Might as well throw in my two cents since I enjoy this topic. Living in Las Vegas and riding daily, year-round, including multiple trips through Death Valley in all seasons means that hot weather riding is routine business for me.
There is one huge fallacy about hot weather riding - that is the idea that you need to keep cool. You only need to keep warm. After all, your body wants to be about 98 degrees (F). Being warm requires very little energy, is not stressful, and can be tolerated indefinitely.
Being warm still means being cooler than the hot condition you're in, but nowhere near the differential between hot and cool. The differential between hot and warm is much easier to achieve and maintain over a long period of time. Cruising on a motorcycle is a low energy activity, so you shouldn't be working up a sweat even in warm temps.
For me, it's counter-productive to put myself through heating and cooling cycles from extremes between being iced and wind burned. It's much less stressful for me to maintain a constant, albeit warm temp than to fluctuate.
Let's talk about wind burn. I pity the poor fools I see riding in shorts and t-shirts on really hot days. They're unprotected from ultraviolet, hot air, and ambient heat from the engine and road surface. Do this experiment. Take a hair dryer on high, hold it in your right hand and aim at your left arm (lefties can reverse) and see how long it takes to get uncomfortable. Please don't hurt yourself. Then don a mesh jacket and try it again. You might get an extra minute. Then try it with your full protection jacket, cordura, leather, whatever you wear when you want maximum protection. I guarantee that you can stand the hair dryer treatment a lot longer when well covered.
We all know about wind chill, but it's less common to talk about the opposite effect - wind burn. At about 100 degrees F and above, the wind burn effect kicks in, making the exposure to hot air worse the faster you go. Hot air speed up is hotter than still air of the same original temperature. This is why I won't use mesh jackets in hot weather, above 95. Mesh doesn't provide enough protection from wind burn.
So after all that introduction and diatribe, what do I do in hot weather? I wear a light weight, full length, wicking base layer (I've found the Bilt Heat-Out gear from CycleGear to be cheap, effective, and surprisingly durable), cooling vest (the water-soaked type), and full textile riding suit (cordura jacket & pants). For longer trips (over one hour), I bring a dry bag with water for quick recharging. Most importantly, I close all the jacket vents, except for maybe a rear vent. I know that sounds counter-intuitive, but it does two important things. 1. Closed vents slow the rate of evaporation allowing the effect of the cooling vest to last longer. 2. It stabilizes the temperature. Yes it's warm, but being warm is comfortable and still better than being hot.
Finally, even though to some extent we're talking about wearing water, do not overlook the need to drink a lot of water! If you're out in the heat for a long time, the occasional electrolyte replacement (Gatorade) is a good idea too.
To recap, the morale of this story is - hot weather riding is all about staying warm, not cool.
Warmest regards,
Boondocker.
