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Whether a race, special group ride, training opportunity, or cycling-related community event, the 303 calendar showcases it all.  To have an event posted here please follow this link:  Event Policy Submission & Guidelines.

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April 2019

Three Creeks Half Marathon

April 6
Cherry Creek State Park, 4201 S Parker Rd
Aurora, CO 80014
+ Google Map

Denver   Racing Underground brings you an amazing half marathon this spring! The Three Creeks Half Marathon features a USA Track & Field certified half marathon course that is flat, fast and scenic! Travel on foot through some of the most beautiful parts of Cherry Creek State Park, with a total combined elevation gain of only 291 feet spread out over 13.1 miles as the course follows the banks of Cherry Creek, Windmill Creek, and Cottonwood Creek on a mix…

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Barkin’ Dog Duathlon

April 20
Cherry Creek State Park, 4201 S Parker Rd
Aurora, CO 80014
+ Google Map

Denver   The Barkin' Dog Duathlon celebrates 22 years as the kickoff race for the summer multisport season! The Barkin' Dog is Colorado's largest duathlon, and consistently one of the largest duathlons in the Western United States. This race attracts some of the top pros in the country as well as a whole slew of first-time multisport athletes trying something different. If you can finish a 5K, you can complete a duathlon! Participants can choose from the standard 5K Run,…

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June 2019

Mt. Evans Ascent

June 8
Mt Evans Idaho Springs, CO United States + Google Map

Idaho Springs Although the air will be noticeably thin at the starting line, Echo Lake's 10,600 feet of elevation is just the beginning. The climb totals nearly 4,000 vertical feet - much of it above treeline - as you make your way 14.5 miles to the finish line located at the summit of one of the most recognizable peaks on Denver's mountain skyline - 14,264 foot Mt. Evans. Be inspired!!! Join us on June 8, 2019 for another memorable run.…

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January 2020

Yeti Chase 5k/10k

January 19, 2020
|Recurring Event (See all)

An event every year that begins at 12:00am on day third of January, repeating until January 19, 2025

Bear Creek Lake Park Lakewood, CO United States + Google Map

Morrison   This 5k/10k run is brought to you by Racing Underground. Conveniently located on the scenic west side of metro Denver, Bear Creek Lake Park is known for it's diverse bird and waterfowl population as well as stunning views of the foothills. The 5k and 10k races wander it's 2500 acres with a mostly flat 5K course, while the 10k throws in a few rolling hills. The race has sold out weeks before race day every year, and offers…

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February 2020

Ralston Creek Half Marathon & 5k

February 2, 2020
|Recurring Event (See all)

An event every year that begins at 12:00am on day first of February, repeating until February 2, 2025

Arvada   The Ralston Creek Half Marathon and 5K returns in 2019, after sold out fields in the half for the past 7 years! Join us at Colorado's Premier Winter Half Marathon, and the finale to the 2018-2019 Racing Underground winter running series. The Ralston Creek races feature a fun winter half-marathon and 5K run conveniently located on the west side of the Denver Metro Area in Arvada, Colorado. The courses covers a scenic mix of road and bike path…

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