Stroke & Stride
2026-07-16, 2026-07-23, 2026-07-30, 2026-08-06 | Boulder Reservoir, 5275 Reservoir Road, Boulder, CO, 80301, United States
The Boulder Stroke & Stride offers Boulder area athletes a fun 1-lap 750 Meter Swim, or 2-Lap 1500 Meter swim in Boulder Reservoir, followed by a 5k run on the reservoir dam on 8 Thursday evenings (plus one Wednesday evening) throughout the summer. Many participants make their open-water swimming debut in the beginner-friendly Stroke & Stride 750 meter event, while more seasoned athletes get the thrill of starting alongside some of the top athletes in the world in the 1,500 meter swim. 250-400 participants enjoy the Stroke & Stride every week! Live timing, great post race food, beanie for 6-pack entries, and series prizes are just the beginning!

Tri Boulder
2026-07-18 | Boulder Reservoir, 5275 Reservoir Road, Boulder, CO, 80301, United States
As one of Colorado’s most popular summer triathlons, Tri Boulder offers many different multisport race distances, all in one eventful day! Join us for a full day of racing at the Rez.

Steamboat Lake Triathlon
2026-07-26 | Steamboat Lake State Park, 61105 County Road 129, Clark, CO, 80428, United States
After last summer this event instantly became a personal favorite for our staff, volunteers, and athletes – come find out why! We couldn’t be more excited about this course, this lake, and the overall experience. The swim starts out in the surprisingly warm waters of Steamboat Lake (74 degrees average race temp), then athletes transition to the most scenic bike course you’ll ever find. You’re more likely to see a herd of cattle crossing the road than be passed by a vehicle! After a ride through the rolling country-side athletes will transition to a 3.5 mile run course that’s 50% on road, and 50% on the dirt trails that hug the lakeside. When we tell athletes you’re running through wild flower meadows, we’re not exaggerating.
Pack the camping gear and make a weekend getaway for your all your friends and family! This year we’re also offering a aquabike, and stand-up paddle-board division!

Stagecoach Gravel Triathlon
2026-08-02 | Stagecoach Reservoir (Steamboat Springs), 25500 County Road 14, Oak Creek, CO, 80467, United States
We didn’t get the chance to launch this race in 2020, but that didn’t diminish our passion for this brand new style of triathlon! To say this race is “unique” would be an understatement! Limited to just 250 athletes, we’re excited to announce the first ever gravel triathlon to the Colorado triathlon landscape! This event is set at Stagecoach Reservoir, a quiet and picturesque lake just 15min south of Steamboat Springs, with camping options for the entire family.
After the swim in the waters of Stagecoach Reservoir, it’s time to bring out either the gravel bike, road bike, or mountain bike. Just leave your triathlon bike at home. The course starts out with a short-paved section of 2.1 miles, before transitioning to rolling gravel country roads through some of the most scenic terrain imaginable. The total bike distance is 16 miles, with the final 3 miles of the course on pavement as athletes head back towards the transition area! Once off your bike of choice, it’s time to toss on those running shoes for a 4-mile run on a gravel trail that hugs the shoreline of Stagecoach Reservoir, (Note: ½ mile total on paved roads)! Come join us for this one of a kind triathlon experience, complete with a stand-up paddle-board option for the non-swimmers!

Tri Boulder
2026-08-09 | Boulder Reservoir, 5275 Reservoir Road, Boulder, CO, 80301, United States
Rocky Mountain Tri-Fest was established in 2023 to cater to the whole family. With events for everyone from mom and dad looking to try their hand at a gravel triathlon, to children looking to do their first triathlon.
The Sprint and Super Sprint gravel Tris are beginner friendly with the bike course on the gravel roads surrounding the reservoir. The road are graded and smooth, so you can use almost any bike, even a road bike with wide tires.
The Mini and SSS were created for the younger members of the family, but adults are more than welcome to tag along. These distance take place entirely inside the reservoir, and are 100% about having fun.
We are super excited to be able to offer the kids race for free in 2025. We hope that this will allow more families to join and an introduce this great sport to their children. Use code Rockymountainkids on the USAT membership link to take advantage of a free day license for you children as well.
What bike do you recommend? Do I have to use a “gravel” bike? The simple answer is you can race this course on a mountain bike, on a “gravel” bike, on a cyclocross bike, or even on a road bike with a minimum of 25mm tires and low psi. A tribike and disc wheel would be a little tricky.
For the kids races, anything goes Strider, tricycle, bmx, mountain bike, etc. Please make sure they have a helmet.

