@Dan, if the America's Great Basin are too hot in summer, i imagine the regions around is the same (Utha, Arizona, Colorado..)
So what is the adequate period to visit this area ?
Julien,
The Great Basin is comprised of separately designated deserts and smaller basins but is generally regarded as a whole with somewhat ill-defined boundaries. The Great Basin is considered to be a "cold" desert because it can rain or snow there and when it is wet, it can quickly become impassable -- like trying to cycle or walk in pudding. There are hot springs which can be boiling and there is only a little drinkable water from springs, seeps, and areas where cattle graze. The problem is not so much contamination as excessive alkalinity, so I take pH test strips with me to check before drinking to avoid chemical burns inside.
The alkali dust of the playa/dry lake beds is very corrosive and attacks mucous membranes around the nose, lips, and mouth and causes a malady called "playa foot" where the skin can harden and split open from the extreme drying caused by prolonged exposure or walking barefoot or in sandals. The playa dust can and does blow in the wind and there are sometimes dust storms. It is highly abrasive and tends to collect in small crevices and on chains. I floss my chain with a mascara brush each night and freshly re-oil it before I go to sleep.
Plus considerably more of the same.
Translation: For masochists only. Stay out!
Seriously, while I read the whole of this exceedingly expert screed with the greatest interest, when a region requires so much precautionary advice, such dangerous places make a hazardous introduction to a fantastically diverse continent, with plenty of alternative interest wherever you go.
For your first North American tour, choose an easier route. You'll want to keep going back, and eventually you will be ready to take on Dan's beloved playa.
It's natural to think of an American odyssey as running across the grand width of the US or Canada or even Mexico for those with iron nerves, or west to east, but, depending on what time of the year you start, a vertical tour might make a lot more sense. If you start in the summer in Canada and ride south, ending in Florida in the winter, the good weather will travel with you; the same applies to starting in Alaska and riding south besides the Pacific Ocean. Or you can start in the winter in the South and travel north to reach Canada in the summer or even the earlier part of the autumn, which is beautiful in the 13 original American states and, of course in Canada. Ditto for starting in Southern California and riding north through the Pacific Northwest to Canada and perhaps even Alaska as far as Juneau, though careful consideration of the likely weather would be required. You needn't of course do these "vertical" roads only up the coast. You could choose another theme, like the canals which stretch for instance from cities like Chicago on the Northern lakes all the way to the sea in Florida.
Good luck, and don't forget to send plenty of photographs.
Regarding bug repellants, a friend who was brought up in Africa told me that chewing two cloves of raw garlic per day was very effective at repelling mosquitoes.
Africa (like anywhere, really) is notorious for folk remedies that don’t actually work; overlanders are exposed to a lot as they cross the continent. But malaria is no joke and has claimed the lives of members of our community, and doctors specialized in the region do recommend repellent with DEET.
When cycling in mosquito country, I recommend covering up with an expedition shirt over a breathable merino-wool microweight base layer, and expedition trousers (my favourite is the Fjällräven Abisko). Mosquitos can’t bite through the polycotton fabric that such clothes are normally made from.
I don't know if two (!) cloves of garlic will repulse mosquitoes but it will certainly cut short interchanges with humans. What does work as a mosquito repellent is a couple of gin and tonics, because gin, just like garlic, exits through your skin. But this was originally Indian folk wisdom, imported to Africa with the British.