The USA Cycling Mountain Bike National Championships, hosted by Granby Ranch, rolls today, July 14, and continues through July 18.The race brings together the best competitive athletes in cross-country, downhill, Super D, 4-cross and short track. Races will feature more than 2,000 national-caliber mountain bikers, competing at the SolVista Bike Park. Some 5,000-7,000 spectators are expected to attend. Viewing areas will be set up around the course, including at the site of the 4-cross races, which are some of the most exciting competitions from a spectator's standpoint.Taking place under the lights Saturday, July 17, 4-cross is similar to the boardercross snowboard event. Four bikes line up and duke it out, simply trying to be the first to get down the hill.During the junior class downhill races, SolVista Bike Park Manager Matt Thompson said to watch for up and coming local athletes Kellen Lutz, 14, and Sawyer Cousineau, 12. In the adult classes, keep an eye out for professional rider Aaron Gwin of Morongo Valley, Calif., who is sponsored by Yeti Cycle cycles of Golden, Thompson said. Gwin broke into the international World Cup scene after only 8 months of riding downhill and since 2008 has stood on three World Cup podiums. Luke Strobel (Issaquah, Wash.), Duncan Riffle (Santa Barbara, Calif.) Mitch Ropelato (Ogden, Utah) and Joey Schusler (Boulder) are expected to lead the men's field in the gravity events, while the women's contests will see some strong rides from racers like world championship medalists Melissa Buhl (Chandler, Ariz.), Jill Kintner (Seattle, Wash.) and Kathy Pruitt (Santa Cruz, Calif.).Several viewing platforms will be set up to watch the downhill races. Spectators at the base will also be able to catch the last 30 seconds of action, Thomspon said. Most of the events, in fact, will be visible from the balcony at the base area. "We built these tracks for the nationals," Thompson said. "It's important for us if we're going to showcase Granby Ranch to make it fun to watch."The cross-country races should also be easy for spectators to watch, Thompson said. The course will create a clover-leaf pattern centering on the SolVista base area. Fraser Valley resident Keith Sanders, the returning national champion in his age group, will be one to watch, Thompson added.Husband and wife pro-duo, Jeremy Horgan-Kobelski and Heather Irmiger, both of Boulder, will look to defend their cross-country titles from last year.Other professional endurance specialists to be on the lookout for over the weekend include Adam Craig (Bend, Ore.), Todd Wells (Durango), Ryan Trebon (Bend) and Sam Schultz (Missoula, Mont.) who recently scored his first national-level win. In the women's contest, Irmiger can expect some tough competition from riders like Georgia Gould (Fort Collins), Lea Davison (Jericho, Vt.), Willow Koerber (Asheville, N.C.) and Mary McConneloug (Chilmark, Mass.).All events are free to the spectators. - Reid Armstrong can be reached at 970-887-3334 ext. 19610 or firstname.lastname@example.org.