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Castelli Idro Jacket - Men's

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5 Reviews


The best and lightest.

Over the past five years, Castelli has made a name for itself by continuously redefining what we expect from race-worthy, breathable weather protection. The Gabba, the Tempesta, the Perfetto—these names have come to define the genre. The Idro Men's Jacket is this heritage's latest addition; it's also possibly the most impressive. It's the result of a partnership with W.L. Gore and Associates, and—with Castelli proudly proclaiming it the lightest Gore-Tex jacket in the world—the Idro combines the best and lightest features from across the Italian brand's line.

The jacket's key construction element is Shakedry, a breathable membrane that enjoys the water- and windproof qualities that made Gore-Tex a legend in the general outdoor industry. It'll block the wind like your Gabba, but it's also literally waterproof, so heavy, prolonged rain that exposes the Gabba as merely water-repellent doesn't penetrate the Idro. This is backed up by the "GUARANTEED TO KEEP YOU DRY" policy, a promise that Gore-Tex rolls out in CapsLock for its official literature.

Considering the enormity of that statement, we've opted to preserve Gore-Tex's jarring textual choice in our own copy—especially since the Idro pairs that huge claim with a correspondingly tiny one: it only weighs a claimed 123g for a size large. This low weight is possible because Shakedry eliminates the usual face fabric, so it's a two-layer membrane that preserves an uncompromising balance of breathability and protection while reducing bulk to expand Gore-tex's appeal to include elite cyclists.

Castelli's penchant for very targeted innovation means that navigating its catalogue can occasionally be as tricky as negotiating damp corners on rainy descents. For comparison's sake, we'd situate the Idro as an ideal blend of two of Castelli's leading anti-weather tops: the Riparo Rain Jacket and the Tempesta Race Jacket.

The Riparo is a few grams lighter than the Idro, but it's also far less breathable. Castelli's Tempesta Race Jacket, on the other hand, is as breathable as the Idro, but it's also almost 80g heavier—that's almost 70% more weight. If this jacket were intended for nothing but leisurely noodles, then we'd have no problem with those added grams or the risk of internal moisture accumulation during hard efforts. But it's not for leisure; it's for racing. It's for days when you can't afford to let Mother Nature's springtime tantrums keep you from the start line, impede intervals, or force you to load down your bikepacking panniers with yet more heavyweight gear.

That stowability is arguably even more desirable for race situations than bikepacking, though. The Idro's ability to pack down to less volume than a pair of knit gloves (about half a pocket by Castelli's estimate) means it will actually stow in the minimalist pockets on race jerseys—a claim that neither the Tempesta nor the Riparo can make.

While it's not being stowed in those pockets, the Idro features zippered access to them, ensuring protection doesn't mean you're bereft of ride essentials. The front zipper is a waterproof YKK Vislon model, and it works with the anatomically shaped wrists and seam taping to ensure there are no coverage gaps or points of watery ingress to compromise the jacket's CapsLock guarantee. The seam taping is also reflective, which is another small detail that will help ensure your ride goes according to plan.

  • A cycling jacket for rainy, windy racing and training
  • Gore-Tex Shakedry membrane protects and breathes
  • Water- and windproof protection in a race fit
  • Full-length waterproof front zipper and taped seams
  • Minimalist bulk packs down to half-pocket size
  • Zippered access for jersey pockets underneath
  • Reflective elements to help maintain visibility
  • Castelli's latest effort to redefine inclement weather gear
  • Item #CST00GZ

Tech Specs

[membrane/laminate] Gore-Tex Shakedry (100% polytetrafluoroethylene)
Windproof Rating
<1 cfm
Claimed Weight
[size large] 123g
Recommended Use
Manufacturer Warranty
1 year

Tech Specs

  • Reviews
  • Q & A

What do you think about this product?

Have questions about this product?

Crazy Good So Far

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: XXL
  • Height: 6'1"
  • Weight: 182lbs

This thing is crazy light, sheds water like a duck, and does indeed shake dry.

I have worn it riding in a light drizzle, in 46F and windy, and in the shower. (Yeah, I wanted to see just how waterproof it is). It passed all three tests. In particular I think this would be a good emergency wind, cold or rain garment; on the forty-six degree day it was windy (14 mph) and wet: I wore a Craft long base layer, short-sleeved jersey and the Idro-- and it was plenty. The Idro is easily packable into a jersey pocket.

A nice touch is the zippered slash rear access in just the right spot to reach your jersey's right rear and center pockets; it also can be opened to allow a little through-flow of air to prevent ballooning if you unzip part-way in front.

A word on sizing. I'm 6'1" 182 and were I thirty years younger than my sixty I would be fretting about not being closer to the 175 that I weighed, well, thirty years ago. As it is, for Castelli race-cut jerseys I tend to fall somewhere between Large and XL so I bought this in XXL so as to be able to layer freely. The XXL on me accommodated a winter long-sleeved base layer and jersey fairly easily with a little bit of flapping but not much.

