I must apologise in advance for the routes I have not included here. For those of you unfamiliar with Boulder, it is an absolute paradise for trail running – I can’t possibly do justice to all it has to offer. There are certainly places with more trails, but they tend to be in national parks or other far-flung destinations. I have included some of my personal favorites, but as I continue to explore I will add to the list.

A few comments about conditions/preparation: some of these runs will have you gaining a lot of elevation. In addition, you may be exposed to all of the wind the Rocky Mountains have to offer, which is considerable. Therefore, I always bring a full additional layer of clothing. My philosophy is this: what will I want with me if I break my ankle and have to spend the night sheltered under a rock? It hasn’t happened to me yet, but I have certainly had to draw on my clothing reserves. I also carry first aid essentials: athletic tape, wound closures, water purifying tablets and the runner’s best friend: ibuprophen. If you are doing a run with a lot of ascent, you also have to plan for more water than you typically carry. I figure a liter for every hour I plan to be out will be about right, but I’m sure some people would say bring more. Lastly, many people stay off the trails from 30 minutes before dark to 30 minutes after dawn in order to avoid mountain lions. Statistically, there are actually more fatal hamster encounters, but I’d rather not go into the specifics of that.

Most of the trails are pretty well marked, but I always carry a map with me, just in case. You will probably want one for route planning, at the very least. The best map to have is the Open Space and Mountain Parks map, put out by the city of Boulder. It is not a topo, but provides more detail on trails than any other map I’ve found. The link below includes both a PDF version of the map for printing as well as Boulder locations that carry the map. OSMP
Map

If you are new to running, you may also want to check out this guide: Running to
lose the “Buddha Belly”.

Marshall Mesa/Doudy Draw Loop

220M / 722’ Vertical
14.5K / 9 miles

This area is probably the best place to go in the area if you are training for a road race, but want to run on trails to save your legs. There are contours, but nothing like what you get in some of the other runs here. It also affords spectacular high plains views, with Eldorado Canyon and Boulder Mountain Park as your backdrop. I like Marshall Mesa in particular, as it reminds me of the Yorkshire Moors in England, one of my favorite landscapes and places to run. The Boulder Open Space & Mountain Parks map covers this area, and you’ll find other maps pretty much useless. Their is a detailed map posted at the parking area I’ve shown the start, and sometime there are even leaflets with a map.

Walker Ranch Loop

378 M / 1,240’ vertical
11.6 K / 7.2 miles

Walker Ranch is in the mountains just outside of Boulder, off of Flagstaff Road. The terrain is very similar to White Ranch, featured in my guide about Denver trail running. Like White Ranch, it is also a mecca for mountain bikers. It is a great place to go if you feel like getting into the mountains, but don’t have much time.

The loop I have laid out is pretty much your only option unless you want to do a shorter out-and-back. It nets out to be a fair amount of climbing, but no single climb is all that big.

Green Mountain Loop

12.7K/7.9 miles
664M/2,178’ vertical

This route is tough if you are not used to climbing. The total elevation gain is not much less than most 14’er hikes, though with a little more oxygen. If you want to run this, I strongly recommend doing the route clockwise, as the trail up Bear Creek is runnable, while Gregory Canyon gets pretty steep. My route does not actually take you to the top of Bear Peak, but you get within only a few hundred meters away, so worth the diversion if you haven’t been. If you do go to the top, you can return to the parking area via the Saddle Rock trail, which is a little harder to run than Gregory Canyon, but all down hill. You can also backtrack and follow my recommended route. I don’t have a strong preference either way – they are both really nice trails.

Bluestem/Mesa Trail Loop

224M / 735’ vertical
8.8K / 5.5 miles

Bluestem is truly spectacular in the spring through early fall. Because of the geography, it gets more water than most of the Front Range, so feels more like a mountain medow than the surrounding arid plains. There isn’t a proper parking area at the start I’ve chosen, but there are usually spots along the street. This is also a great place to park if you are  heading up Bear Peak.

One of the tricks to getting the most out of Boulder Open space is learning all of the trail heads and legitimate parking spots. Most places where you see a trail meet a road, there will be a place to park, but they are often poorly marked and very residential. It’s worth some trial and error, though, as some of the nicest trails are the less-used ones that connect neighborhoods to the Mountain Park.

Bear Peak/Shadow Canyon Loop

770M / 2,526’ vertical
15.4K / 9.6 miles

This route starts at the NCAR facility on Table Mesa. There is tons of public parking on top of the mesa, which is a great starting point for all kinds of runs/hikes. For this route, I strongly recommend that you go counter-clockwise, as the Bear Creek trail once again provides the most gradual access to the higher elevations of the Mountain Parks. I find I can run most of this route, but I have to hike the last few hundred meters approaching Bear Peak. The route I’ve shown here gets you really close to Bear Peak summit, but takes you over towards Shadow Canyon before you quite make it. As with Green Mountain, well worth the diversion to go to the top if you haven’t been. There’s actually a nice little rock scramble to get to the very peak and enter your name in the log book. The trail from Bear Peak to Shadow Canyon can be a little hard to follow if there’s been snow recently. Don’t be alarmed if you feel like you’ve lost it. Just try to stay at pretty much the same elevation and bear to the left/east when you can. There is saddle between Bear Peak and South Boulder Peak - you’ll find a trail marker where the Shadow Canyon trail starts, and the trail is pretty hard to miss. As long as you don’t head down and West from Bear Peak, you’ll be fine. Shadow Canyon is one of my favorite trails in the area. It deserves its name, as it is very steep and protected. Massive boulders are strewn along the trail, as if giants made this their playground long ago. The descent is like going down a stone staircase. Not recommended for bad knees.

I have intentionally left Mount Sanitas off this list, though it is a popular running destination. It is too crowded for my taste.

One more thing worth mentioning: at higher elevations you will need traction in Winter. Many of the trails get slippery, and the trails up Bear Peak and Green Mountain get positively treacherous from December through Spring. Many people use Yaxtrax, which are stretchy rubber with coiled spring-like wire and fit over any kind of shoe. I’ve found that Yaxtrax don’t hold up very well to the abuse of trail running, and don’t provide enough traction on steep descents. I carry Kahtoola running crampons with me, and put them on as needed. Kahtoolas are awesome. Neptune Mountaineering in Boulder carries them. Another option: some trail runners screw sheet metal screws straight into their shoes. I’ve done this too, and it provides about as much traction as Yaxtrax, but holds up better and costs less.