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Assos Mille GT Ultraz Winter Jacket



Expensive, but worth it if you ride throughout the winter

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Assos Mille GT Ultraz Winter Jacket offers fabulous cold weather performance, requiring very little to be worn underneath, with the inner being exceptionally soft. For me, the attached snood is more hinder than help, but overall this is an excellent bit of kit.

  • Pros: Fabulous insulation, sublime fit, supersoft inner fabric, brilliant temperature regulation
  • Cons: Neck protector can be a little annoying when unworn

The Mille GT Ultraz has been designed to let you tackle the worst that winter can throw at you, but at a more affordable price point than Assos' Bonka jacket. When I say affordable, this is still £260 (the Bonka is £370!). If you've not got that kind of cash, there are plenty of great alternatives at a much lower price, but if you can afford the Mille GT Ultraz then I'd say it's worth every penny.

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Money aside, let's get into how this jacket has been made. Assos uses a lot of different fabrics and it uses them really well. The thought that has gone into this jacket is brilliant.

Assos Mille GT winter Jacket Ultra AZ - riding.jpg

'Neos Light', a tri-layer softshell, is used on the frontal panel and upper back where most of the rain will fall. This fabric is waterproof to over 10m and although I still took a waterproof, I didn't find myself needing it much. The jacket will see off everything up to persistent heavy rain.

Assos Mille GT winter Jacket Ultra AZ - back.jpg

The sleeves feature two different materials, with the front section which catches the wind and rain being made from Neos Ultra. This is a slightly thinner dual layer that gets the waterproofing of the Neos Light with more breathability. On the underside of the arms is a lighter outer fabric as this area doesn't face the wind or rain.

Assos Mille GT winter Jacket Ultra AZ - sleeve detail.jpg

Internally, the jacket is lined with a super-soft brushed fabric called RX. It is one if the best things about the jacket and left me not wanting to bother with a baselayer. The only break in this fabric is a panel that runs up the spine. This is lighter and meant to aid temperature regulation.

Assos Mille GT winter Jacket Ultra AZ - buff detail 3.jpg

For a winter jacket, the collar is relatively low but the integrated neck protecter does a perfect job of stopping any unwanted chills. This contoured snood is made of the same soft RX fabric as the inner. That, along with the ergonomic design, makes it incredibly comfortable to wear.

Assos Mille GT winter Jacket Ultra AZ - collar.jpg

My only minor issue with the whole jacket is that when you don't want to use the snood, storing it in the elastic holder leaves a slightly annoying lump at the top of your back. That said, if you're heading out in this jacket, it's probably cold enough that you'll be wearing the snood anyway.

Assos Mille GT winter Jacket Ultra AZ - buff detail.jpg

One of the more interesting features is the 'triple-ramp concept pockets'. Essentially, you've got your three standard, well-sized pockets but with the addition of a closure flap that tucks over things like your phone for increased security. They're easy to get into while riding, but they should stop things flying out should you need to pop a bunny hop.

Assos Mille GT winter Jacket Ultra AZ - pockets.jpg

Out on the bike and my first ride took the form of a steady group ride on a fresh 4°C morning. The jacket, combined with a baselayer and lightweight jersey, was right at home. The unrestrictive yet close fit meant I was comfortable sitting both on the bike and in the cafe. At the shoulders, the shape is great and this medium measures well against the sizing of other jackets I've tested.

Assos Mille GT winter Jacket Ultra AZ - shoulders.jpg

The high breathability left me feeling snug, not sweaty, despite four hours of zone 2 (steady riding but still able to converse, basically).

> Buyer's Guide: 14 of the best winter cycling jackets

The rear drops down to cover the lower back while the front hem is raised to avoid too much bunching. The sleeves are a good length and work well with mid-high cuffed gloves. It's just a really comfortable jacket to wear on long, cold rides.

Assos Mille GT winter Jacket Ultra AZ - hem.jpg

The attention to detail is what you'd expect from a premium brand. A large toggle has texture dots on the back to aid grip while wearing big gloves. The full length zipper is smooth and easy to operate on the move, and a large flap of windproof material sits behind it, stopping irritation and also any draughts.

