Hi,
A little late, maybe, but I wanted to throw in my tuppence worth, specifically in response to Alan Hopkins's queries.

I travelled Lagos, Nigeria to Dublin, Ireland in July/August 2002, crossing the Sahara along the Western route.

It was very, very hot during the day and very hot during the night. I didn't experience any plummeting temperatures during the night, even with clear skies in the desert. Most nights I lay in my tent with just a sleeping bag liner over me, and it was wet through in the morning!

On the bike, I wore a Dainese Safety Jacket (Arnie mesh vests, as Alan calls them) and Fox Pivot Knee protectors. (Didn't fancy having myself reconstructed in an African hospital. Riding without protection isn't worth it--that's only my opinion though. Make up your own mind how much you're worth intact.)

Over that I had cordura jacket and trousers (fleece linings removed): Rev-It Multi-Pass jacket (c. EUR500) and Rev-It ??? trousers. (c. EUR180). Expensive I know, but they are EXCELLENT. I'd definitely buy their stuff again. To be honest they were a bit heavy duty for Africa but I bought with riding in Ireland (cold, wet) when I returned in mind too. A little compromise there.

They weren't unbearably hot, once you were riding along. Stopping at customs, police checkpoints, etc. was when you felt you were cooking. Still, I think with height-of-summer temperatures, you'll feel hot in anything.

For slow-speed, off-road sections, where I wasn't moving quickly enough to get a cooling breeze, I took off the cordura jacket and just had the safety jacket on. Watch for sunburn on the back of the neck though. A wet t-shirt, folded and stuffed under the shoulders of the safety jacket, covering my neck, did the trick.

The safety jacket did get a bit smelly after 4-5 days of camping and no showers. I usually washed it in the shower at the next opportunity and hung it out to dry. No problems there.

My travelling buddy had the same safety jacket and knee protectors, but instead of cordura, had a tough twill/canvas pair of trousers. I think he got them from Hein Gericke. His jacket was lightweight, MX style with some zipper vents for improved ventilation. He was hot too though.

We both dehydrated several times each. The only thing to do is stop and get in the shade and drink loads of water. Take some Gatorade too, or bring some rehydration salts like Electrolate (see your pharmacist: standard rehydration salts if you have severe diarrhoea).

THE best piece of kit we had with us was a three-litre Camelbak sitting under our jackets. It meant we could take a sip every couple of minutes without having to stop, get off the bikes, etc. I can't recommend this enough. We'd drink a full Camelbak on an average day, two on the really hot days in the desert (45ºC in the shade!), and like I said, we still managed to dehydrate!! It's well worth the money. I still use mine, cycling, running, skiing, etc. My EUR500 jacket also earns its keep on the snow slopes too!

Hope this helps. By the way, I'd be interested to hear people's opinions of Rev-It gear. I am well impressed.

See ya later!