Cotton or Poly in this Heat?
07-28-22, 09:34 AM
#26
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Agreed that cotton is good for sitting around relaxing or for casually strolling around in hot weather. But for most sport cycling, synthetics are clearly superior, as attested by the majority posting in this thread.
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07-28-22, 10:07 AM
#27
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I disagree (to put it mildly).
For cycling in the heat? I haven't worn a square millimeter of cotton while cycling in decades, whether hot or cold. In fact, I don't wear cotton while cycling, hiking/backpacking, skiing (Alpine or Nordic), snowshoeing, playing tennis, running or any physical activity.
Cotton is fine for temperate conditions, for leisure activities and for office work clothing. But if it's hot or cold, or if you're doing any sort of physical activity for more than a few minutes, wool or synthetics perform far better. Cotton stays wet, bunches up and causes chafing/blisters (cotton socks are particularly evil), is clammy to the touch and holds moisture against your skin, and is heavy as heck. The last time I wore cotton while backpacking (cotton underwear and t-shirts; everything else was wool or synthetic), I was miserable. It rained frequently that week, I couldn't get any of my cotton clothing dry. On (what turned out to be) my last day is started sleeting heavily (at that point, I turned around and went back to the nearest road, hitchhiked into town and found a place to stay; went home the next day). This was nearly 30 years ago, and since that day I haven't worn cotton during any sort of extended activity.
I have no experience with desert conditions, so maybe this does not apply for cyclists in dry climes.
For cycling in the heat? I haven't worn a square millimeter of cotton while cycling in decades, whether hot or cold. In fact, I don't wear cotton while cycling, hiking/backpacking, skiing (Alpine or Nordic), snowshoeing, playing tennis, running or any physical activity.
Cotton is fine for temperate conditions, for leisure activities and for office work clothing. But if it's hot or cold, or if you're doing any sort of physical activity for more than a few minutes, wool or synthetics perform far better. Cotton stays wet, bunches up and causes chafing/blisters (cotton socks are particularly evil), is clammy to the touch and holds moisture against your skin, and is heavy as heck. The last time I wore cotton while backpacking (cotton underwear and t-shirts; everything else was wool or synthetic), I was miserable. It rained frequently that week, I couldn't get any of my cotton clothing dry. On (what turned out to be) my last day is started sleeting heavily (at that point, I turned around and went back to the nearest road, hitchhiked into town and found a place to stay; went home the next day). This was nearly 30 years ago, and since that day I haven't worn cotton during any sort of extended activity.
I have no experience with desert conditions, so maybe this does not apply for cyclists in dry climes.
What you needed for that experience was wool.
Cotton is ideal for arid climates, which include hot and dry, and very cold and dry. It is the choice for the Arctic and Antarctic both (not as insulation but for the shell).
As far as cycling, I admitted it has a considerable drawback in aero drag and that rules it out for most high-speed cyclists. Merino was the choice of these cyclists until synthetics advanced enough. Make no mistake though, no synthetic is as good as cotton for extreme heat. It's only when the criteria of low aero drag is added that the compromise of Lycra has appeal.
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07-28-22, 10:34 AM
#28
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My wife and I made it through Phoenix on a hot summer afternoon on the motorcycle by doing a full-body wet-down of our cotton jeans, shirts, and jackets. They were dry fifty miles later. More than once I've soaked my cotton T-shirt for cooling off while hiking. That can really work against you in cold weather, however. But, cotton jeans don't get wet in -20 degree snow, either!
That said, I wear mostly Pearl Izumi synthetic clothing while riding these days, and it works well, as it ought to, for the expense. Patagonia Capilene long underwear, too.
Ben Franklin supposedly said: "I eat to please myself, but I dress to please others".
I'd go with: "Suit yourself".
That said, I wear mostly Pearl Izumi synthetic clothing while riding these days, and it works well, as it ought to, for the expense. Patagonia Capilene long underwear, too.
Ben Franklin supposedly said: "I eat to please myself, but I dress to please others".
I'd go with: "Suit yourself".
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07-28-22, 11:24 AM
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I am very happy with a Fieldsheer Mobile Cooling shirt and neck gaiter. 50 SPF UV protection, vented back and underarms, no odor, very comfortable. Riding generates enough breeze for the garment to keep me cool. It's a synthetic fabric, not sure what the technical specs are. Available in various colors. I choose neon yellow for riding.
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07-28-22, 02:03 PM
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07-28-22, 02:08 PM
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What you needed for that experience was wool.
Cotton is ideal for arid climates, which include hot and dry, and very cold and dry. It is the choice for the Arctic and Antarctic both (not as insulation but for the shell).
As far as cycling, I admitted it has a considerable drawback in aero drag and that rules it out for most high-speed cyclists. Merino was the choice of these cyclists until synthetics advanced enough. Make no mistake though, no synthetic is as good as cotton for extreme heat. It's only when the criteria of low aero drag is added that the compromise of Lycra has appeal.
