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Guide to Races in Colorado

Featured Events

Three Creeks Half Marathon
April 13, 2025

Winter Running Series
Winter 2025-2026

Superior Stocking Run
Dec. 2025

Yeti Chase 5K/10K
Jan. 2026

Ralston Creek Half Marathon & 5K
Feb. 15, 2026

Chilly Cheeks Winter Duathlon Series
Feb. 2026

Mt. Evans Ascent
June 2026

Winter Running Series
Winter 2025-2026

Superior Stocking Run
Dec. 2025

Yeti Chase 5K/10K
Jan. 2026

Ralston Creek Half Marathon & 5K
Feb. 15, 2026

Chilly Cheeks Winter Duathlon Series
Feb. 2026

February 2025

Racing Underground February 2025 Events

Date Event Location Website
tbd Chilly Cheeks Duathlon Cherry Creek State Park - Denver, CO Website

Details: This late February event is a run-bike-run format with each run being 2.5 miles and an 11 mile bike ride in between. The run covers a mix of road, paved bike path and well maintained dirt trails. The bike route is 100 percent paved roads. Road bike and fat tire divisions are offered. Post race hot food & drinks provided.

Other area February 2025 Events

March 2025

  • 2 Cerus Dry Tri (Row/Bike/Run in 45min), Cerus Gym, Frederick, 8:00 a.m., 720.277.3282

April 2025

  • 13 - Salida Pole Pedal Paddle (Backcountry Ski, Mountain Bike, Whitewater Kayak), Salida, Colorado (719) 221-3937

May 2025

  • 10 Ordinary Mortals Duathlon, (3M Run/15M Bike/2M Run), Lake Pueblo State Park, Pueblo, Colorado, 9:00 a.m., 719.549.3363
  • 24 Valley Bottom Rio Trio, (8M Bike/3M Paddle/5k Run), State Ave Bridge, Alamosa, Colorado, 9:30 a.m., 719.589.2105

June 2025

  • 5 Boulder Stroke & Stride (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 7 - Colorado Triathlon - (750m Swim/17M Bike/5k Run) - Boulder Reservoir - Boulder, Colorado - 7:30 a.m.- Lance@WithoutLimits.com
  • 11 Boulder Stroke & Stride (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 14 Ironman Boulder (1.2M Swim/56M Bike/13M Run), Boulder Reservoir, Boulder, Colorado, 813.868.5940
  • 14 San Juan Trail Tri (3.7M Trail Run, 2M SUP/8.7M Mtn Bike), Dallas Creek Day Use/Ridgway State Park, Ridgway, Colorado, 8:30 a.m., Info@SanJuanTrailTri.com
  • 19 Boulder Stroke & Stride (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 21 - XTERRA Lory Triathlon - (0.5M Swim/12.2M Bike/4.8M Run) - Lory State Park - Bellevue, Colorado - 7:50 a.m.- 303.408.1195
  • 21 Lake to Lake Triathlon (1.5k Swim/30M Bike/10k Run) (1.5k Paddle/30M Bike/10k Run), High School, Loveland, Colorado, 6:30 a.m., 970.669.6372
  • 22 South Suburban Kids & Adult Triathlon, Goodson Recreational Center, Centennial, Colorado, 6:40 a.m., 303.483.7034
  • 26 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 29 Boulder Sunrise Triathlon (sprint/Olympic/international), Boulder Reservoir, Boulder, Colorado, 7:15 a.m., info@bbsctri.com

July 2025

  • 10 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 11 Frisco Triathlon (3k Paddle/12k Bike/5k Run), Frisco Bay Marina to Pine Cove Boat Ramp, Frisco, Colorado, 9:00 a.m., 970.668.2558
  • 12 Race in the Clouds Off Road Duathlon (4M Run/13M Bike), Buckskin Street, Alma, Colorado, 7:30 a.m., RaceInTheClouds@gmail.com
  • 12 LG Tri Splash, Grind Sprint Triathlon, (500Y Swim/12M Bike/5k Run) (Kids: various distances), Eagle Pool, Eagle, Colorado, 7:00 a.m., terri@vvcf.org
  • 13 - Boulder Peak Triathlon - (1.5k Swim/42k Bike/10k Run) - Boulder Reservoir - Boulder, Colorado - Lance@WithoutLimits.com
  • 17 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 19 Kids Try-athlon (various distances), H2Obrien Pool, Parker, Colorado, 6:30 a.m., 303.841.4500
  • 19 Tri Boulder (1.2M Swim/50M Bike/12.4M Run) (1.2M Swim/50M Bike) (1500m Swim/26M Bike/6M Run) (750m Swim/17M Bike/5k Run)(5k Run/12M Bike/5k Run), Boulder Reservoir, Boulder, Colorado, 7:05 a.m., info@bbsendurance.com
  • 24 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com
  • 26 South Suburban Kids Triathlon (200Y Swim/4M Bike/2M Run), Cook Creek Pool, Centennial, Colorado, 6:30 a.m., 303.347.5999
  • 27 - Steamboat Lake Triathlon - (750m Swim/12.4M Bike/3.5M Run) (750m Swim/12.4M Bike) (750m PaddleBoard/12.4M Bike/3.5M Run) - Steamboat Lake State Park - Steamboat Springs, Colorado - Lance@WithoutLimits.com
  • 31 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimits.com

