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CDT Alpine Tunnel

 4.1 (42)

Historic high alpine riding.

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12,295' 3,747 m


9,980' 3,042 m


2,427' 740 m


2,443' 745 m



Avg Grade (3°)


Max Grade (11°)

Dogs Unknown

E-Bikes Unknown


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 right 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

Shared By:

Adam Kagy with improvements by Jeff Welch and 1 other

Trail Ratings

  4.1 from 42 votes


in St. Elmo


  4.1 from 42 votes
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in St. Elmo


in Colorado


17 Views Last Month
18,815 Since Sep 19, 2014



Buff and scenic. The Alpine Tunnel Trail is great.
Jul 16, 2018 near St. Elmo, CO
Fall time at Tunnel Lake.
Sep 19, 2015 near Buena V…, CO
Reaching the saddle
Sep 19, 2014 near Buena V…, CO
Fall time at Tunnel Lake
Sep 19, 2015 near Buena V…, CO
High above- on the CDT Alpine Tunnel trail
Sep 19, 2014 near Buena V…, CO
Quick 100yrd hike a bike from the CDT and Alpine Tunnel junction
Sep 19, 2014 near Buena V…, CO


Current Trail Conditions

Minor Issues 39 days ago
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Sep 2, 2023
Kaile Vierstra
This trail is worth it for the views (spectacular) but the trail itself is just okay. Mostly a hiking trail with some fun descents. GF trail.
Oct 10, 2022
mel eg
Aug 29, 2021
Geoff Guthrie
Spectacular scenery, sweet old school alpine singletrack, and smooth flowy descent to Tincup Pass Rd. Wonderful mountain bike loop in Colorado! 18.2mi — 3h 01m
Jul 25, 2021
Abe Proffitt
35.9mi — 7h 15m
Jul 9, 2021
Kendall Beggs
80% of the climb is fun, the test hike-a-bike. The descent starts off rocky but ends up pretty fun. The last descent on the road is incredibly bumpy. — 2h 30m
Aug 22, 2020
Scott F
Aug 14, 2020
Dave Smith
hope you like hike a bike! I would do this again, minus the CDT. the Alpine Tunnel Trail is awesome.
Aug 8, 2019
Don Mattsen