Marmot Ion Windshirt - a review

I wrote this review ages ago back in the summer, after Marmot had sent me a few test items to try including the Ion. For various reasons beyond my control, UKclimbing didn't put the review up. I was reminded of the piece now after seeing a post by Andy Kirkpatrick again talking about using windshirts as part of a wider clothing system (see the last paragraph of this review as well). I was wearing the Ion today whilst ice climbing (pic below) over a heavy merino base and under a Marmot Genesis softshell, and it works great. You don't really need the windproofing under a membraned softshell like the Genesis, but it is so slippy as an underlayer, the sleeves on the Genesis don't pull down as much when reach high with your tools when using the Ion.

Ice climbing at Kauhala today - the Ion shirt is under the Genesis softshell

So my review from back in the summer was as follows:

Lightweight, unlined windshirts are probably the best value items of outdoor clothing available if you balance their weight in your pack and their cost on your wallet – both minimal – against the protection and comfort they provide. They are great for mountain routes both in the UK or alpine areas; I use one for walk-ins and as an extra protection layer for grim winter climbing and also on sweaty ascents when ski mountaineering. Weighing so little it is easy to chuck one in your pack when summer cragging, just in case the wind gets up or for when the sun goes down. Additionally I use one for cycle commuting in cool and damp weather, when mountain biking, hill walking, for the rare occasions when I force myself to go running, and when cross country skiing. You probably get the point by now – there are really very few times doing an outdoor activity when a windshirt won’t come in handy. So if you are going to get one you might as well get a good one. So what make one good?

Firstly, a windshirt rather self evidently has to be windproof. Almost all are made of some sort of lightweight, close-weave nylon and there don’t really seem to be degrees of ‘windproofness’ – they all are; unlike some slightly thicker softshell materials that seem to be of a slightly looser weave and offer noticeably less wind protection. Therefore, leaving that fundamental to one side, the most important consideration becomes how breathable the material is. From rather bitter experience, I know it is very hard to tell in a shop just how breathable various lightweight nylons are and this is one of the reasons that I was so interested to try this year’s Marmot Ion windshirt. About three years ago I bought that seasons version of the Ion. It was an excellent fit, had all the features I wanted and none I didn’t, was super lightweight and being sold at a good discount at the time. It seemed the perfect replacement to my aging Pertex windproof; that was until I went running in it. This was running a muddy ten kilometers through the Worcestershire countryside on a driech Christmas morning. Whilst the drizzle beaded up nicely on the outside, through the very thin fabric I could actually see my sweat beading up on the inside of the jacket. About halfway through the run I stopped to take off the jacket that was wet to touch on the inside, and had wetted out my baselayer beneath – exactly what you don’t want. I asked on the UKC forums and a few others had found exactly the same issue, and also provided a link to one of the US-based backpacking forums where exactly the same problem was being discussed.

This year’s Ion is a different material, the same as Marmot use for the shells of their excellent Driclime range. Now the Ion breathes perfectly; just as well as Pertex, which is my benchmark for this kind of fabric. I sweat a lot when biking hard, but the Ion didn’t get any more than slightly clammy inside. Having got the fundamentals right, everything else on the Ion is just a bonus. As outdoor gear becomes progressively better designed, cut and manufactured, fit becomes more important to what works best for you. Marmot’s clothing tends to fit me well, I find some other firms cuts are for people who are both taller and skinnier than I am. Nevertheless, despite fitting my stout frame, the cut remains a trim, athletic shape. There is no flapping under the arms or around the midriff, even when cycling. Other multi-sports types will be glad to hear that the designers seem to have kept cyclists in mind. The sleeves are plenty long enough when holding onto handlebars and the back doesn’t ride up. So even though it isn’t a cycling specific jacket it does that job well. There is also no riding up when climbing in the jacket. The Ion has a hood; it is not big enough to go over a helmet but, being such light material, it could easily go under a helmet on a breezy belay. The hood can be rolled down although the securing strap isn’t very tight and it can slip a bit. I found that when cycling, the breeze would loosen the hood and make it flap around. There is one small chest pocket which the jacket packs into – this has a loop on it so, once packed up, the Ion can be clipped to a harness. The cuffs are elasticated but can be pushed up if you are hot. That is about it; for example, in the interests of being lightweight, there is not even a hem drawcord on the jacket.

Overall, the Ion is a great windproof layer. It is both very light and breathable, packs down to nothing but still gives huge amounts of protection against the wind and some limited protection against drizzle. It has virtually no features, but then it also weighs under 150 grams, which to most is far more important. In this case, less really is more.

A top-tip: For those who warm-up easily, a windproof over a baselayer is often all you need for walk-ins to winter climbs. But once you get to the climb don’t take it off and stuff it in your pack. Keep it on over the baselayer and then stick your softshell over the top. The smooth nylon means there is no binding between the layers, and in my experience, non-membrane softshells at least, don’t tend to be completely windproof, so the keeping the windproof jacket on under the softshell creates a cosy micro-climate further in whilst not compromising the breathability of your system. This idea is based on what Andy Kirkpatrick call the “comfort layer” of his super alpine system but being two pieces instead of one, it’s slightly more flexible for less gnarly conditions.