Assos Mille GTO C2 bib shorts review

There is only a very small group of premium bib shorts designed for endurance riding instead of racing. Often the top-of-the-line offerings have short distances and all-out speed in mind. The Assos Mille GTO C2 is one of the few that's as premium as you can get but not made for racing, and instead of wind tunnel numbers, you'll find features for ticking away the hours in the saddle. 

Aside from being a long-distance, endurance-focused bib short it also perfectly encapsulates the Assos reputation. If you know Assos you will recognize the premium pricing, unique textiles, and ultimately the focus on the chamois. It's a brand that follows a formula even when they are doing something different and the Mille GTO C2 doesn't stray from the formula. The question is always, does it work in this case? Keep reading to see our thoughts on the design and how they stack up against the best cycling shorts on the market.  

Design and aesthetics 

You don't have to be familiar with what Assos has offered over the years to understand these bibs. If you are though, it all makes sense. The whole design is a crescendo of everything that Assos has been doing for the last few years but taken a step further. Most of what you see isn't new but instead tested for years then combined with new details. 

What's truly new is the chamois design. Not only is it new, but it's also the focal point of the bibs and a perfect place to start talking about what makes the Mille GT GTO C2 different. The construction uses a technology called the goldenGate which has been a mainstay of Assos as far back as 2013 and makes the underside completely accessible. The idea behind goldenGate is to allow the chamois to move separately from the rest of the bib short. Instead of stitching the entire edge of the chamois, there's strategic sections of stitching followed by large openings. It keeps the chamois with your body even when you are standing and moving around in the saddle causing the fabric of the legs to shift and pull. It also makes it easy to inspect the chamois from both sides. 

Looking at the chamois you can see the layered construction. The first thing you can see is a thin fabric backing then the bulk of the piece is an 11mm thick piece of white foam Assos calls microShock. 11mm is already thicker than many chamois designs but the "twin21 system is made of three separate layers." As you move farther from the saddle the next layer is 10mm of "filterFoam." You can't see this piece but it's described as "lower-density matrix foam." 

In case you aren't keeping track, that's already 21mm and it's not actually all the layers. Conventional wisdom is that a pad that thick shouldn't work, but unlike a cheap overly-padded chamois, Assos has used specific densities stacked in a way that works together - in other words, it's much more than just a thick piece of foam. The other piece that helps make it work is a technology called whirlKrater. The name refers to a system of strategically placed holes to boost air circulation. You can see them in the top layer of thin foam but there are also holes that run through the microShock and filterFoam layers. 

In the lower layers, the holes are in the rear section and are large enough to put your index finger through. At the end of the holes you can feel the third layer of the chamois called the "3D-waffle" layer. Assos refers to this layer as a "next-to-skin 3-layer perforated foam" however the important part isn't actually next to your skin. Instead, it sits below a final fabric face. The 3D-waffle layer does allow air to circulate below this final layer though and it helps keep the fabric that touches your skin dry. 

Looking at the top of the chamois it's a baby blue colour and you can see the stitching highlighting six articulated sections. There's an open area through the center then three pieces on each side that can bend to match the shape of your body. At the front and sides there's only the final 3D-waffle layer with the whirlKrater holes. Move to the very front and there's something called the "sundeck superlight."

This section at the very front of the chamois is one of the things that makes these bibs so recognizable as an Assos piece. The description says it's "made using an ultrasoft foam-free textile to form a preshaped cup that both supports the male anatomy and promotes maximum ventilation." It's a design that is new but recalls the kukuPenthouse introduced on the S7 bib shorts way back in 2013. In this case, it's a soft single layer of fabric attached to the outside of the bibs and the front of the chamois. 

Flip the Mille GTO C2 back to the outside and you get a sense of one of the strongest points of the design. The fabric used to construct the body of the bib shorts is something Assos calls Ossidia. The goal of this fabric is to strike "the ideal balance between frictionless comfort and muscle-supporting compression." What that ends up meaning is that it's one of the thicker fabrics used for bibs and it's got a lot of stretch to it. The density helps it to stretch without ever feeling thin. 

The entirety of the bib shorts, aside from a specific groin panel, is a single piece of fabric folded on itself. Up the back of each leg there's a seam that continues across the low back then down the opposite leg. There's also a seam that bisects the chamois and there are darts at the side of each leg and near the crease at the top of the thigh. Using a single piece of fabric is incredibly complex and has to mean more waste but it also ties into how the straps work. 

