Gregory Canyon

It’s a trailhead and it costs $ 5 to park. I hiked the flatiron mountain with my girlfriend during the winter with some snow and ice. I would say most of the hiking is fairly easy, but it can be slippery at times, but we probably didn’t have appropriate equipment. It gets a bit harder toward the top of the mountain, though. I’ve never really hiked much before, but some locals told us when we were nearly at the top, that it was probably not a good idea to continue without chains on our boots or picks to stay in place. We kind of regret listening and not just reaching the top of the 1^st/​2^nd flatiron trail, but my girlfriend and I had fun nonetheless.

Easy trail that I was able to do in under an hour and I’m 6 months pregnant. Gradual incline, the trail is rocky and can be muddy or icy but easy to do as family day out. On sunny days, parking can be a pain so get there early or be very patient. Over all great and easy trail, I’ll also recommend «Shadow Rock», which is a trail opposite (south fork) of The Canyon trail.

Marvelous trailhead with access to miles and miles of steep trails. You can probably access all of Boulder Mountain Park from this trailhead, and it’s only about a mile from CU. Take Baseline west until the hairpin right turn where the road turns into Flagstaff; turn left instead to enter the short (~.25 mile) fee-​enforced paved parking area. The trailhead area has bathrooms and a gate that closes at sundown. There’s also free parking (in gravel pullouts) and access to other trails less than a quarter mile from the fee area. It’s a pretty well-​maintained (but not overly manicured) trailhead.
The trails themselves are much more serious and technical. Nothing too extreme that you’d need a rope (unless you want to go off-​trail and make it that way), and you don’t have to traverse any precipitous cliffs, but it would be pretty impossible to bike these singletrack trails unless you’re a magic goat. I could only run about three quarters going up; most of the trail is like a rock staircase. Trails are definitely well-​maintained (wooden steps here and there in good condition). The knife-​edge peaks are probably a lot of fun for a serious boulderer.
I took Saddle Rock trail all the way to Green Mountain Peek (~2300 ft climb). About 1.3 miles up (~1200ft climb), Saddle Rock meets Amphitheater. If you’re up for a quick (~30ft) rock climb, you go up a large pile of boulders to get a panoramic view over the countryside east of the Flatirons. Continue up to Green Mountain summit to conquer the jagged Flatiron ridgeline and get the full 360 degree panorama. You can peer down into Kossler lake and even see some snowy peaks along the western horizon. Turn around and you can see Denver, and (perhaps with enough beer) even Kansas.