Damn Brilliant Jacket

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: XXL
  • Height: 5'11"
  • Weight: 195lbs

The Idro jacket definitely fit the bill for me in many ways. I didn’t get to wear it in a steady rain, so the jury is still out on it being waterproof. It is amazingly lightweight, warm in chilly conditions and *extremely* packable to a size to readily fit in a jersey back pocket.

When cruising along at 18+ mph, you will get wet from sweat while wearing the Idro. I guess there just isn’t a perfect trifecta cycling jacket of waterproof, packable and completely breathable. At least not at pace or over 30 minutes riding.

The jacket’s sizing is definitely small. I am 5’, 11” and 195. I usually wear a size large or XL. I ordered the XXL and was very pleased with its fit.

Cream of the crop

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: True to size
  • Size Bought: Large
  • Height: 5'10"
  • Weight: 160lbs

Remarkable jacket, well done Castelli! The size Large fits me perfectly. Ideal lightweight piece for the racer looking to fight the wind and rain. The Idro is cut for the aero position on the bike as it wraps nicely around your arms and core creating a slim fit from top to bottom with no excess material to bunch up. The cufflinks at the wrist and banding at the waist are snug and thin preventing outside elements in with just enough stretch. At 123 grams for a large, it is feather weight that will easily pack up into a small race jersey pocket. For how much protection you get, there won’t be many jackets this lightweight that pack down this small. Gore-Tex shake dry is a unique fabric that combines windproofness, waterproofness, and lightweight. Shake dry protects AND allows breathability to help with overheating, a combination hard to come by. The zip pocket on the right side is angled ergonomically making access easier than reaching all the way around for a center pocket on your back.

Nothing bad to say about this jacket. The slimness and ShakeDry technology make you feel like a superhero and help you perform like one too. The Idro has the protective qualities of the Tempesta and the Riparo but is also breathable and lighter weight coming in at 123 grams in a Large. For someone looking for a jacket to monitor a wide range of body temperature changes from interval training/racing in the wind and rain, invest in this. You will not be let down.

Feel free to contact with any questions!
Michael Walker - Customer Account Manager

Best Rain Jacket. Ever.

  • Familiarity: I've put it through the wringer
  • Fit: Runs small
  • Size Bought: XL
  • Height: 6'0"
  • Weight: 170lbs

I've owned more rain jackets than I reasonably should own, but I've been in search of the breathable yet waterproof jacket. I think I've found it. Better than my assos versions, better than my CAPO or Giordana, this jacket is great. I recently embarked on a 3 week riding trip and the first 14 days had rain of some sort. This jacket breathes quite well and is definitely waterproof. It's light, easy to pack, and has a great zipper. Why a great zipper? It's big and chunky, making it incredibly easy to zip while riding. The jacket runs a bit small, I purchased an XL, and I'm right around 6' tall and ~170 lbs. This one is highly recommended.

Superb !

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

This jacket is very impressive. It is cut close and trim for road cycling, which eliminates any flapping. It packs down to the about the size of a standard PBJ sandwich, smaller than a typical SS jersey. It’s extremely lightweight. It functions quite well as a cool-weather wind jacket at road speeds with added wind speeds ranging up to 30 mph (net pushing 50 mph). And in steady light rains it has proven completely waterproof, no breakthrough anywhere, for rides lasting up to ~ 2 hours. The single zippered vent on the right-side back allows you to reach your rear jersey pockets, and extends the comfort range on the high side by allowing for some reasonable ventilation. What makes it even more impressive is it works so well without the typical sweatbox overheating I associate with Gore-Tex jackets. This thing actually breathes, while being as waterproof as any jacket I have ever owned. Finally!

The comfort range depends on air temp, winds, and sun exposure. As a wind jacket on clear, sunny days, it remains comfortable and dry inside with a fall/spring short sleeve base layer (Assos 2.4) and short-sleeve summer jersey (Assos Mangusta) in the range of ~ 50 to ~ 60 °F. In gray, overcast, foggy conditions with steady light rain, moderate winds (6 mph) I’ve found it comfortable and dry with the LS version base layer and same jersey up to ~ 68 °F. I’ve not yet pushed it beyond those ranges on either the high or low side.

The fit is trim, without any excess fabric to flap in the breeze. It’s cut for road cycling in a fairly aggressive position. The size chart worked perfectly for me. All-in all, a superb piece of gear.

Hi CC, I am 6ft 2" with a 40" chest and 35.5" waist. Not sure if I am a Large or XL in the idro, any guidance would be appreciated!

Hi Beth, based on both fit characteristic of Castelli and your dimensions, I would recommend an XL. Also, given that this an outerwear item that may be worn with more than just a summer weight jersey underneath and possibly worn with a base layer paired with a winter long sleeve jersey may make the Large size a bit restrictive.

Feel free to hit me up directly for more information and I would be happy to answer any questions for you.

John McKone- Competitive Cyclist Sales Solutions