Assos GT Ultraz Winter Booties review: Deceptively capable overshoes from the Swiss brand

Assos makes some of the most technical and specific cycling clothing on the market and has done for a long time now. Pieces often have very specific uses and its equipment often takes a little more research to understand and identify the best piece to match to your requirements. I tested the Assos GT Ultraz booties this winter and have spent several months using them as well as a range of other overshoes many of which you can find in our best cycling overshoes guide.

So it’s about time I write my review as we hopefully head (I say this with bated breath) towards the spring thaw in the northern hemisphere. The Ultraz GT is the most heavyweight overshoe from Assos and the brand says they are designed for protection in the harshest winter conditions. They sit alongside three other overshoes in the range as well as a pair of toe covers.

Priced at £90 / $120 / €105 they do sit at the upper end of the overshoe pricing range. Specifications: Assos GT Ultrz Winter Booties Price: £90 / $120 / €105 Material: Outer: 100% Polyester / Inner: Polyester / Polyurethane Available sizes: 0, I, II Colours: Black Design and Aesthetics The Ultraz GT use what Assos calls a dual-layer twinDeck textile construction using Assos ThermoShell textile The overshoes are constructed from Polyester and Polyurethane and don’t feature neoprene. Externally the material is soft and features a small square pattern.

Inside each overshoe is soft, really soft, brushed fleece, and the front section from the two rows of stitching around the middle of the foot onwards features a material that’s thicker than it appears at first glance. This is the Assos twinDeck construction. The ankle is around 15 centimetres long which is a similar height to the Sportful Fiandre Bootie.

The Ultraz feature a camlock zipper with an Assos logo plastic logo zipper cover which has textured dimples on the reverse, it’s small details but it helps you pull everything up and into place as you zip up. Camlock zippers can be overlooked but are impressive – flick the zipper to its most downward position and it will not undo, you need to lift it up to zip down. Useful in preventing unwanted unzips on the bike but in reality I just put the overshoes on and off and didn’t particularly need this much.

There’s also a round internal flap that sits over the top of the zip to prevent any rub happening here. Branding is low key, there’s a plastic Assos logo roundel sewn onto the outside front of each overshoe and up at the ankle there’s an Ultraz Winter and Clima Code 3/3 textured logo on the right and left overshoes respectively. Equipment featuring the 3/3 logo features in the Assos winter collections.

The top of the overshoes features a sort of open hem which lies really flat against your bibtights or legwarmers and makes for a smooth transition between the two, Assos calls this its zeroCuff. There’s an internally and externally reinforced toe section for protection when walking off the bike and the heel and cleat openings are neatly finished. A note on Assos sizing for the uninitiated.

Available sizing is 0, I and II. Size I equates to an EU 40-43 size. Assos has a great size calculator on the website though.

Assos pendulum zipper closes the overshoe up at the zeroCuff (Image credit: Future) Performance I’m based in the UK and generally speaking for the most part it gets cold in the autumn and stays cold for months through the winter. Our roads tend to stay wet, and lanes are often in poor condition with lots of grit and debris, not to mention standing water and puddles meaning lots of spray. From childhood, winter cycling has just meant neoprene overshoes for me as a best-for-most conditions solution (not to mention a lack of choice back in the day).

I don’t know, but I think most British cyclists get ready for winter training and just pull out the neoprene overshoes. I know I have for years, and I surmise this could be true of cyclists in other countries with similar wet, cold winters. My hard-wired outlook here initially made me think that the GT Ultraz couldn’t possibly be up to the task of dealing with hard, cold winter conditions when compared to other brands’ heavier weight and in most cases literally heavier offerings.

Enter the Assos magic. I’ll start by mentioning my previous point here that Assos equipment is often highly technical and pretty specific. My first ride out in the GT Ultraz was on a wet Saturday morning club run, with standing water, several fairly heavy showers and plenty of fellow riders not running mudguards, I ended up with wet feet fairly quickly and wet feet = cold feet after a while.

The overshoes have a DWR (durable water-repellant coating) but they won’t deal with a downpour or heavy rain too well I found. I didn’t quite write them off but my initial impression was along the lines of “got wet feet, too thin, not warm enough” this was an incorrect conclusion. Nevertheless, as Winter arrived I stuck at it and on cold, dry rides the Ultraz started to come into their own, and provide a really surprising level of warmth for their weight.

Less bulk on the bike is just fine by me so If I can wear a lighter weight overshoe whilst keeping my feet warm I will. On dry days when the roads weren’t in bad condition and largely dry, I found myself reaching for the Ultraz regularly. They’re sleek and stylish on foot and as mentioned are lightweight but I haven’t got cold feet or toes once in temperatures comfortably in single figures.

This has really surprised me considering their relative thinness and weight. You just wouldn’t expect it at first glance. They have worn well and don’t show any signs of tearing or damage underfoot.

The only area worth keeping an eye on going forward for me is the open zeroCuff, which has a few loose strands coming off it, and I fear in time will begin to look a little tired. All Assos products are supported by a two-year warranty and there is a crash replacement scheme should the worst happen. From the central stitching forward the material gets a lot thicker and this adds warmth.

Note the reinforced toe area. (Image credit: Future) Verdict For me, the GT Ultraz booties are a really great choice for dry days when the roads aren’t soaking. If it’s dry they do a great job of insulating your feet without adding lots of bulk to slow you down.

I really enjoy wearing them and they look super stylish. I’m still surprised by their warmth. They are expensive and wouldn’t be my first choice in wet conditions.

If you are happy with the price or can find a deal online they will offer great dry-weather performance if you want to add them to your arsenal. Not one for soaking days, however. The Ultraz cut an unassuming figure but pack a punch (Image credit: Future).