Assos Mille GTS S11 bib shorts review: Hot weather standouts and very comfortable, but not without flaw

The Assos Mille GTS S11 bib shorts are the latest addition to the historic Swiss brand's comfort and endurance focussed Mille range. Whereas the Equipe line is focussed on racing, compression, and aerodynamics, the Mille kits put some of those more to the backseat. However, the Mille GTS S11 bib shorts do draw some inspiration from the Equipe line-up, implementing some lower level compression for comfort, while having enhanced breathability features. These are a pair of cycling shorts that excel in warmer environments, be that out in the sun or on the indoor trainer.

At £215, they are in the higher reaches of the cycling shorts price bracket, aimed more towards premium level and aimed squarely at being the best cycling shorts out there. However, their performance, with a heap of Assos proprietary fabrics and features, really do perform exceptionally well. The legendary Assos chamois continues to impress with greater breathability features added, plus the updated infamous KukuPenthouse is excellent. 

These are really competitors to the likes of the Rapha Brevet bibs, Q36.5 Dottore Pro, and Castelli Superleggera offerings which all fall into a similar price bracket with a focus on comfort and moisture wicking without sacrificing other performance elements. So how do the Assos Mille GTS S11 bibs stack up?

Design and specifications

Being part of the Mille range, comfort is the aim of the game with the Mille GTS S11 shorts. These shorts are built around the latest chamois in Assos’s Mille lineup, the GTS S11 insert. This is a dual-layer of high density foam materials, designed to be fast drying and coming in at 13mm thickness. One layer claims to absorb shocks while the other reduces vibrations. A 3D waffle perforated foam adds to this while aiming to enhance breathability and keep weight low, along with the KraterCooler holes in the top layer to "keep a cool microclimate", in the brand’s own words. 

Finally, there are two more catchily named proprietary technologies in the chamois alone. The whirlKrater, strategically placed perforations aimed to enhance airflow through the pad, and my personal favourite, the kukuPenthouse. This is a soft panel across the front of the chamois designed to allow greater cooling, eliminate pressure, and allow for a more aggressive riding position. Basically it is an area designed to give the male anatomy a little more room.

Building up from the chamois is the now commonplace feature on Assos shorts, the GoldenGate 2.0. This system attaches the chamois at the front and rear, but allows it to ‘float’ in the centre. This has a two-fold benefit of reducing seams around friction points and allowing the chamois to move with the body and maintain contact. This pairs with the rollBar feature where the straps of the shorts attaches to the top hem of the shorts, as well as onto the chamois directly, again aimed to keep the pad in contact with the body and reduce any form of friction. These straps also feature more perforations to improve breathability, and Assos’s signature X alignment at the rear.

The main fabric used on the shorts is Assos’s Volkano fabric. This is another proprietary material and provides both compression and abrasion resistance. Add to that UPF 50+ sun protection and Mineral Tec yarns to assist in odour control. Although offering compression across the legs, at the waist the shorts feature a more elastic version of the material designed to reduce any pressure around the midriff. Finally to keep the legs of the shorts in place, the PILtec plug-in hems are used. Low profile and more breathable, these use small silicone microdots to provide a secure grip even in the wet, rather than relying on elasticated hems. 

Being part of the Mille line-up, the fit is between the full Endurance fit and the racingFit, providing compression to a lesser extent and primarily focussing on comfort. Sizes are available between XS and 3XL with a long leg version offering 3cm greater coverage on the legs.

Performance

I have to admit I’ve been a big fan of the Assos Mille line of kit over the last couple of years, and these latest bib shorts have also managed to impress. The brand still uses a frankly ridiculous assortment of various proprietary names which will always require a lot of explanation. However, they all work together wonderfully to create a pair of bib shorts that are genuinely very comfortable.

Putting the shorts on there are a lot of small features which have an impressively big effect on comfort. The straps use a X pattern on the rear, where they cross over each other and then attach at the front. The spacing of the straps is quite wide where they attach at the front, meaning there is less of a pulling force on the front and nature breaks are incredibly easy with zero contortion required. I’ll go into more detail about how they also complement the chamois pad later. 

Using a more elastic waist at the front of the shorts also boost comfort further, with minimal pressure across the waist and soft tissue, something that has been uncomfortable before with certain pairs of tighter bib shorts. Especially when you consider that at high intensities you breath with the gut, allowing more expansion around that area makes a lot of sense. You don’t look so shrink wrapped when standing, but you also won’t feel a heap of pressure while riding and breathing.

I am also a fan of the new leg grippers, for the most part. The PILtec hems have an array of silicone grippers to maintain traction on the skin, but they do have limited effectiveness against much hairier legs, as mine are currently. I do however appreciate how low profile the leg hem is and the quite limited use of silicone, as I find it sometimes cause irritation across my skin. Being a more breathable material is also useful as I have experienced a lot of heat in the sun previously across the hem on a pair of previous generations Assos Equipe R shorts.