August 2025

  • 2 Splash Mash Dash Kids Triathlon, (various distances), Northridge Recreation Center, Highlands Ranch, Colorado, 9:00 a.m., 303.471.7048
  • 3 - Stagecoach Gravel Triathlon - 750m Swim or Paddle/16M Bike/4M Run & Aquabike, Stagecoach Reservoir, Steamboat Springs, Colorado, 8:00 a.m., 303.408.1195
  • 7 Boulder Stroke & Stride, (750 or 1500m Swim/5k Run), Boulder Reservoir, Boulder, Colorado, 6:00 p.m., Lance@WithoutLimit.com
  • 9 Rocky Mountain TriFest (750m Swim/12.4M Bike/5k Run) (400m Swim/6.2M Bike/1.55M Run), Boulder Reservoir, Boulder, Colorado, 7:15 a.m., info@bbscendurance.com
  • 10 - Outdoor Divas Triathlon - (750m Swim/12.4M Bike/5k Run) - Union Reservoir- Longmont, Colorado - 8:00 a.m.- Lance@WithoutLimits.com
  • 23 - Longmont Kids Triathlon & Adult Try-A-Tri - (200Y Swim/4.5M Bike/2k Run) (various kids distances) - Recreation Center- Longmont, Colorado - 7:45 a.m.-303.651.8406
  • 23 Gunnison Valley Triathlon (500m Swim/14M Bike/4.2M Run), Parks & Recreation Department, Gunnison, Colorado, 9:30 a.m., Aeflin@gunnisonco.gov

September 2025

  • 6 - Littlefoot Triathlon - (750m Swim 15k Bike/5k Run) - Bear Creek Lake Park - Lakewood, Colorado - 7:00 a.m.- Lance@WithoutLimits.com
  • 6 Lake Nighthorse Sprint Tri (750m Swim/12.4M Bike/5k Run), Durango, Colorado, 9:00 a.m., 281.467.4072
  • 6 She Sprints Womens Triathlon, (800m Swim/10M Bike/5k Run) (5k Run/21M Bike/10k Run) (1M Run/10M Bike/5k Run), Cherry Creek State Park, Denver, Colorado, 8:00 a.m., hello@shesprints.com
  • 7 Tri the Rock (youth distances by age group), Recreation Center, Castle Rock, Colorado, 7:00 a.m., 303.660.1036
  • 13 Splashland Adult Triathlon (3.4M Run/10M Bike/400Y Swim), Splashland Pool, Alamosa, Colorado, 9:00 a.m., 719.589.6258
  • 13 Deserts Edge Triathlon (sprint/Olympic), Highline Lake State Park, Fruita, Colorado, 8:00 a.m., 970.744.4450
  • 13 Harvest Moon Triathlon (1.2M Swim/56M Bike/13.1M Run)(5k Run/56M Bike/13.1M Run)(12.M Swim/56M Bike), Boulder Reservoir, Boulder, Colorado, 7:30 a.m., info@bbscendurance.com
  • 14 Deserts Edge Triathlon (sprint off-road & Collegiate draft legal), Highline Lake State Park, Fruita, Colorado, 8:00 a.m., 970.744.4450
  • 21 - Oktoberfest Triathlon - (750m Swim 12M Bike/5k Run) -Union Reservoir - Longmont, Colorado - 8:00 a.m.- Lance@WithoutLimits.com
  • 27 Black Canyon Triathlon (500m Swim/24k Bike/5k Run), Community Recreation Center, Montrose, Colorado, 8:00 a.m., 970.596.4108
  • 28 - Last Call Triathlon - Various Events & Distances - Boys Lake State Park - Loveland, Colorado - 7:00 a.m.
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