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  1. #1
    eternalvoyage
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    How Much Sun, How Much Heat?

    The hottest deserts in the world are.... dangerous [[side note: where are the hottest ones, anyway? And what is the measure? All-time hottest temperatures? Hottest averages? Most days over 120? Other?]] [[Death Valley is pretty hot and dangerous, but so is the Namib and parts of the Sahara....and others....]].

    Where does one draw the line on exposure times, and modes of exposure?

    [[side note: I knew someone who had experienced sunstroke or overexposure to the sun when he was a young man. He still had residual problems and limitations, even many years later. He had to be much more careful with himself than otherwise.]]

    *******
    And what about humidity? I just reread an account of someone's bike journey through the Amazon basin. It was not as hot as many deserts, but it was much more humid. He drank up to 15 liters per day (mostly water).

    *******
    So I guess are two (at least) issues here.

    The first is sun exposure. How do you know when you've crossed the line?

    Or, how do you know when you are approaching that line?
    Last edited by Niles H.; 02-02-08 at 03:25 PM.

  2. #2
    eternalvoyage
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    I just came across this,

    I have family in the Western Sahara and visit them every year, although I haven't been in the summer yet.
    They don't sit around in the sun and if they go out in the day they cover up. Their clothes are loose, not fitted and although you think they would be hot the clothes make you feel cooler!
    The houses have been built well and inside it is cool, they don't need air-conditioning in their house. I have never had trouble sleeping because of the heat.
    They have a siesta at the hottest time of day.
    They don't eat 3 big meals a day, they eat about 5 small meals.
    There are more people out and about in the evening, when it is cooler.

    Why do Tuaregs (among others) dress like that? Wouldn't you think that all that cloth (however loose) would heat things up a bit??

    I've never seen a cyclist in Tuareg wear; but maybe it would make some kind of sense, at times at least?

    *******
    Five small meals?

    Why this, for desert heat??

  3. #3
    Long Distance Cyclist Machka's Avatar
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    I've done a recreational 200 km ride at about 48C (in Winnipeg area). And the first 400 kms of a 1200K (in California) in about the same type of heat. I was fine on those occasions, although I think I did start to feel it on the 400K. However, I DNF'd a century (first one of over 100 centuries I've ever DNF'd!) due to heat related issues when the temps were about 40C this past year (in central Alberta). I'm not as used to the heat as I used to be.

    And people should eat 5 smaller meals a day anyway, no matter what the temperature.

    Planning a ride across the Sahara??

  4. #4
    Has opinion, will express
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    Are you running a competition with someone to boost your posts on BFs, or something? Why the fascination with these heat issues? Are you compensating for winter over there?

    People work in the conditions you describe. I work in the Australian summer with not that much shade, in direct sunlight that with the atmospheric conditions create temps around 50 deg C. Pipeline welders work in similar temps but with additional protective clothing on.

    My appetitve dwindles in really warm and/or humid conditions. Check the material used in making the clothing you refer too... almost guaranteed it is light cotton. And it is an effective protection against UV radiation. And, I have said this many times on these forums -- cyclists tend to wear clothing that is too tight in both summer and winter, and that air is needed to help stabilise temps near the skin -- as well as to facilitate the cooling effect of evaporation of sweat.

    It comes down to management and acclimatisation. Take the Californian cyclists who whine when they have to put on arm and leg warmers when the temps drop to 80 deg F... and the Canadians who matter-of-course put on the wool and extra layers to ride when the temps drop to 0 deg F.

    I doubt there are too many Arabians who live in the deserts who regard their environment as dangerous because, as your second post points out, they have its management sussed out. And I doubt that there are too many Amazonian natives who regard their humid environments as uncomfortable because they, too, have worked out ways to do what they have to do. And the Europeans? Well, they take a siesta in the middle of the day when it is hottest.

    The sunlight isn't so much the issue. It's the effect it has on the air in particular, the land and the water. The issue for humans is the effect a narrow band of radiation has on the skin.
    Dream. Dare. Do.

  5. #5
    eternalvoyage
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    Those Californians have it easy -- what with all those wussy deserts with little old 134 temps.

    And their little 14K mountains in three different ranges, and those bitty mountain passes on the Markleeville Death Rides (qv)....

    And digging out their cushy cabins at Mammoth in forty feet of snow....

    With temps under forty below....

    Hollywood softies all.

    Nothin like what you Aussies have to deal with....

    *******
    One has toured in some deserts [not the cushiest], in dry heat , with plans to do more. Deserts have a certain fascination, for some. The heat and sun are a challenge. They are beautiful.

    http://youtube.com/watch?v=RBFm92AW7Fk

    And one also plans to return to some tropical areas.

