Kieren Duncan knows his speed only gets him in the door to the NFL. It’s up to him to be more than just fast to stick around.

The wide receiver/kick returner from Division II Colorado State-Pueblo wasn’t on the NFL radar until he ran blazing times in pre-draft workouts — an electronic 4.32 40-yard dash at a regional combine in Tempe, Ariz. in February; and an official 4.29 and a hand-times 4.25 at his pro day on March 29.

Even then, the 5-11, 170-pound Duncan not only was undrafted but received only a mini-camp tryout offer from the Bears following the draft. But he made the most of it and earned a spot on the Bears’ 90-man offseason roster.

“It always helps when you’re faster than most of the guys you’re playing with,” Duncan said. “But this is the NFL — it’s a completely different animal. Everybody’s fast now. It’s not only about raw skill-set. It’s about technical things as well.”

Duncan had 36 receptions for 622 yards (17.3 avg.) and six touchdowns for CSU-Pueblo (12-2) in 2015 and averaged 30.1 yards per kickoff return — sixth in D-II — with one touchdown. As a junior he had 45 receptions for 712 yards (15.8 avg.) and three touchdowns to help the ThunderWolves (14-1) win the Division-II national championship.

At Colorado State-Pueblo, Duncan was more than just a football player. As a senior, he won a Society of Professional Journalism regional “Mark of Excellence” award for sports writing for a feature story he wrote for the school’s publication — CSU-Pueblo Today — on a former ThunderWolves player joining the coaching staff. On the field, he knows he has to be just as versatile and well-rounded.

“I’ve tried to complement my speed by making sure that I’m not just one of those guys who can run in one direction,” Duncan said, “and really hone my routes; really hone the technical side; make sure I can do other things, catching punts and contributing any way I can. Stuff that relies on more than just speed.”

Even Duncan, who grew up in Goodyear, Ariz., wasn’t considering the NFL seriously until seeing rave reviews of his impressive 40 times. So getting this far is a trip. He used to admire 5-10 Eddie Royal from afar as an undersized receiver who made it in the NFL. Now he gets tips from Royal during drills and practices.

“It’s crazy,” he said. “Every day you’re walking past people like Eddie Royal, who I’ve grown up watching from Denver and everywhere. Seeing the Chicago Bears logo on everything that you’re doing. It’s just surreal. When I signed, I called my parents and I broke down. It’s just been a really tremendous experience.”