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Great Flume to the Colorado Trail

 4.4 (5)
Trail Mapped Wrong?


17.3 Miles 27.8 Kilometers




2,450' 747 m


-2,444' -745 m



Avg Grade (3°)


Max Grade (15°)

11,785' 3,592 m


9,771' 2,978 m




Getting forecast...

A strenuous expert loop featuring a unique, underridden area trail and an outstanding CT downhill!


Overview [Suggest Changes]

An atypical loop from Tiger Road to the historic Great Flume Trail. This is one of the most underutilized trails in the Swan River basin and a true gem.

Georgia Pass Road averages nearly 20% grade from the end of the Great Flume to the top of the pass. Expect to hike your bike up some of this climb.

The Colorado Trail from the top of the climb to Middle Fork Swan Road is very technical, particularly in the latter half. The Middle Fork section of the Colorado Trail features an exceptional downhill to North Fork Swan Road.
Features: -none- [Add/Remove]
Dogs: Leashed

Need to Know [Suggest Changes]

Georgia Pass (South Fork) Road is an extremely difficult climb. The route tops out above timberline. Be aware that temperatures can drop quickly, and weather can change rapidly.

Georgia Pass and American Gulch Road are both mixed use. Expect motorized traffic on both roads. American Gulch is extremely popular with dirt bikes as it features huge rollers and banked turns.

This loop can be paired with Galena Gulch to Colorado Trail - West Ridge loop for a longer ride of approximately 30 miles.

Description [Suggest Changes]

From Highway 9, go east on Tiger Road 5.7 miles passing the Dredge Trailhead after 2.6 miles to the intersection with the North Fork Swan Road. There is a wide gravel shoulder on the south side of Tiger Road. This is the best parking for the loop. The Dredge Trailhead Parking Lot is also a good option if extending the loop to include West Ridge, and/or Galena Ditch Trail.

Ride up Tiger Road, crossing a single-lane bridge just after the parking area 1/2 mile to Georgia Pass/South Fork Swan Road (Forest Road 355). Go right on Georgia Pass Road and climb steadily for just under a mile. Turn right onto to GH 93, American Gulch Road, just before a creek crossing.

The road climbs at a manageable 6% grade for the first 3/4 miles before becoming progressively steeper. Ignore any trails branching off the main road. At 1 1/2 miles into the American Gulch Road climb, pass an abandoned townsite. The intersection with the Great Flume Trail is 1/3 of a mile past the townsite on the left side of the road.

There is a wooden chicane and trail marker post identifying the beginning of the Great Flume Trail (GH 92). Historically, the great flume was over 15 miles long. The trail section utilizes 4 miles of the historic flume. Along the flume, remnants of hydraulic mining efforts, and timber, flume support structures are still visible.

The Great Flume begins as a mining road. After crossing a large tallus area (the remnants of a massive hydraulic mining operation) there is a fork in the trail. Take the right, uphill fork and ride to an historic cabin. To the right of the cabin, pass through another wooden chicane onto a singletrack which climbs briefly before reaching the flume. The next 4 miles along the flume is easy to follow. The flume ends at Georgia Pass Road at another chicane.

Turn right up Georgia Pass. It is a grueling, one mile climb to the summit of Georgia Pass. From the summit of Georgia Pass, go left on the steep (8%), rocky 4-wheel drive, Glacier Ridge Road (Forest Road 258). After a 1/2 mile climb, the road intersects the Colorado Trail. Go left onto the Colorado Trail, and begin the first leg of a ripping descent. 3 miles into the descent, the Colorado Trail intersects the Edwin Carter Trail, and in another 1/3 mile a non-system section of the Great Flume. Each of these intersections is marked with a metal NO MOTOR VEHICLES sign.

After this intersection the CT becomes much more technical; descending through a progression of rock gardens eventually to the Middle Fork Swan Road. This is the end of the "South Fork" section and beginning of the "Middle Fork" section of the CT.

Cross the Middle Fork Swan Road and continue on the Colorado Trail. The CT climbs initially before topping out after 1/2 mile and beginning a swooping descent to the North Fork Swan Road. At the North Fork Swan Road, take a left and descend back to the car.

...or continue up the North Fork/West Ridge section of the CT (shut up legs!)


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Your Check-Ins


Sep 30, 2017
Tom Hoskins
First 1.5 miles on the CT decent had patches of snow. 'Tis the season. Amazing loop!
Jul 17, 2017
Fredrik Pettersson
Jul 2, 2017
Daniella Lugo
Jun 25, 2017
Mark Johnson
Be enough challenge to keep the beautiful, swoopy, techy, singletrack quiet, and feels remote. Georgia Pass is a motorhead's paradise, but worth it.
Oct 27, 2016
Fritz Ritter
Wow! 17mi — 3h 30m
Sep 9, 2016
Jason Mccarthy
Oi vey, this was a challenge, no doubt. Being from lower altitude probably didn't help me, it was quite a strenuous ride! Lots of roots and rocks! 17.3mi — 5h 30m

Trail Ratings

  4.4 from 5 votes


in Front Range


  4.4 from 5 votes
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