There are several interesting bicycle routes from RMNP "down" to Boulder. I put "down" in quotes because all routes involve significant uphill sections. I start from our cabin in Meeker Park, on Hwy. 7 south of Estes Park, about 2 miles south of Longs Peak campground; if you leave from Estes Park, 12 miles and 1,600 feet of elevation gain are required to reach this point.
The first part of the ride from Meeker Park is an easy coast down Hwy. 7 to the North St. Vrain river at Wild Basin; since Allenspark is at the same elevation as Meeker Park, this coasting must be repaid with a climb back up to Allenspark. There is a long downhill stretch to the east in Allenspark where you can go very fast, but be on the lookout for cars going even faster. This is followed by a climb up a hill, which has a scenic lookout area that provides good views of the peaks of Wild Basin.
A bit after the crest of the hill, 4.5 miles from the top of the hill in Allenspark, is a choice point. One possibility is to continue down Hwy. 7 to Lyons. From Lyons, there is a highway straight to Boulder. Lots of cyclists are seen on the Lyons-Boulder highway, but I don't like it: I don't like cars passing a few feet away from me at 70 mph, not to mention the noise, dust, and pollution of the heavy traffic. In addition, this highway has cracks patched with tar at regular intervals (must be a concrete highway underneath), and this produces an unpleasant ka-thump ka-thump each time you cross a tar stripe. A better route from Lyons is to ride a few miles farther east past Lyons to Hygiene, then turn right; by a variety of routes, this takes you past farms, lakes, and prairie dog towns to Boulder, without much traffic.
The second choice after the crest of the hill, 4.5 miles past Allenspark, is to turn right into Peaceful Valley; this is the way I usually go. Across the valley is Smith's Rock. Smith was a horse thief who made the mistake of stealing some Indians' horses. They pursued him, and finally he climbed his soon-to-be namesake rock to escape. Having not brought their climbing gear, the Indians did not pursue him up the rock; they just camped around the bottom and stayed there until he died, probably of dehydration.
The initial part of the road into Peaceful Valley is mercifully downhill. Across from the bottom of the hill, 3/4 of the trees on the hillside are dead, having been killed by drought and pine beetles in a single year. It's enough to make me worry about global warming: this is arid country, and small increases in warmth and drought could wipe the forests from these mountains.
Peaceful Valley is narrow, with a pretty stream at the bottom. In a car, the road seems mostly downhill; on a bike, you soon learn the truth. The truth is, it's a long darn climb up and out of that valley; Rest in Peace Valley might be a better name. There is a dude ranch with stables in the center of the valley; look for an onion-bulb church up the hill on the left.
The crest of the hill is a good place to take a rest break and provides a good view of the Indian Peaks. It is possible to continue on the highway from here to the historic mining town of Ward (with a possible detour to the Brainard Lake area), then go down into Ward and down from there; it is about 5 miles of rolling hills to Ward. Instead I usually turn left, soon after the crest of the climb out of Peaceful Valley, on the road to Jamestown, marked by a green sign.
The road to Jamestown starts as a dirt road. After some up and down sections, there is a fairly steep hill, near the top of which the road becomes paved. This is followed by a long, steep descent into Jamestown, a small quaint town with a few houses, shops, and speed bumps. Continue on the same road past Jamestown until it terminates at a stop sign on another road.
One option is to turn left here, which will terminate on the Lyons-Boulder highway or, with a right turn, on Old Stage Road, a reasonably good route up a hill. The other option, and the one I take, is to turn right (up Left-Hand Canyon toward Ward) for about a mile before turning left onto Lee Hill Road.
If you can ride up Lee Hill Road without having a heart attack, then your cardiovascular system is guaranteed to be good for another year. This is one long, steep mountain. It is beginning to look like suburbs, with quite a few houses, but still quite pretty. At the top of the hill I find two young capitalists selling lemonade by the side of the road -- just what I need! I stop and buy two cups of lemonade and take a break before starting down.
The descent of Lee Hill Road into Boulder is long and steep. I worry that my rims will overheat from brake friction and cause a blowout, so I stop a couple of times to let the rims cool. At the bottom of the hill, the terrain is dead flat and you're in Boulder. It's amazing how the Rockies rise so abruptly from the plains.
Distance from Meeker Park to McGuckins (one of the world's better hardware stores) in central Boulder is 38.5 miles; elapsed time 2 hours 40 minutes.
Rocky Mountain National Park: The High Peaks