Wich windshirt is the most breathable?

Hi Rene.
I notice the jacket has a PU coating. The PU will give better rain protection, but make it less breathable. I would look for a windshirt without any PU coating. Montane have a few Pertex windshirts that are highly rated. I see you are from the Netherlands, so you shouldn't have any trouble finding Montane gear.

I'd say Pertex Microlight is extremely breathable. As mentioned, Montane makes some good ones, as does Haglöfs and VAUDE.

The Montane Slipstream is available right now (stateside) for less than $60 (Bing gives another ~$7 back), and that's 3 oz. of Pertex Quantum windstopping… I've been seriously considering one, as I've been really happy/impressed with the Montane gear I've seen/used so far.

http://www.backcountry.com/outdoorgear/Montane-Slipstream-Jacket-Mens/MNT0021M.html

Is there anyone here who has used both Montane and Montbell windshirts and can give a comparison of the two? Montbell I know makes theirs out of a 15D ripstop nylon with a polkatex DWR that's supposed to stand up to a lot of abuse. I haven't used the Pertex Quantum to know how wide the difference is between these two fabrics.

I have a Montane Aero (my size large is 2.9oz)made of Pertex Quantum that I have really liked. The Patagonia Houdini is also supposed to be very breathable.

Are breathability and high wind resistance mutually exclusive in a wind shirt (wind breaker) ? not sure on the physics involved here.

I tend to wear a wind shirt for fairly dry windy weather to cut down on the wind chill. Don't care about waterproofness as I go to a real rain shell in wet weather.

Can I have the best of both worlds ?

Breathability typically refers to water vapor transmission. Wind resistances is about air flow. In the real world, high air flow gives us the sense that there is better breathability. In labs testing breathability there aren’t 20mph winds, so air permeability has a smaller impact to the breathability numbers.

I like the What Precent of Naked? by Patagonia.

–mark

I actually just came back from a run with the montane marathon jacket.
Its made of Pertex Microlight, and was especially designed for high aerobic activities. If you don't mind the slight weight penalty, this is probably one of the most breathable windshells around.

You can find it at http://www.backcountry.com/outdoorgear/Montane-Featherlite-Marathon-Jacket-Mens/MNT0022M.html?CMP_ID=SH_FRO001&CMP_SKU=MNT0022&mv_pc=r126

Though its listed at 4oz, in reality its more like 4.6 oz (size small) before any trimming. The weight comes from the fact that it has 1)reflective piping along the zipper and sides and 2) extra fabric to create vents along the sides of the jacket. Under each arm are a set of 'gills.' Its similar to pit zips, but always open. (2 on each side, 4 total). And they make a huge difference.

So right now the weather in Boston is 45 degrees, with a little wind (was running by a lake). I was able to comfortably run 1.5 miles at a 7 min per mile pace, in this jacket. I wore it over a patagonia long sleeved capilene 1. I did not sense any clammyness, and it kept me substantially warm. I was able to run with the zipper all the way up to my chin and fully closed for the majority of the time without feeling a sense of overheating. I've done the same run, at a slower pace in a marmot ion and had wanted to take the ion off after the first 5 mins. The ion is the 2009 edition, using Banshee fabric.

I was stuck between this jacket and the montane slipstream. Since I wanted a jacket that i would mainly use for running, and not just hiking, I chose this one. Its worth the extra oz and a half over the slipstream if you want superior venting/breathability and safety (Reflective piping is a blessing when you run among crazy boston drivers). However, If I had wanted just a windshell for hiking, I would have opted for the lighter slipstream, as I emit much less body heat while hiking, and would likely have no need for the side vents of the marathon jacket. Seeing as how the manufacturing specs are off for this product, i wouldnt be surprised if the slipstream weight more like 3.5-3.7 ounces