At the rear, the bibs attach using A-lock construction. This means that they connect in two places. The first is at the very bottom of the back just above the chamois. Then there's a large section where it's unattached before the second attachment point. The second attachment point is at the top of the main body and roughly where most bib straps attach. Because the whole body of the Mille GTO C2 bibs are a single piece of fabric, these two points of attachment lock in the fit in a way that wouldn't otherwise be possible. 

Keep moving up and the straps cross in the mid-back before heading down to the front. In the front, the attachment point ties in the main body of the bibs as well as the separate groin panel. The groin panel is a different fabric with a different feel. Visually it features a diamond pattern and functionally the “Losanga fabric” is less compressive. It's an "Assos-developed textile that eliminates pressure against sensitive areas."

As you move down the legs, another ever-present design choice is the silicone grippers. Instead of strips, small dots, or even something solid, Assos chose large circles. The spacing is wide and starts above the hem at the edge of the shorts. The pattern is four dots wide and wraps around the leg leaving about a quarter of the distance without any dots. Functionally there's no real difference between other configurations but you can see the dot pattern when you look down.

Ride experience 

Describing the Mille GTO C2 bib shorts and running through all the technologies takes a lot of words. There's no way to think about these and not understand that they are incredibly complex and possibly over-engineered. At the end of the day though it all has to work, so what does it feel like to ride with these?

For a review like this, I love to do something big to really put it to the test. I can only realistically ride 400-mile weekends a few times a year though and these just missed one. I started using them for rides in the 30-50 mile range to get a feeling for them. My sense was that I would have been happy to trust them with those ultra-distance rides as well but I wanted to put together at least one full day of riding to really test them out. With that in mind, I came up with a hybrid indoor/outdoor approach. I spent three hours on the trainer then took them out on a gravel ride for another three hours. Each piece is a real torture test for bibs but in different ways. 

Putting these on it's truly surprising how thick the chamois is. The concern with a chamois this thick is heat build-up, which is why I started testing on an indoor trainer, since it provides a good test of how a chamois can handle the heat with minimal airflow and combined with a very static ride position.

None of the other long-distance-focused bibs on the market take this approach but it seems to work here. There was never an unpleasant build-up of heat. Instead, I found myself far more focused on the padding. What I found with these is that while the thickest part of the chamois is at the rear - and only realistically gets used in a more upright position - there's still padding where you need it. Rotate your pelvis forward as far you want, even in a time trial position, and there's still padding under your sit bones. 

Getting out on my gravel bike is a much different kind of test. The more upright posture of my gravel bike means I'm more engaged with the thickest part of this chamois. In this posture, the multiple layers do a great job of soaking up vibration. There's also plenty of density to keep you from developing hot spots even when your saddle has no padding. 

One thing that's noticeable is that the "regular" length available for these bibs is shorter than most of what's on the market, so after a long summer of wearing modern standard length bibs, there was a noticeable gap between the end of the Assos bib shorts and my tan line. It works well in gravel guise. Under a pair of Gore Wear Explore shorts, it's a perfect length to stay hidden. If you prefer the more modern length of most other bibs though go with the long version of these. 

Above all, the best part of the Assos Mille GTO bib shorts is the feel of the fabric. It's incredibly soft and there's a ton of compression. That compression is intentionally lacking on the front panel covering the groin and abdomen, and the balance Assos strikes between high compression everywhere else and low compression here is impressive. On a road bike with more aggressive geometry, it’s very noticeable how that panel responds to the placement of the straps. It remains taut without hindering breathing and you get the added bonus of a flattering silhouette when bent low. 

Verdict

Put simply, if you ride long distances on your bike, the Assos Mille GTO C2 is an excellent option.

There are only a few competitors, and these take a different path to the end result courtesy of the high volume chamois, but it works exactly as intended to offer incredible levels of comfort on the longest days in the saddle. 

And just like the chamois, everything else follows the same story of working exactly as it should. The goldenGate technology that allows the chamois to move with your body is something you can feel when riding. The single-piece pattern design paired with the way that the straps lock-in at multiple points works really well. The fabric choices are top-notch. Each piece of the concept is well executed.

Tech Specs:  Assos Mille GTO C2 Bib Short  

• Materials: Main body: A single sheet of Assos exclusive Ossidia fabric in a butterfly configuration. Front Panel: Losanga proprietary textile with lower compression compared to the main body
• Size availability: XS-XLG and TIR (XLG but wider)
• Length Options: Standard and Long (+3cm vs standard)
• Price: £255 / $350 / AU$449 / €290