Riders Geoff Aaron and Kevin Rookstool have had their ups and downs through the first four races of the season, but both are confident the second half will be better.“This year has been rough trying to get some momentum built up,” said Aaron, who finished 14th last time out. “I’ve been battling a shoulder injury which has led to a spiral effect when it comes to the races.“To keep my shoulder healing, I’ve kept the wear and tear down by not training as much. But when you don’t train as much, you aren’t as sharp when it comes time to race.”Aaron is in 12th place in the series standings, 13 points out of a spot in the Top 10.“I’m riding in my hometown this weekend and it’s got me pretty stoked,” Aaron said. “Maybe a little hometown karma will be what I need to get going.”Rookstool is looking to rebound from a 12th-place finish in Ontario, Calif., last month.“Most of the other racing I do has wrapped up for the year,” he said. “This really gives me a chance to focus on riding Endurocross and make a big push here in the last half of the season.”Rookstool currently sits seventh in the Endurcocross points and has a legitimate shot at making a move into the top five before the season ends. He is one point out of sixth and 13 behind fifth-place Colton Haaker.“This is an unpredictable sport,” said Rookstool, who had the team’s only podium finish this year in Sacramento, Calif. “It’s easy to be king one week and a peasant the next. With only an eight race schedule, the points can get jumbled around a bunch every week. We just need be in position to be the king when the timing is right.”Practice for Saturday’s GEICO Motorcycle AMA Endurocross event gets under way at 9 a.m. MDT. Qualifying starts at 11 a.m. with an autograph session starting at 6 p.m. with opening ceremonies at 7:30 p.m.