The man who died while bicycling on the Colorado National Monument on Saturday (October 3) has been identified.

The man, 67-year-old David Kieth Siefkas of Denver, was participating in the Tour of the Moon Grand Cycling Classic. According to reports, he collapsed after stopping at the Monument's upper Ute Canyon trailhead.

Siefkas died at the scene after attempts by paramedics to resuscitate him were unsuccessful. The Mesa County Coroner determined Siefkas death was caused by cardiac arrest. The coroner also ruled the manner of death as natural causes.

Organizers of this year's Tour of the Moon say the event was a sell-out with 2,000 registered riders. The event works in partnership to raise money for the Colorado Riverfront Commission and Bicycle Colorado.

[KKCO 11News][Western Slope Now.com]