Boulder Rez Marathon
2026-08-15 | Boulder Reservoir, 5275 Reservoir Road, Boulder, CO, 80301, United States
This amazing run course will take you alongside the Boulder Reservoir, remaining mostly on dirt roads and trails. The course is flat with only 200 feet of gain, and will provide views of the Boulder Reservoir and Rocky Mountains.

Outdoor Divas Sprint Triathlon
2026-08-16 | Union Reservoir (Longmont), 461 County Road 26, 80504, United States
The Outdoor Divas Sprint Triathlon features a half mile lake swim, a flat and fast single loop 12.4 mile bike, and finishes with a 3.1 mile run on a gravel road that hugs the lake.

Boulder Sunset Triathlon
2026-08-29 | Boulder Reservoir, 5275 Reservoir Road, Boulder, CO, 80301, United States
Join us for an unforgettable morning at the Boulder Reservoir. Although this race does not take place at sunset, it will take place at the end of the summer– it’s sister race is the Boulder Sunrise in June. Experience gorgeous views at the recently upgraded venue. All participants receive stellar race shirts and finisher medals, too. This race is a favorite for beginners due to the flat bike course and a packed dirt trail run course.

Littlefoot Triathlon
2026-09-12 | Bear Creek Lake Park (Lakewood), 15600 W. Morrison Road, Lakewood, CO, 80228, United States
Enjoy a fun late season tri at beautiful Bear Creek Lake Park in the Lakewood/Morrison area. Set at the base of the foothills, the Littlefoot Triathlon starts off with a 750 meter swim in Soda Lake, with water temps expected to be approximately 70 degrees. Next, a rolling bike 15K bike ride that covers nearly the entire park, offering great views throughout! Finish it up with a scenic 5K run on a bike path that winds through the park.

Oktoberfest Sprint Triathlon
2026-09-20 | Union Reservoir (Longmont), 461 County Road 26, 80504, United States
The Oktoberfest Sprint Triathlon features a half mile lake swim, a flat and fast single loop 12.9 mile bike, and finishes with a 3.1 mile run on a gravel road that hugs the lake. Please see course maps for a full description. Overall this is a beginner friendly course, and sets up very well for family and friends to spectate right alongside the action. The best part of Union Reservoir is how close the transition area, start line, finish line, expo area, and parking are to each other!

Last Call Triathlon
2026-09-27 | Boyd Lake State Park (Loveland), 3720 N County Road 11-C, Loveland, CO, 80538, United States
Yes! I want ONE MORE adventure!! Escape to the lake! The Last Call Triathlon will be an event you’ll look forward to all season long. Why? Beautiful mountain views, great weather and a family fun venue! Did we mention camping? Yup! There’s that too. Sitting on the east side of Loveland and southeast of Fort Collins, this close-to-home race day will have a family feel that’s intimate, fun and uniquely challenging. The course layouts make race morning packed with spectator cheering and multiple athlete flybys. With ON-SITE camping options, make a weekend out of this event and plan some extra relaxation time.

Narrowleaf Lake Run
2026-10-31 | Boyd Lake State Park (Loveland), 3720 N County Road 11-C, Loveland, CO, 80538, United States
Brisk autumn running in Colorado – OH YEA! Join us for a family fun event with FIVE distance options at the beautiful Boyd Lake State Park venue.
Choose your adventure! Heavy 5K, 10K, 15K (4, 7 or 10 mile) or 1 Mile Pumpkin race options. There is also a Kid’s Fun Run (1 & 1/2 mile options) as well!
This course is on perfectly paved walkways with about a half mile being off road on the south loop. Beautiful lake and wildlife views, NO vehicle traffic to worry about and fun post race festivities. Did we mention almost no elevation gain? This is one flat course making sure you’ll set a new PR or enjoy a fun steady-paced morning run race.
What’s a “Narrowleaf”?? The Narrowleaf Cottonwood Trees are the most densely populated tree species at Boyd Lake State park. We thought the name was fitting and unique to this venue.
