The Optum rider won the time trial championship in June, then took the sprints classification at the Parx Philly Cycling Classic. He hit the podium in several mid-west regional races before helping teammate Mike Friedman claim the overall win at the Nature Valley Grand Prix. He took a small break before starting things up again at Cascade, where he crashed out of the breakaway on the final day.
"It was just one of those dumb things," Zirbel said of the crash. "Another rider was actually trying to hand me something - ice or something. I looked over to try and grab it just as someone was slowing down in front of me. So it was just overlapped wheels, and I landed wrong - just enough to break [the collarbone] slightly."
Zirbel said the bones were not displaced and healed relatively quickly, allowing him to ride outside within a week and to put 100 percent focus on the race in Colorado, where he now lives.
"I feel really good, but I've raced like seven times in the last two months," Zirbel said. "So I feel like I'm a little under-raced, but I really just feel good. And it's not often as a pro where you get to focus 100 percent on a race for two or three weeks, so that's been nice."
Zirbel said the Optum team is hoping to make it onto the podium, citing several opportunities for team sprinter Ken Hanson and other opportunities that will present themselves for breakaways. The rider known for his size and power output said he is also looking forward to wearing his stars-and-stripes kit during the stage 5 time trial in Vail, which gains about 1,500 feet (457 meters) of elevation in just 16.1km.
"The time trial in Vail is not great for me, but it's not terrible," he said. "I'm going to go hard and see what I can do there. I'm climbing well for me. I'm not sure what that translates to here, but I'll try my best. It's going to be great, and it's going to be cool atmosphere to have a lot of friends up there on Vail Pass, too."
Beyond Colorado, Zirbel is looking forward to representing Optum at the world team time trial championships in Florence, Italy in September. This season will be the second consecutive year Optum has been invited to the event. And as reigning national champion, Zirbel has a shot to represent the US during the individual time trial as well.
"We have a really strong team for the team time trial, and the course looks good for us, so I'm really excited about that," he said. "And there's still potential for me to go as an individual, but we probably won't hear anything about that for awhile. But at the very least, going there with the Optum team is going to be great."