli...see why, if they disc. this feature, they are still showing it on their site as having the thumb loops!

    (if I have time, I'll look further into it for you...)

    I have this base layer and it does not come with the thumb loops. It's very form fitting so I don't have any problems with the sleeves riding up and personally I prefer no thumb loops with my tops as they tend to create pressure points from rubbing under my gloves. I wear it under a long sleeve jersey when it's in the 40s and under a winter jacket below 40F and it really wicks well so I stay mostly dry and warm. I normally wear a women's medium in Castelli and the men's small/medium is a bit loose but not enough to chafe or bunch up under my kit. Hope this helps.


    Gold, I tell you. GOLD.

      Firstly let me say I'm fussy. And I don't mind spending money on something that works. But it better work.

      Castelli never let's me down. I love this brand.

      This garment (I bought 2 this season to add to the 2 I bought 2 years ago) is excellent. It's surprisingly warm. As MSA1288 said, I wear it under a thermal jacket and I'm good to go for a frosty morning. I wear it running and cycling.

      I am castelli buyer now. They just make good stuff. Buy a size bigger than you normally do - and it'll fit like you always dreamed of - maybe even better.

      I have these and the castelli long thermal bib knicks, short bib knicks and the short knicks. Man I just love their clothes. Now I don't mind winter at all. The clothes made me enjoy it.


      Works like a good baselayer should

        I purchased this three weeks ago just in time for nasty weather two consecutive weeks in a row. This works great under a thermal jacket or any jacket, and even under loosely fitted jerseys. It kept me warm on chilly days (40F to 55F) and wicks moisture like no other. As for the fit, I am 5'5", 160lbs with a 30" waist and a 38" chest, I got the small/medium size. Yes it is tight, but not uncomfortable, it's made to hug the body especially in the riding position. If it fits too loosley it will not provide you any warmth on those cold rides and its moisture wicking capability will go down.



          runs real small. i got an xxl. ok for underneath layer. im 5-11 and 175 athletic somewhat muscular build. wanted to use it as a 2nd layer. if ur a 150 lb. rider it will problay work but.....3 star for size alone , otherwise ok