Why is it that France can do so well in mountain biking but is nowhere on the road? With a lot less money in MTB, there has to be a lot less testing.
I always felt that one of the main reasons the Americans faded away from the top of the MTB scene in the early and mid 90s was because of doping entering the sport.
Perhaps it is because the French are actually doing less drugs and there are less drugs in MTB racing?
The French have had one of the stricter anti-doping regimes in men's road racing for a few years, which could be one of the reasons why they haven't done so well on the road.
And like you say, there's stuff all money in MTB - at least compared to the road. That means that there's less ability for riders to engage in the sort of doping practises that roadies do ... as well as a lot less motivation to do so. I mean, if you're not in line for a multi-million euro contract, are you really going to spend a big proportion of your hard earned on PEDs?
Also, don't forget that there are a lot less participants in top flight MTB racing and a much smaller calendar. Look at the start lists for the world cup XC races and you'll see the same 30 or so riders turning up each time, with the remainder of the fields made up by wild cards. So, if you've got one or two North Americans in that sort of field, the proportion is actually probably better than what you're seeing on the road.
I think also that MTB racing's popularity in Europe has been a lot more consistent than it has in a number of other countries. XC racing in a lot of the world has suffered at the hands of DH and 4-X, but not in Europe. There are heaps of great races over there that people in the rest of the world don't know about. So, if you've got a heap of races to choose from with a good depth of field, of course you're going to generate a higher proportion of top riders. Put another way - I think that North American's got caught napping after dominating the early days of the sport and are now playing a big game of catch up ....
Also by talking about a "French domination" you're actually slighting a number of top flight riders who are/have been still mixing it seriously at the front of the fields - eg., Sauser, Paulissen, Kessiakoff (who I know is now a roadie ), Naef, Vogel, Hermida ... check out their results and you'll see that it's definitely not a one way street for the French ...
Then again, if you bear in mind that some of the best women XC racers in the world at the moment are all Quebecoise, it may just be that there is something in the French psyche that suits the sport ...