    Heat, sun exposure, heat stroke, extreme loss of moisture, etc. are very real concerns in some of these areas, and are worth being clear about.

  6. #6
    Long Distance Cyclist Machka's Avatar
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    Quote Originally Posted by Niles H. View Post
    Those Californians have it easy -- what with all those wussy deserts with little old 134 temps.

    And their little 14K mountains in three different ranges, and those bitty mountain passes on the Markleeville Death Rides (qv)....

    And digging out their cushy cabins at Mammoth in forty feet of snow....

    With temps under forty below....

    Hollywood softies all.

    Nothin like what you Aussies have to deal with....
    Have you travelled much outside the California area? Doesn't sound like it. Sure California is hot (sometimes, not all the time, and not everywhere), but so are other parts of the world. Australia can get VERY hot for extended periods of time.
    http://www.bom.gov.au/cgi-bin/silo/temp_maps.cgi
    http://www.bom.gov.au/cgi-bin/silo/t...th&time=latest
    Even the Winnipeg area, here in Canada, hits the mid+40sC in the summer ... while being in the mid-40sC in the winter.

    It really does come down to management and acclimatisation.

    You do know that the area with the most extremes in weather in North America is North Dakota, right ... NOT California. North Dakotans (and Manitobans, just north of them) are probably the best at adaptations in all of North America.

    And since when has Califoria ever experienced -40C/F???? Was that during the last ice age??

  7. #7
    Professional Fuss-Budget Bacciagalupe's Avatar
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    Definitely sounds like Niles has some cabin fever.

    FYI humans acclimate to exercising in hot weather in a few weeks. If properly trained and acclimated, humans can exercise in ridiculous temperatures, as epitomized in the Badwater Ultramarathon -- a 135-mile run across Death Valley in 130+ degree weather. Obviously you need to be in top physical shape to consider such an event, let alone qualify for it.

    Otherwise, there is no hard and fast rule for "how much sun" and "how much exposure." If you expect to ride in extreme high temps, a) stay hydrated b) make sure you're getting electrolytes and c) learn to recognize the symptoms of heat stroke / heat exhaustion.

  8. #8
    Slowpoach
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    Quote Originally Posted by Niles H. View Post
    I just came across this,

    I have family in the Western Sahara and visit them every year, although I haven't been in the summer yet.
    They don't sit around in the sun and if they go out in the day they cover up. Their clothes are loose, not fitted and although you think they would be hot the clothes make you feel cooler!
    The houses have been built well and inside it is cool, they don't need air-conditioning in their house. I have never had trouble sleeping because of the heat.
    They have a siesta at the hottest time of day.
    They don't eat 3 big meals a day, they eat about 5 small meals.
    There are more people out and about in the evening, when it is cooler.

    Why do Tuaregs (among others) dress like that? Wouldn't you think that all that cloth (however loose) would heat things up a bit??

    I've never seen a cyclist in Tuareg wear; but maybe it would make some kind of sense, at times at least?

    *******
    Five small meals?

    Why this, for desert heat??
    1. Siesta, out and about in the evening.
    Obvious, you rest when it is hottest and do stuff when it is cool.
    This is the normal way of doing things in hot areas. Only countries colonised by cold, northern, dark England (eg. yours and mine) have a tradition of working through the hottest part of the day (mad dogs and Englishmen...) Everyone else (central America, Asia, Africa, Mediterranean, Pacific, Mediterranean, Middle East) has a siesta tradition.

    2. House.
    Desert = hot dry heat during the day and cold nights. With heavy bulky walls houses can absorb heat during the day, leaving the inside cooler than it would otherwise be. At night the heat is released so the inside is not as cold as it would otherwise be. This is called thermal lag and is a feature of high thermal mass but relatively uninsulated buildings. It is perfect for these conditions.

    3. Clothes.
    They need to keep the sun off, keep cool during the day, keep warm at night and protect from wind. The heat is dry heat, so evaporative cooling (sweating) works well as a cooling strategy. The loose cotton clothes keep the sun off but allow air to circulate, so evaporative cooling continues.

    4. Cycling in these sorts of clothes
    In Africa this is common. In Vietnam I saw some guys in loose white cotton slacks and shirts they had bought in India. I haven't been to India but all the movies and doccos show people in loose white cotton clothes.

    5. 5 small meals.
    No idea. Might be a cultural thing as not all hot countries do it that way. Certainly a hot hearty big evening meal is something I look forward to when it is cold, not when it is hot.

  9. #9
    Junior Member
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    If you come around here and and are caucasian, You will fry in the sun - Use sunscreen, or your skin will die. It's simple, cover up. Covering the skin, so the sun does not shine directly on it will also keep you cooler, loose fitting, light coloured, pure cotton is the best. It's also very effective to avoid travel for 3 hours in the middle of the day. Siesta's, or a spell in a pub from midday to 3 are great ideas.

