Nicolas Vouilloz, the most successful downhill racer in the seven years of world mountain bike titles, won the men's senior downhill for the second consecutive year after previously winning the junior category for two years.
He was joined on the winner's dias by compatriots Anne-Caroline Chausson and Nolvenn Le Caer, the senior and junior women's champions.
Cedric Gracia, expected to seal a clean sweep for France, had to be content with second place in win the men's junior final behind Swiss Andy Bueler.
Vouilloz, 20, from Nice, won the elite men's downhill event in a time of four minutes 54.79 seconds. He was the 18th rider off in the final and was not confident his time would be good enough.
American Shaun Palmer, a four-time world snowboarding champion, finished just 0.15 of a second outside the Frenchman's time in second place. Dutchman Bas De Bever was third, 0.33 seconds adrift.
"Winning this year makes me very happy because last year, while it was great, a rider in the junior race beat my time. This year I really know I am the fastest in the world," said Vouilloz.
"My run went well. I made a few mistakes at the top. Although, the (grassed) end is very long. There was a lot of pedalling and my legs were really sore."
The women's senior final also saw a tight finish with Chausson, last year's world junior champion, beating the defending senior champion Leigh Donovan of the United States by 0.18 of a second.
Le Caer, a silver medallist last year, had a more comfortable winning margin in the women's junior downhill final finishing 35.74 seconds ahead of Swiss Sari Jorgensen with Sabrina Jonnier of France third.
In the men's junior final, Bueler saw off top seeded Gracia by 2.18 seconds with another Frenchman Maxime Gardella taking the bronze medal 3.46 seconds down.
The cross-country finals for senior elite men and women will be held Sunday.
1. Anne-Caroline Chausson (Fra) 5.27.58 2. Leigh Donovan (USA) 0.18 3. Missy Giove (USA) 3.79 4. Giovanna Bonazzi (Ita) 11.79 5. Kim Sonier (USA) 12.85 6. Mercedes Gonzalez (Spa) 15.15 7. Mikki Douglass (USA) 19.65 8. Marla Streb (USA) 21.87 9. Elke Brutsaert (USA) 21.98 10. Rita Burgi (Swi) 23.59 11. Katja Repo (Fin) 27.28 12. Carole Grange (Fra) 29.75 13. Malin Lindgren (Swe) 34.83 14. Katrina Miller (Aus) 36.46 15. Tara Llanes (USA) 38.13
1. Nolvenn Le Caer (Fra) 7.45.83 2. Sari Jorgensen (Swi) 35.74 3. Sabrina Jonnier (Fra) 38.01 4. Hiroko Inomata (Jpn) 2.11.06 5. Sarah Stieger (Swi) 2.25.96 6. Melissa Miller (USA) 2.27.85 7. Tabiatha Fitzgerald (Aus) 3.28.62 8. Miriam Blas (Spa) 3.35.13 9. Helena Kurandova (Cze) 5.23.61 10. Tracy Brown (Nzl) 5.42.76
1. Nicolas Vouilloz (Fra) 4.54.79 2. Shaun Palmer (USA) 0.15 3. Bas De Bever (Ned) 0.33 4. Eric Carter (USA) 1.71 5. Mike King (USA) 2.43 6. Scott Sharples (Aus) 2.44 7. Marcus Klausmann (Ger) 3.89 8. Jurgen Beneke (Ger) 3.97 9. Sean McCarroll (Aus) 4.14 10. Tomas Misser (Spa) 4.18 11. Michel Joseph (Swi) 4.57 12. Michael Ronning (Aus) 4.72 13. Brian Lopes (USA) 4.80 14. Dave Cullinan (USA) 4.86 15. Steve Peat (Gbr) 4.95
1. Andy Bueler (Swi) 5.00.39 2. Cedric Gracia (Fra) 2.18 3. Maxime Gardella (Fra) 3.46 4. Tobias Westman (Swe) 3.57 5. Jan Lundman (Swe) 7.73 6. Rich Houseman (USA) 9.14 7. Eric Anselmo (Ita) 9.66 8. Jess Swiggers (USA) 15.15 9. Colin Bailey (USA) 15.36 10. Thomas Ryser (Swi) 16.70