Cotton is ideal for arid climates, which include hot and dry, and very cold and dry. It is the choice for the Arctic and Antarctic both (not as insulation but for the shell).
As far as cycling, I admitted it has a considerable drawback in aero drag and that rules it out for most high-speed cyclists. Merino was the choice of these cyclists until synthetics advanced enough. Make no mistake though, no synthetic is as good as cotton for extreme heat. It's only when the criteria of low aero drag is added that the compromise of Lycra has appeal.
gm
07-28-22, 08:00 PM
#32
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07-28-22, 08:06 PM
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Cotton is for casual activities and moderate conditions. In the heat, it traps sweat (does not evaporate easily) so keeps you too hot. In the cold it likewise traps sweat, and in this case keeps you too cold. It's great in spring and fall. For really hot days I like synthetics, and cold days I like merino wool, especially SmartWool brand.
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07-28-22, 11:18 PM
#34
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Depends upon where you live and how you keep cool. Before I retired and when I had to ride in the afternoon in summer, the only way I could ride any distance safely was to ride wet. Fortunately water sources are easily accessible at local parks. It would take about 5 miles to go from soaking wet to bone dry. Even with temperatures around 100 it was chilling to put on a wet t-shirt. This works in areas with low humidity. Cotton was my fabric of choice because it holds a lot more moisture than synthetic fabrics. If you are solely relying on sweat for cooling and live in a humid area I agree that the wicking fabric are better. Here it really doesn't matter as even cotton stays dry because of the fast evaporation rate. It is way to easy to dangerously overheat relying on perspiration alone.
Might actually try cotton shirt and wet it and see. Thanks for the tip!!
07-29-22, 03:55 AM
#35
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My synthetics still dry up way too fast even in high humidity >70%. And I'm already wearing light colored or white shirts that reflects sun's heat. Maybe it's the rolling hills, the shirt drying up in fast downhill.
Might actually try cotton shirt and wet it and see. Thanks for the tip!!
Might actually try cotton shirt and wet it and see. Thanks for the tip!!
In a hot dry environment, where the ambient air temperature is approaching or above body temperature, a wet shirt can help because that moisture is absorbing the heat from the air, before it gets to you.
In a very humid environment, the moisture has a harder time evaporating. A synthetic shirt will carry sweat off your skin, and also give it more surface area to eventually evaporate. A cotton shirt will absorb this moisture, and the excess body heat that comes with it, and not release it to the air. Have you ever noticed how heavy a wet t-shirt gets, or how long it takes to dry out?
I've spent most of the summer working in Louisiana, wearing FR-rated (100% cotton) work clothes, and it has been miserable; they stay wet for hours
There's a reason that there are almost no clothes intended for active/athletic use (like cycling) that are 100% cotton, and it's not marketing.
07-29-22, 07:40 AM
#36
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Wet cotton sucks, but it conducts heat a lot better than dry cotton, which has essentially the conductivity of air. Any fabric which fails to saturate with water will conduct heat less efficiently. Cotton has about the same evaporative cooling capacity as other fabrics. The big problem with cotton is that it absorbs water, rather than wicking it to the surface efficiently. It's also abrasive and non-elastic.
U. Reischl et al./ Journal of Fiber Bioengineering and Informatics 9:4 (2016)237–245.
U. Reischl et al./ Journal of Fiber Bioengineering and Informatics 9:4 (2016)237–245.
07-29-22, 08:06 AM
#37
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Disclosure: I am a student of the thermal sciences.
Evaporative heat transfer occurs whether the air temperature is above or below skin temperature. Good thing, too. Otherwise, we would all die when the air temperature went above 100F.
The energy released when water evaporates is called the Latent Heat of Evaporation. Water's latent heat is 2256 kJ/kg, which is a big number, and it shows how powerful sweating can be. Every ml of evaporated sweat carries away over 2 kJ of energy. Enough to cool 1 liter of water by about 0.5C.
Not really, the cooling effect of a wet shirt is entirely through evaporation (not the transient transfer of heat from hot air to cooler liquid water). A wet shirt is effective because its surface is wet, allowing evaporation to continue without interruption.
The energy released when water evaporates is called the Latent Heat of Evaporation. Water's latent heat is 2256 kJ/kg, which is a big number, and it shows how powerful sweating can be. Every ml of evaporated sweat carries away over 2 kJ of energy. Enough to cool 1 liter of water by about 0.5C.
Not really, the cooling effect of a wet shirt is entirely through evaporation (not the transient transfer of heat from hot air to cooler liquid water). A wet shirt is effective because its surface is wet, allowing evaporation to continue without interruption.
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07-29-22, 08:32 AM
#38
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Thanks for science -ing that out; my understanding of the evaporative mechanism is based on anecdotal experience and freshman physics a quarter -century ago.
All I can add is that wet cotton ( whether water or sweat) is that absolute worst thing to wear if you have to do any kind of athletic activity
All I can add is that wet cotton ( whether water or sweat) is that absolute worst thing to wear if you have to do any kind of athletic activity
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