The kind of 5- to 10-mile hikes that would be considered "day hikes" almost anywhere else simply don't exist on the Colorado Trail. Day hikes here are long and challenging, and they traverse a variety of terrain. There aren't any individual segments less than 10 miles (16.1 kilometers), meaning a day hike might actually be a two-day-long day hike, with camping in between.
For a short hike, the best bet is near the end of the trail, segment 26, Bolam Pass Road to Hotel Draw Road, a relatively breezy 10.9 miles (17.9 kilometers) with a 1,126-foot (343.2-kilometer) incline. With relatively smooth dirt surfaces and the occasional downhill section, it's also a popular course with mountain bikers. There's also segment 3, Colorado Trailhead to Wellington Lake Road, a little bit longer at 12.2 miles (19.6 kilometers) and a 1,268-foot (386.5-kilometer) elevation gain.