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-   -   Hot Weather Base-Layer & Convection Effect (http://www.horizonsunlimited.com/hubb/the-hubb-pub/hot-weather-base-layer-convection-64676)

L'ilDRling 7 Jun 2012 17:10

Hot Weather Base-Layer & Convection Effect
Hi All,

I have perused the thread pertaining to hot weather base layers but haven't been able to find anyone really talking about the convection effect. Basically, the idea is that in extremely hot, dry weather you can basically cook yourself due to loss of moisture.

I was thinking, in anticipation of doing some desert-like riding on a RTW trip next year, that finding some sort of base-layer or top layer to help combat this would be a good thing. I'm trying to find pointers to find some sort of balance between overheating, and completely drying out.

Does anyone have any experience with the convection effect? Or have recommendations for some sort base or top layer?


BlackDogZulu 11 Jul 2012 06:10

I doubt if you would 'cook' as such - meat doesn't begin to cook until well over 100 deg. But you can dehydrate massively in hot dry conditions, and that can be life-threatening. There is no way round the fact that the body needs to evaporate moisture from the skin to cool itself, so taking in plenty of fluids is essential. With adequate fluid intake, the body can cope with a surprising amount of heat.

Reduce heat from radiation (i.e. solar) by wearing light colours and keeping the skin covered, and keep the evaporation going by wearing loose clothing. A wicking base layer and a top layer with plenty of ventilation would perhaps be the best. Bear in mind that I have no experience of long miles in very hot conditions - the above is based on simple physiology - and I stand to be corrected by someone with greater experience. But no-one else had replied, so I thought I would chip in :)

markharf 11 Jul 2012 07:36

Use of the word "convection" in the OP's sense is confusing. Convection is one of the ways heat transfers, e.g., by air or water movement. Other ways include radiation and conduction, which don't involve movement of air or water. So when you try to "combat this," what are you trying to combat? Something called a "convection effect?" What's that?

I don't know what "convection" has to do with "cooking yourself" either. What's "cooking yourself?" Getting overheated? Getting dehydrated? These are separate, but intertwined, phenomenon. Or do you mean actually sizzling and turning dark brown internally, like a juicy steak on the grill?

And I don't understand the need for a "balance between overheating and completely drying out," as if these are opposite ends of the spectrum and you need to make sure you don't get too much of one or you won't get enough of the other.

That's why I didn't answer the OP: I don't really know what you're asking. On the other hand, I have some sense of how to keep cool while riding motorcycles in hot, dry climates, and #1 is pretty much spot on: reflect sunlight and provide air circulation for wicking sweat. Evaporation of sweat cools you.

Other factors worth considering: riding when it's not so hot and the sun not so direct, i.e., early and late in the day. Avoiding all exercise when overheated--this means no getting stuck in the sand or changing flat tires. Air movement helps, so try not to get stuck in any traffic jams (or road construction; the hottest I've yet seen on a bike was well over 50C/122F at a construction roadblock in full sun in Brazil). And yes, you need vast supplies of water and electrolytes to stay hydrated--6 or 8 liters per day is a good starting point, but more won't hurt.

The other key factor, not yet mentioned, is wetting your clothing constantly--and wearing clothing chosen to absorb lots of water, then release it while you ride to provide evaporative cooling. It's like sweating, except even better. Do this a lot, even with warm water, and you can ride in reasonable comfort in very hot weather....until that first traffic light, construction zone, or soft-sand crash.

Hope this is helpful.


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