    I draw the line at 40 degrees Celcius, but everybody is different.

    I agree, deserts are amazing places, but hard to carry enough water for.

  10. #10
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    black robes

    Black robes will supposedly keep you cooler. They are open at the bottom, and as the sun heats them up the air inside the robe rises, and cooler air comes in the bottom, so your skin is cooled by a constant convection current of moving air.

    This is all a sidebar in an old physics textbook. I'm not sure I beleive it, since another sidebar is all about how one of the authors shattered his teeth with liquid nitrogen while trying to demonstrate the lidenfrost effect...





    Quote Originally Posted by Niles H. View Post
    I just came across this,

    I have family in the Western Sahara and visit them every year, although I haven't been in the summer yet.
    They don't sit around in the sun and if they go out in the day they cover up. Their clothes are loose, not fitted and although you think they would be hot the clothes make you feel cooler!
    The houses have been built well and inside it is cool, they don't need air-conditioning in their house. I have never had trouble sleeping because of the heat.
    They have a siesta at the hottest time of day.
    They don't eat 3 big meals a day, they eat about 5 small meals.
    There are more people out and about in the evening, when it is cooler.

    Why do Tuaregs (among others) dress like that? Wouldn't you think that all that cloth (however loose) would heat things up a bit??

    I've never seen a cyclist in Tuareg wear; but maybe it would make some kind of sense, at times at least?

    *******
    Five small meals?

    Why this, for desert heat??

  11. #11
    Walmart bike rider gpsblake's Avatar
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    The one thing about California weather.... You can be in Los Angeles for example, go 40 miles west, and be in a total blizzard. Same with San Francisco, you can travel across the bay to Oakland........

    Also in real hot weather, just like cold weather, it's most important to keep your head temperature from the extremes. That's why in the desert, people wear hats or stuff to keep thier head from overheating.

    With many people, you can't drink enough to keep yourself hydrated in really hot weather, especially if you aren't used to it. You will simply sweat more than what your body can absorbe to replace it.

    The key is learn what heat-stroke and heat-exhaustion is and the signs/symtoms of it.. Headaches, nausea, weakness, etc... even a little bit means to stop and cool down. If you stop sweating in hot weather, you better get yourself cooled down real quick.

    For most people, usually best to avoid riding in super hot conditions unless you **REALLY** know what you are doing and are used to it.... get your miles in the morning.. rest at library or other place for a few others... then get more miles at dusk.....

  12. #12
    Slowpoach
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    Quote Originally Posted by Niles H. View Post
    So I guess are two (at least) issues here.

    The first is sun exposure. How do you know when you've crossed the line?

    Or, how do you know when you are approaching that line?
    It can be pretty difficult to tell when you go from being hot to being impaired.

    Things to look out for:
    - Concentrated urine (or not needing to go). Drink enough to keep it pale and flowing! (Nb. If you are sweating heaps, you need electrolyte replacement as well as water replacement).
    - Headache
    - Cramps
    - Feeling vague / disoriented / off balance

    Unfortunately it kind of creeps up on you and it's hard to tell the difference between being tired and being overheated and dehydrated. You need to be proactive, eg. hydration and resting when the temps start getting ridiculous.

    With the sun, just cover up. You don't notice sunburn until it has happened. Same with melanoma.

    Sunscreen protects against sunburn and against squamous cell and basal cell carcinomas, but it is not clear that it protects against melanoma. Shade/clothes, sunglasses etc. do, however.

  13. #13
    Long Distance Cyclist Machka's Avatar
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    Quote Originally Posted by jstava View Post
    If you come around here and and are caucasian, You will fry in the sun - Use sunscreen, or your skin will die. It's simple, cover up. Covering the skin, so the sun does not shine directly on it will also keep you cooler, loose fitting, light coloured, pure cotton is the best. It's also very effective to avoid travel for 3 hours in the middle of the day. Siesta's, or a spell in a pub from midday to 3 are great ideas.

    I draw the line at 40 degrees Celcius, but everybody is different.

    I agree, deserts are amazing places, but hard to carry enough water for.

    I'm caucasian, and when I went to Australia, I didn't use sunscreen unless the people around me insisted I did. I hate the stuff, so sticky and messy. I just went from quite pale to a very dark brown. Now, the first couple months I was there, it wasn't overly hot, so I wore more clothing on many days, so I probably built up my tan layer gradually. The last month was up in Queensland in December ... 40+ degrees most days, and very humid. It was great!!!


    My upcoming trip will be a bit more of a shock to the system, and I probably will use sunscreen (ick). I'm going from temps that were -40C last week, to whatever the temps in the Melbourne area will be. And haven't had a chance to fake bake or anything, so I'm as white as snow!

