Mosaic’s Flagstaff Week, a Boulder cycling tradition now in its 12th year, is upon us. Are you ready? Doesn’t matter. Flagstaff Week isn’t about being ready. It’s about way more than that. It’s a hard, good time that’s best explained by its creator, Mosaic Founder and CEO Aaron Barcheck, in his own words:
The Setup
For me, the word adventure usually suggests an epic voyage—likely a trip far away to a place I’ve never been, with the challenge of riding in a way I’ve never done before. This spirit is what defines many of us as cyclists and keeps us coming back for more. There’s always a new experience to explore, something to plan, something to work toward.

But it’s easy to forget that some of the best adventures are the ones we experience close to home—the ones we return to every season. With that said, today we explore a time-honored tradition at Mosaic: Flagstaff Week, an adventure we look forward to every year, right in our backyard of Boulder, Colorado.
The Route
The Flagstaff Road climb is Boulder’s crown jewel of cycling routes—and worthy of the title for many reasons. At just over five miles and two thousand feet of vertical gain, Flagstaff is a challenging yet accessible ride. Centrally located, it’s never more than a quick spin across town to reach the base.

The climb kicks up quickly, offering expansive views of the city and surrounding areas. As you ascend, the terrain constantly shifts—grindy 10% pitches give way to mellow switchbacks, which then transition into steeper switchbacks, broken up only by brief moments of recovery. But don’t be fooled. The first half’s undulating climb and sweeping vistas lead to a second half that hits with full force.

Just before the summit lies a stretch affectionately (and accurately) known as “The Wall”—an 18% grade that tests your legs and your resolve. In conquering one of the Front Range’s most unrelenting two-mile stretches, you’re rewarded with views of the Continental Divide and a finale featuring two of the most photogenic switchbacks in the region—famous across countless Instagram feeds.

From the summit, you’ll find yourself surrounded by a remote, forested mountain top, a stark contrast to the sweeping view back toward Boulder. From up here, the city looks like a sprawling sea of civilization, fading into Eastern Colorado and the curve of the earth.
At the top, the iconic mailboxes mark the finish line and the end of another successful Flagstaff lap. From here, you have a choice: continue west into some of Boulder’s most beloved loops, or flip it and descend.

The climb’s diverse terrain becomes a fast, technical, and exhilarating ride back down. With repetition, this descent becomes second nature—you memorize every turn, every crack in the pavement, every patch of sand. Confidence grows. Wash, rinse, repeat.
So. Much. Fun.

The Origin Story
This year, Flagstaff Week will kick off for its twelfth year—thirteenth if you count the COVID season when we couldn’t gather.
In Mosaic’s early, bootstrapped days, the Flagstaff climb was my escape from the grind of launching a business. I was working two jobs, had little time to ride, and felt more out of shape—and more disconnected from the joy of riding—each season. Something had to change.
So I did what I always do: I doubled down. I had the idea to wake up even earlier to ride Flagstaff every morning for a week before heading to The Pro’s Closet, followed by a second shift at Mosaic. I hoped this would kick off the summer season and snap me back into form—physically and mentally. To keep myself accountable, I invited a few friends for a little morning peer pressure.
Year one, we had five riders total: my wife Liz and three friends. Riding Flag five days in a row felt like a novelty—maybe even a big deal. We gave it a shot and, despite being totally spent by the end, we completed every day.
Year two, we knew we had to do it again. This time, maybe ten friends joined. I gave it a name—Flagstaff Week—because, well, everything needs a brand in my world.
Around year three, the now-famous Flagstaff Week punch card was born. I thought it’d be a fun way to mark each day’s ride, so I placed a hole punch at the mailboxes and handed cards out to the 30 or so attendees. The card became more than a keepsake—it was a record of each ascent, a motivator, and a reminder that another Flagstaff Week was always just around the corner.
Now, on rides people ask me “When is Flagstaff Week this year?” more often than they ask how I’m doing. There have even been counterfeit punch cards made! I guess imitation really is the sincerest form of flattery.

As the years went on and more riders joined in, my little underground event grew beyond me. It became something personal to so many: a chance to push for a PR, a five-day streak of a tough but rewarding climb, or—for some—a first summit, donuts and laughter shared with friends at the top.
For me, it’s still what it was from the beginning: a way to kick off summer by reconnecting with the people and the sport I love.
No qualifiers, no licenses (okay there is a waiver form) no entry fees. Just come and ride. Details below and we hope to see you on the climb.
The Details – 2025 Mosaic Flagstaff Week: June 2-6
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- The Mission: Complete a minimum of one Flagstaff Climb (to the mailboxes!!) per day, five days in a row. At the top, you’ll find a punch chained to the mailboxes. Punch your card, and then head to Cassiopeia for a coffee & daily special on waffles, lattes and more!
- The Punch Card Pickup: Riders can pick up their 2025 Mosaic Flagstaff Week Cards at Cassiopeia anytime starting on Wednesday, May 28th.
- The Waivers: must be signed to pick up your 2025 Mosaic Flagstaff Week punchcard. Download one.
- The Swag: If you get all 5 punches, you might get some sick prizes, posters, etc…
- The Daily Schedule:
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- The Mosaic crew will be rolling from Cassiopeia @ 6:45am each day, returning for a coffee after the climb. You are not required to ride with us. We would encourage people to ride the climb whenever suits them best, with whoever they want, just get the punch at the top and have a damn good time.
- Wednesday – Women’s Ride led by Cassiopeia staff.
- Friday – social hangout at Cassiopeia from 8:45 to roughly 10:00am.
See you out there, maybe more than once!
-Aaron