Assos Mille GT winter Jacket Ultra AZ - zip detail.jpg

In terms of value, it is certainly a premium product and not one that I could personally afford. If you do have the money, you'll be very pleased with the performance and attention to detail. It's also slightly cheaper than Castelli's Alpha RoS Jacket (£275), probably its closest rival that we've tested. Both would be brilliant options; there are a few more colour choices with the Alpha, with the Mille GT Ultraz focusing more around black.


Expensive, but worth it if you ride throughout the winter test report

Make and model: Assos Mille GT Ultraz Winter Jacket

Size tested: Medium

Tell us what the jacket is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

From Assos: "An elevated take on our much-acclaimed and iconic Bonka jacket, the all-new membrane on this ULTRA winter jacket serves up the ultimate equipment for riding in the most frigid conditions. We've gone to extremes in conjuring superlative insulation, climate control and detailing in this meticulously engineered winter jacket, which we've ensured will hit winter out of the park"

Tell us some more about the technical aspects of the jacket?

From Assos:

NEOS LIGHT: Our in-house developed tri-layer lightweight soft-shell constructed with a bonded PU membrane. Water-repellent and close fitting, this tech-savvy textile is waterproof to >10 m and highly breathable. Used in twinDeck on the frontal panel and upper back/carré. Waterproof >10 MT. High breathability MVP 27.000 gr/m2/24h JIS L 1099 B-1:2006.

NEOS ULTRA in twinDeck with RX: Our proprietary ultra-thin dual-layer soft-shell, constructed with a bonded PU membrane is used on the upper sleeves. Water-repellent, close-fitting and highly breathable. Waterproof >10 MT. High breathability MVP 44.500 gr/m2/24h JIS L 1099 B-1:2006.

RX: In two weights, deployed strategically as a lining and as the dorsal panel. A brushed bi-stretch warp knit fabric with wicking and thermoregulation performance.

Integrated neck protection: The latest evolution of our lauded neck protector created using our thermal RX soft-shell. Now more ergonomic than ever, the neck protector can be subtly stowed in the elastic holder when not needed or pulled out for crucial moments to provided added warmth.

'Triple ramp' concept pockets: Using all of our riding experiences we have created our new pocket design with the optimal height for ease of access. Thoroughly tested pocket design with a new, game-changing layout that ensures your contents are secure and stable regardless of your exertion. Internal seams fashion a barely there closure to keep your wares in check. For this winter jacket these now feature longer reflective stripes for enhanced visibility.

Rear stabilizer S7 knit: A mono-stretch material with minimal give in the vertical axis. The ASSOS rear stabilizer panel design allows for stable, high capacity pockets that won't sag.

2W waistWave construction: For a cleaner look and more ergonomic edges in our Sens Bicolor textile.

Raglan cut: Comfort-led sleeve design with a raglan cut for easy, free movement and reduced drag.

Full-length camLock zip: Slim, lightweight zip for individually adjusting to the conditions.

Rate the jacket for quality of construction:

It's quickly apparent that Assos has considered each panel's design and then put the jacket together very well. The stitching is very good and nothing feels like it has changed from new.

Rate the jacket for performance:

After a hot summer, I'd forgotten just how cold it can get on a bike. This has become my go-to jacket for anything below 10°C and it doesn't feel heavy, restrictive or sweaty when riding. Put simply, this jacket performs perfectly.

Rate the jacket for durability:

So far, I've taken this out seven times and washed it after six of those rides. The waterproof coating is still going strong and the inner fabric is still perfectly soft.

Rate the jacket for waterproofing based on the manufacturer's rating:

This isn't a full-on waterproof, but it has seen me able to leave my rain jacket in my pocket until the heaviest stuff starts. Assos rates it to 10m but in practise, it defends you against wheel spray, light rain and a strong shower.

Rate the jacket for breathability based on the manufacturer's rating:

This breathes really well for a multi-layer winter jacket. You can tap along in zone 2 without getting soaked in sweat.

Rate the jacket for fit:

Everything feels like it's spot on. The back isn't dropped too much but it still protects well. The sleeves finish perfectly on the wrist and the collar is snug on the neck but not restrictive.

