Assos Mille GT Eisenherz Ultraz Winter Bib Tights S11

The Assos Mille GT Eisenherz Ultraz Winter Bib Tights S11 are superb – very warm, very comfortable, breathable and innovative. However, as you might expect with something that performs this well and has an Assos label on the bum, they don't come cheap – though there are still two pairs above them in the Swiss brand's lineup.

For more ways to protect your legs in the cold, check out our guide to the best winter bib tights.

The Mille GT Eisenherz Ultraz Winter Bib Tights S11 might have the longest name and cost over £300, but they're almost mid-market in the Assos hierarchy of bib tights, with the Equipe RS and GTO Winter bib tights both coming in more expensive. However, these are not mid-market in terms of performance by any stretch of the imagination, and in fact are probably the best bib tights I have worn in over 10 years of reviewing for road.cc.

Their construction is unlike any other bib tights I have tried, the legs being made from two separate layers, with only a seam at the back of the leg connecting the two. I've seen this kind of thing in jackets, with an insulated gilet inside a weatherproof shell, but never in bib tights.

The outer layer is made using Assos' Sphere Ultra softshell material purely for weatherproofing, providing protection from the wind and rain, with no thermal properties. It's very effective at stopping cold air getting through, and as it's water repellent (in fact Assos calls it waterproof) I stayed nice and dry too. I did a fairly rudimentary experiment with these and ran them under the tap for over a minute and nothing came through, so unless you're going to try to use them as a wetsuit, they will keep everything out.

Inside Assos uses a thermal material, RX Extreme, which sits against the leg and boasts very impressive thermal insulation. Breathability, too, is excellent; the material doesn't need to do everything, so it can be more specialised than just a single layer (although it also water resistant, just in case). There are materials that can do everything, as used on many other bib tights, but by having the layers completely separate, each can be thinner and more pliable, meaning that movement is more fluid and comfortable. When you first put these on, they feel considerably lighter and more malleable than you would expect.

The higher-than-standard waist panel is made from Assos' Winterfoam, a stretchy fabric that offers impressive warmth and extends down to below the groin, meaning all the most important areas are well protected.

Up top Assos has continued with the same design that we've seen in its other bib shorts in the past couple of years, with everything above the waist just being straps.

These are wide, stretchy, and comfortable on the shoulders, and the lack of mesh or any back panel means they are both excellent for breathability and allow moisture to wick better from baselayers.

Chamois

Assos has used its Mille GT S11 pad in these tights, which employs the goldenGate 2.0 attachment technique that allows the pad to move with the body rather than the garment. Basically, Mips for your bum. I have a pair of bib shorts with the initial design and they're supremely comfortable, and the updated system – with cutouts on the wings to reduce friction – offers just as much comfort if not more.

The pad is very comfortable, made with a 12mm-deep damping foam designed for endurance and paired with the 3D waffle foam that has been a staple of most Assos pads for the last few years.

It results in a pad that is both comfortable for long winter miles and also has impressive breathability and wicking, which is particularly important when trying to keep in warmth in winter kit.

I used these for both short, sharp, 'fit in as much as I can, as hard as I can' sessions and longer, more sedentary training rides and found the pad supremely comfortable for both.

Away from the pad, these are also comfortable because of the fleecy lining, which feels great against the leg.

It's also worth noting that they seem to not attract static, which is great; with their overlapping system of two materials, I was slightly concerned that I would end up shocking somebody every time I went near them.

Despite having two layers, the tights still have a very close, streamlined fit – the material has a good amount of stretch, which allows it to wrap around the contours of the body without creating excess folds or creases. The legs also have a raw cut at the end rather than a hem, creating a more svelte finish.

Value

At £305, these are the most expensive bib tights we've reviewed on road.cc, but they are also undoubtedly the best bib tights I have ever worn, offering a combination of warmth, breathability and ease of movement at a level I've never experienced before. So while they're a lot of money, I don't think anybody who buys them will feel like they've been ripped off.

And they're not actually that much more than some of the very high-quality pairs we've tried out over the last few years...

MAAP's Team Evo Thermal bib tights, for example, are now £260 – up from £230 when Jamie reviewed them in 2022 – and we reviewed Rapha's Pro Team Winter Tights with Pad II back in 2019 and were impressed; they are still in Rapha's lineup today, also with an RRP of £260.

Conclusion

As I said above, these are, without a doubt, the best pair of bib tights I have ever used. They are innovative, warm, comfortable, and allow for an unparalleled ease of movement in the pedal stroke. By using two layers, Assos has allowed both layers to excel rather than trying to find one fabric that will do everything, and meant I could comfortably use these on the coldest days without any concerns. However, this performance comes at a high price that puts them out of reach of many.

Verdict

Superb and innovative bib tights with a big price tag