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  1. #26
    Senior Member Eclectus's Avatar
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    Try riding at 15 degs for 3 hours. Or randonneuring at 28 degs.

    There are lots of breathable water resistant / proof breathable fabrics and laminates. Entrant (3 kinds), Schoeller, Polartec Power Dri. Membrain II, Optik WxB, Hyvent, Hellytech...

    In all cases, the more breathable the material, the less protective it is in cold weather. The same pores and woven-thread gaps that allow H20 vapor to pass through, also allow N2 and 02 in the atmosphere to get inside, and the gas-transit correlation is linear.

    Moreover, the higher the H20 vapor transit rate itself, the higher the rate of body heat loss, because the vaporization of liquid water, that is the phase change, requires a lot of heat absorption, and then the heat is lost to the atmosphere as the H20 molecules leave the shell. So when you were riding at 28, your UA and Elite were keeping you from overheating by dumping a lot of heat. There are conditions in which this very high heat dumping rate is not desirable because it leads to hypothermia.

    Mountain Hardwear's newest iteration of Conduit has a moisture vapor transmission "breathability" rate of 40,000, vs. 20,000 for eVent. It's suitable for the Pac Coast and other relatively warm places. For their serious-cold shell, MHW uses Gore Tex Pro.

    66North used eVent for jackets and pants, now uses Entrant for jackets.

  2. #27
    Seņor Wences jwbnyc's Avatar
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    One of the limiting factors for me personally when riding in the cold is sweat.

    As the temperature gets down towards single digits, the number of layers needed to remain warm hits a point where, in combination with my Gore-Tex shell - an XCR jobbie I've had for a while, the rate at which water vapor is venting, even through vents, is insufficient to keep me from getting soaked.

    eVent has pushed the temperature at which this situation develops, again for me, much lower.

    In fact I haven't found out just exactly what temperature it takes to cause me to sweat out with the layers I use in conjunction with an eVent shell yet.

    It may be that the limiting factor will turn out to be heat loss not failure to vent enough moisture; but so far so good.

    eVent has it's uses as does Gore-Tex, but when it comes to passing vapor through a shell at a high rate, eVent does a good job of it and, at the same time, it does a good job of keeping precipitation at bay as well.

    Maybe it sucks for randonneuring, but eVent is quite useful for less extreme pursuits on a bike in my experience.

  3. #28
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    This all seems a little silly. If people go jogging at 20 degrees and there's no wind - do those guys wear a waterproof layer? I don't know for sure, but I don't think they do. I think they do just fine in a fleece or anything else that isn't waterproof or windproof, and "breathes" even more than eVent fabric.

    It also seems like a simple equation. Your body sweats because it's hot, to dissipate heat. So you're sweating a lot, and the theory here is that you're going to end up losing heat through the jacket. Well...that's pretty much the idea of sweating, to.

    If you need to be warmer, throw on another layer. A rainjacket isn't designed for maximum warmth or it would have an insulation layer. It's designed to keep you dry and keep the wind out. If you need more heat trapping ability, add it in the other layers.

  4. #29
    Seņor Wences jwbnyc's Avatar
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    A shell garment adds about Twenty degrees of warmth.

    IOW, if you are comfortable in a particular shirt at 70 degrees, just standing around in calm conditions, you'll most likely be comfortable in the same shirt and a shell in 50 degrees, making allowances for different metabolic rates.

    The degree of warmth provided by a shell garment goes up exponentially when wind chill or precipitation is added to the mix.

    You can get by with fewer layers, and less sweating, with the right shell, when the conditions warrant it.

  5. #30
    Senior Member Eclectus's Avatar
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    eVent is breathable because it is basically the original Gore-Tex (porous or expanded polytetrafluroethylene, aka expanded "Teflon"), which was highly breathable, but tended to foul quickly with sweat oils. Gore devised a porous polyuethane coating which reduced the initial breathability by 50% by partially closing GTX's pores, but greatly slowed wearer-induced GTX clogging.

    When GTX patents ran out (1996 for ePTFE, 2000 for garments using ePTFE), GE and some other companies jumped to make generic GTX. GE's version had a new molecular treatment. So eVent users are actually praising GTX, as a core material.

    There are some reports from multi-year users that GE's GTX III, I mean eVent, does clog up faster than Gore's own new versions. Good idea to get NickWax wash and re-proofer when that new shell starts to feel clammy.

    Another interesting fact is that manufacturers using eVent, for example Rab and Westcomb, put pitzips on their topline eVent jackets, but not their lower-tier ones. This doesn't mean the budget models' eVent is more breathable, but rather that the companies use thicker fabrics for increased durability (packstrap-wear shoulders, chest and back) for topline jackets, and more pockets, and that decreases breathability. So, getting the best fabric breathability means trading off durability.

    Which brings up a final issue about anecdotal testimonials. You can't compare GTX to eVent without using identical designs, and nobody has made identical jackets to test. Secondly nobody has done real scientific tests, putting people on stationary bikes in wind tunnels, varying virtual cycling speed, air temps, humidity, artificial rain, and measuring skin temps, inside-shell humidity, and sweat loss (weigh people and clothes before and after test rides).

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