Rate the jacket for sizing:

Sizing I would say is very good indeed. My medium wasn't tight but it also wasn't too loose. You'll easily get more layers on underneath and a rain jacket fits over the top.

Rate the jacket for weight:

It's a solid winter jacket.

Rate the jacket for comfort:

Flawless. It allows you to move freely, doesn't feel bulky and it fits perfectly on and off the bike.

Rate the jacket for value:

It ain't cheap… but it is £15 less than Castelli's Alpha. If you've got this kind of cash then you'll be getting a great product for your money. That sounds like good value to me.

How easy is the jacket to care for? How did it respond to being washed?

You're going to want to look after this... wash it at 30°C then hang it up to dry. But that's pretty much all cycling kit these days.

Tell us how the jacket performed overall when used for its designed purpose

It really was excellent in the cold weather. I only really got sweaty when I decided to do some climbing intervals. When rolling around the flatlands at zone 2 (basically, riding steady but able to chat), there's no overheating.

Tell us what you particularly liked about the jacket

The comfort you get is brilliant. The inner fabric is so soft and the fit means you're never restricted, on or off the bike.

Tell us what you particularly disliked about the jacket

I'd rather have the snood as a separate item.

How does the price compare to that of similar products in the market including ones recently tested on

I'd say that its direct rival is Castelli's Alpha jacket. They both promise the same performance and they both deliver.

Did you enjoy using the jacket? Loved every second. It's genuinely a pleasure to wear.

Would you consider buying the jacket? Love to, but I just don't have this kind of disposable cash.

Would you recommend the jacket to a friend? Yes. Provided that they've got deep pockets.

Use this box to explain your overall score

Absolutely fabulous to wear and performs exceptionally on its own or as part of a layering system. The breathability is great and the temperature range is anything below 10°C. The snood annoyed me a little bit as I'm used to being able to choose when I wear one, and stowing it down your back isn't the best solution. Other than that, though, and a price that some will find hard to swallow, it's a brilliant bit of kit that will last for years.

Overall rating: 9/10

About the tester

Age: 24  Height: 177cm  Weight: 62kg

I usually ride: Cannondale Supersix Di2  My best bike is:

I've been riding for: 5-10 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, club rides, general fitness riding, I specialise in the Cafe Ride!

Add new comment


arichman | 4 years ago
1 like

Probably the most important thing to know about this jacket is that the fit is intended to be extremely close. If you don't know that, you'll probably think you got the size wrong.  This is largely the fault of Assos, which calls this a Mille jacket, which is supposed to mean their relaxed 'comfort' fit. It fits nothing like the Mille Bonka jacket which came before, but in fact fits very similarly to that of the Cento Bonka, which was a jacket specifically made for race snakes. I'm a Small according to Assos' chart, 36" chest and 5' 8", and it fits me very well but it is no way a relaxed fit. There is room for one layer, no more. I'm sure that's what Assos intended, Assos wants you aero even in winter. I'd say if you don't want that fit, look elsewhere. If you size up, the sleeves and the zipper will be too long, which personally I can't stand...

markovich | 4 years ago

Its considerably heavier in build and protection. The standard winter version is great I'd say down to 6 degrees. Below that I'd opt for the Ultraz

TonbridgeJon | 5 years ago

How does this differ from the Mille GT winter jacket (the not 'Ultraz') version?

rtw replied to TonbridgeJon | 5 years ago
1 like
TonbridgeJon wrote:

How does this differ from the Mille GT winter jacket (the not 'Ultraz') version?


Greater insoluation than the Mille GT winter jacket - which is also warm, but not as warm as the Ultraz (which is a 'frost on the ground' jacket in my opinion).

Chris Hayes | 5 years ago

I'll get one when my Assos Prosline Airblocks die...they're about 20 years old and still going strong, however...and I have two!   If the above is as well made it'll be a solid investment. 

Chris Hayes | 5 years ago

I'll get one when my Assos Prosline Airblocks die...they're about 20 years old and still going strong, however...and I have two!   If the above is as well made it'll be a solid investment. 

ashfanman | 5 years ago

Not really sure I understand how this fits with the Bonka. How does that justify being so much more expensive? Or is this ultimately desinged as a replacement?

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