The main material is another triumph in warm weather performance. Named Volkano, it’s compressive, but to a lesser degree than the Equipe racing line, while also featuring abrasion resistance, which I fortunately haven’t tested. 

UPF 50+ protection, and odour control yarns are both features that greatly lend to the ‘long days in the saddle’ focus of the Mille range, and are not necessarily things you think you need until you start using them. Long term, these features should help with longevity of the shorts, but also yourself. I am glad to see more UPF protection focus on cycling kits.

In line with the temperature regulation focus, the straps also feature greater levels of perforation on the front of the straps. It’s an area that I have found an issue with some shorts where the straps are thick and get too warm quite easily. Temperature regulation has also been one of the main focus points for the chamois pad. 

It’s latest guise, The Mille GTS S11 pad uses the same GoldenGate fitting system that many of the brands shorts now use. Essentially the pad is attached to the shorts at the rear, and three anchor points at the front. This allows the side of the pad to ‘float’ and remain in contact with the body. Friction comes from two surfaces moving against each other, so making sure the pad stays in contact with the body means reduced friction and therefore reduced irritation. 

Added security comes from the rollBar, previously limited to the higher end GTO and RSR models. This means the rear straps actually attach onto the chamois pad to really lock it in place. It also has the added bonus that you can use the gap between the two rear strap attachment points to stow a packable jacket or gilet in a pinch, though this is naturally not going to be as secure as a pocket or a bag. 

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The chamois pad itself uses multiple layers of foam along with grid like structure and perforations both internally and externally. The whirlKrater and KraterCooler cooling features work together to create a greater level of airflow around the pad and better circulation, reducing the humidity of the seating area and reducing the likelihood of any build-up of bacteria. I can’t comment for certain how well this works, but I’ve never had a saddle sore when using Assos shorts that feature similar technologies, even on 8 hour epics and properly warm days. The chamois appears to work fantastically in this area as well as vibration dampening and shock absorption, something I can confidently say with the quality of some UK road surfaces.

My personal favourite bit of tech though is the kukuPenthouse, mainly because I can’t say it without smirking. This was introduced a while ago, on the old Mille S7 line of shorts, but it has been refined and improved. It’s a cut-out in the chamois pad where instead of foam there is a soft panel of fabric that reduces bulk and aims to limit pressure on the genitals for men. It does mostly work, reducing pressure and enhancing cooling in hot weather, it certainly cools the area when it’s cold. However, it does also lead to quite a prominent and defined bulge, more like a 100m runner’s leotard. Functionality wise it is effective, but volume wise it can still feel a bit on the high side, especially when hunched over, I think as the foam side panels press inwards. 

However, in warmer weather, along with the various Krater whatnots and breathable materials, all of these features work in wonderful harmony to create a pair of bib shorts that are brilliantly comfortable for big long days in the saddle, especially when the temperature hits above 20˚C, or even on the turbo where heat build-up is equally prominent.

Value

When it comes to the value of the shorts, this is an area where I am in two minds. £215 is a lot of money for a pair of shorts., Nowadays the £300 mark has been broken repeatedly when it comes to shorts, which is frankly excessive. I have a pair of the Assos Mille GT C2 bib shorts, which are £125, and in most conditions, there is very little that separates the two items. The chamois is comparable between the two, the fit and comfort levels feel incredibly similar, but the Mille GT are only a touch over half the price. There are also a host of shorts in that similar price range, such as the latest Rapha Core bib shorts, which are equally as comfortable.

Where the Mille GTS S11 standout, is in the heat. When the temperatures head north of 20˚C, the aforementioned cheaper bib shorts do start to become noticeably toasty. They’re both wonderfully comfortable for long rides when temperatures are lower, but in the heat they get too hot. Given that heat and sweat can add to bacteria build-up and friction, both key factors in saddle sore development, limiting those can really help comfort on long rides, but also maintain the seating area health over time. A saddle sore can take a week out of training, or derail a warm weather cycling holiday, so avoiding them may well be worth the additional cost. It's worth investing in some decent chamois cream too, to be honest, just to be safe. 

I maintain that £215 is not a cheap pair of cycling shorts, but the quality of materials and functionality of technologies and features does go a long way to justifying the price, especially when used in warmer weather conditions. If you want a pair of shorts for sub-20˚C though, you’re better off with a less technically advanced, but still very comfortable and cheaper option.

Verdict

With a real standout performance in warmer weather and more heated and humid conditions, the Assos Mille GTS S11 bibs are an impressive pair of cycling shorts. The proprietary technologies, fabrics, and features all marry together in a harmonious combination of great comfort levels and brilliant practicality.

They are an expensive pair of bib shorts, but not as extortionate as several in the market that have crept beyond the £300 price tag. For cooler weather conditions where airflow and breathability are not as important, there are several better value options. But if you want optimal performance in warmer weather and over longer rides, the Mille GTS S11 will not disappoint. Just be prepared to explain what a KukuPenthouse and try not to draw additional unwanted attention to that already highlighted area.