  14. #14
    Bike touring webrarian
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    Here is an article about knowing the rate you sweat so that you can hydrate appropriately. This is about triathletes but it would likely apply to bike tourists, as well. Here is the conclusion:

    Determination of sweat rate, which can be calculated by evaluating total fluid intake and weight loss during activity, should be a high priority for athletes looking to maximize performance and protect against serious injury and/or health consequences such as heat stroke.

    Electrolytes need to be added to fluids when training in heat and/or training duration extends beyond an hour. Most athletes require .5 to 1 liter of fluid per hour along with .5 to 1 gram of sodium during prolonged training to prevent the detriments associated with fluid and/or electrolyte imbalances.
    Ray
    Visit the on-line Bike Touring Archive at www.biketouringtips.com

  15. #15
    eternalvoyage
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    M,

    Thanks for the interesting replies. Truly. They do, however, reflect a few minor misconceptions (if I may say so in all friendship, good will and courtesy).

    And yes, I have seen much of rest of the world, outside California, on various continents. However, after all the travel, I happen to like the region of California and the West better than any other, anywhere. I am not alone in this. Dennis Coello is among the others who feel the same way.

    Also, thanks for the information about California weather.

    There are no deserts in the world that have recorded temperatures as high as Death Valley (with the single exception of one slightly higher recording in the Libyan desert). There are no deserts or other places (on this planet) -- including those in Libya and the rest of the Africa, and certainly in Australia and Canada -- that have as many consecutive days over 120.

    As far as going below minus forty, it's easy to look up.

    As far as the snowpacks go, forget about it.

    I just got back from a tour that was designed to take advantage of the invigorating conditions created by the recent blizzards. It was great to get out in it.

    The variety here is nothing short of astonishing, and simply far and away greater than most places in the world . And I love it.

    *******
    One would also be hard pressed to find anywhere in the world that has contributed as much in the last thirty years to cycling. Marin County alone probably surpasses anything most other countries have contributed. There is probably a wider variety of used and new bikes, and bike manufacturers than anywhere else.

    And there is SF -- everyone who has any love left loves that city above any other. (Okay, that's a good one, but it is a beautiful city, and much of the state has incredible riding opportunities. Where else can you ride through the tallest trees in the world [the Coast Redwoods], then ride over to visit one of the most beautiful mountains [Shasta], then cut over to Lassen and one of the most beautiful mountain ranges [the Sierras], visit incredible alpine lakes [including Tahoe], ride some of the most beautiful trails in the world [voted as such, in Sierra County, Downieville, and parts of the Tahoe Rim Trail], dip into the Eastern deserts and Nevada, enter an ancient and giant smoldering caldera, ride up and over one of the most beautiful mountain passes [Tioga], visit the most beautiful park with the highest concentration of major and beautiful waterfalls in the world [by far], visit the largest trees that are (and ever have been) on the planet [Sequoias] and camp among them, swing up into the high country and over to the most productive agricultural area in the world [the Central Valley], and continue on to the hottest place [Death Valley], ride over to the most freewheeling city [LV], see the only Joshua trees in existence, and then visit all that the Angelinos and San Diego have to offer [quickly], before dipping down into the two states of Baja California [which many of us do] for the deserts and ocean and remote wilderness areas, and the tropics, before taking in the best whale watching on the eastern side, in the Sea of Cortez, and then catching a cheap flight to our sister state [where many of us divide our time] to the west for more...............................)
    Last edited by Niles H.; 02-06-08 at 06:14 PM.

  16. #16
    eternalvoyage
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    Thanks to everyone else too.... There have been some great replies, and some of it has been right on-topic and to the point of the thread. Thank you.

    *******
    Any other other contributions are most welcomed as well.
    Last edited by Niles H.; 02-05-08 at 01:39 PM.

  17. #17
    rwp
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    Quote Originally Posted by Machka View Post
    I've done a recreational 200 km ride at about 48C (in Winnipeg area). And the first 400 kms of a 1200K (in California) in about the same type of heat. I was fine on those occasions, although I think I did start to feel it on the 400K.

    For the record, the highest recorded temperature in Canada was 46C at Midale and Yellow Grass, SK on July 5, 1937. Some sources say 45C but the descrepancy is no doubt due to conversion from Fehrenheit.

  18. #18
    Long Distance Cyclist Machka's Avatar
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    Quote Originally Posted by rwp View Post
    For the record, the highest recorded temperature in Canada was 46C at Midale and Yellow Grass, SK on July 5, 1937. Some sources say 45C but the descrepancy is no doubt due to conversion from Fehrenheit.

    Recorded temps are in-the-shade temps ... there isn't much shade when cycling through the middle of Manitoba. I went by my on-bike thermometer.

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