For those who spend their summers ramping up their fitness with off-road running, it’s often easier to motivate when there’s a goal to shoot for. Now that the snow is slowly beginning to disappear (we think) from the mountains, here are a few spectacularly beautiful—and challenging—trail races that warrant an ‘X’ on your calendar.

Audi Power of Four Trail Run

When: July 13
Where: Aspen/Snowmass
You might as well start big with this one, especially if you can handle the 50K race, which takes you from the base of Aspen Mountain all the way across Aspen Highlands, Buttermilk, and Snowmass, through streams and up and down narrow singletrack, ascending (and descending) almost 10,000 vertical feet. If that sounds a little too challenging, you can instead tackle the 25K race from the base of Buttermilk to Snowmass Village. It’s a bit more gradual and only climbs around 3,500 vertical feet. Still too much? Maybe the 10K is more your jam—especially since it’s all downhill from the top of Snowmass to the base area.

Wild West Relay

When: August 2–3
Where: Fort Collins to Steamboat Springs
Yes, this is another giant undertaking—200 miles to be exact—but it’s a worthy challenge for you and 11 of your runner friends. This overnight event starts north of Fort Collins and takes you on paved and dirt roads, through several national forests, and on the shoulder of a couple of highways, even dipping into Wyoming, before heading up and over Rabbit Ears Pass (which comes with its own time trial, notably called “Get Your Ass Over the Pass”) to Steamboat Springs, where a beer garden and dip in the Yampa River await. Registration is limited to 150 teams and closes July 19.

Georgetown to Idaho Springs Half Marathon

When: August 10
Where: Georgetown to Idaho Springs
If a half marathon has been on your bucket list for a while, this one—now in its 41st year—is ideal for a newbie. Why? It’s downhill the whole way. The course takes you from Georgetown on dirt and paved roads alongside Clear Creek (don’t worry, it’s not on I-70), dropping 1,000 vertical feet to Idaho Springs, where you can celebrate your finish with your fellow runners on the Clear Creek football field, surrounded by stunning scenery.

Flaming Foliage Relay

When: September 6–7
Where: Idaho Springs to Buena Vista
This may just be the most rewarding leaf-peeping experience you’ll ever have. This 165-mile overnight course takes you through all the places where Colorado’s fall foliage is on full display: Guanella, Georgia, and Fremont Passes. But while the views are stunning, the course is no joke. You’ll traverse paved and dirt roads plus plenty of singletrack through Breckenridge, Frisco, and Leadville before landing in Buena Vista, gaining (and losing) nearly 17,000 vertical feet along the way. Sound tough? Your team of 10 can handle it. Registration is limited to 150 teams and closes on August 16.


When: September 7
Where: Nederland
This running event has been happening for more than 30 years and still maintains its friendly, grassroots vibe. While you can choose a 10K or 5K, too, the half marathon is enticing. It’s an out-and-back course to and from Old Town Nederland, mostly on dirt roads and singletrack. It’s not incredibly steep, either. The entire route gains just over 1,000 vertical feet, making it an approachable run even for first-time marathoners.

Boulder Backroads Half Marathon/10K

When: September 28
Where: Boulder
Now in its 19th year, this half marathon is still one of Colorado’s most popular off-road races. Both the half marathon and 10K start and finish at Boulder Reservoir and take you on relatively flat terrain comprised of dirt and paved roads. Expect lots of support along the way—maybe even some bagpipes—plus beer from local favorite Avery Brewing Co. and local eats at the finish line. Registration closes September 27.

Bear Chase Trail Race

When: September 28–29
Where: Lakewood
You probably didn’t know there was an ultra race right here in Denver’s backyard. This collection of endurance events at Bear Creek Lake Park in Lakewood includes 10K, half marathon, 50K, and 50-mile and 100K races, all on mostly dirt trails and including at least one splash through Bear Creek. Anyone considering a dabble in ultramarathons should give it a shot, since it’s not nearly as technical (or steep) as other long-distance trail runs out there.