Steamboat Springs Tonight's Town Challenge Mountain Bike race will be a key factor in determining the final winners of the series.
Many top-place competitors coming into the seventh race of the eight-part series are within two to three points, race coordinator Gretchen Sehler said.
One of the closest races is in the men's 19 to 29 age division. Ethan Johnson leads with 100 points, but Spencer Sator follows with 99.
Because bikers can still throw away one of their eight races, the seventh race can still be used to gain the lead.
"With one throw away race, some of those guys are leading," Sehler said. "Sator hasn't thrown away his race at this point."
Another close race will be in the women's thirty and over novice group. Cindy Hill is in the lead with 84 points, Lisa Famagliette follows with 80 and Ellen Stein is in third with 77 points.
The multi-lap course will begin at the base of Thunderhead and take bikers around the 3-mile course to the top of Burgess Creek Road.
Expert men will do four laps, expert women and novice men will do three laps, and novice women will do two laps. Each lap has an elevation gain of over 700 feet.
Because of the concentrated elevation climb and descent, the course's most technical part is the downhill slope.
The first race is at 5:59 p.m.