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blueBlack CDT Alpine Tunnel

  4.3 ( 28 ) Favorite


18.0 mile 28.9 kilometer loop
40% Singletrack


Ascent: 2,427' 740 m
Descent: -2,443' -745 m
High: 12,295' 3,747 m
Low: 9,980' 3,042 m


Avg Grade: 5% (3°)
Max Grade: 20% (11°)


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Historic high alpine riding.

Adam Kagy

E-Bikes Unknown

Features -none-


This ride has it all. A historic ghost town, railroad history, primitive high alpine singletrack and a fantastic descent.

The traffic on this trail is surprisingly low given the uniqueness of the singletrack and history surrounding the area. Go during the fall to get a special experience of fall color in the aspens and alpine tundra.

Need to Know

Since much of this trail traverse high alpine tundra at 12k feet, it usually won't be snow free until sometime in June or even July. Consequently it will also be under snow much earlier than most rides as well.


This ride starts in the historic ghost town of St. Elmo. Ride Southeast on Forest Service Road 295. This is the old historic Denver/South Park railroad grade. Since it's a railroad grade, the climb is gradual and easy. After around 6 miles, you'll pass by the old townsite of Hancock. Look for a bridge and cross it.

From here, look for the Alpine Tunnel trail sign. You'll now be on the Tunnel Lake Trail singletrack. Ride west for about 2 miles then look for a trail sign for the Continental Divide Trail to your left and take this trail. The next 1/2 climbs steeply up to the saddle where you'll come to another signed trail junction. Take a ride to stay on the CDT.

If you feel like you have the energy and time, you can stay straight on this trail (Alpine Tunnel Connector) which will drop down around 400ft and 3/4 mile off the saddle down to the west portal of the Alpine Tunnel. This short out and back is well worth the effort as there is an old restored rail station with multiple photographs and artifacts available to view inside. It also makes for a nice lunch spot and a shelter from the wind.

While on the CDT enjoy the primitive singletrack and amazing views all around. The first 1.5 mi climbs up to a saddle steeply at times. Soak in the view of Tunnel Lake to your ride and enjoy this unique piece of singletrack that can be overgrown and grassy at times. Once the climb up the saddle is finished you'll have a fairly technical, fun and rocky descent. After the quick descent is done you'll have 1 more fairly short and quick climb before the trail flattens and rolls along the alpine tundra.

The next part of the trail is the reward. The descent starts out with a few drainage step downs and above tree line rolling tundra. After a short while you'll enter the trees and the trail will become very smooth, flowy and fast. Be careful with speed here as the switchbacks come up quickly and turns are sometimes sharp. Near the end you'll cross a wooden bridge over a stream and eventually end up at a dirt road (FS 267). Take a right here and follow it back to St. Elmo and your car.

History & Background

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Sep 22, 2018
Alicia Kordonowy
Sep 17, 2018
Brady Pochon
Beautiful day, took time to enjoy the history and trail. 18mi — 5h 37m
Sep 16, 2018
Lee Mebel
Sep 8, 2018
Eric Sims Jr.
Great views, but once you move off the Tunnel trail and head up - you walk up for almost 1000' - loose dirt with loose rocks on top. 17.9mi — 2h 27m
Aug 27, 2018
Chad Drath
Aug 23, 2018
daron topel
Aug 21, 2018
daron topel
Jul 30, 2018
Matthew Noe
truly amazing ride.First climb on CDT is *brutal* but soo worth it! Amazingly remote feel above timberline. VERY grin-heavy descent. 18.8mi — 3h 10m

Trail Ratings

  4.3 from 28 votes


in St. Elmo


  4.3 from 28 votes
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