Lower Sam Merrill to Sunset Ridge to El Prieto Loop

Consensus:    (details)
  4.4 from 13 votes
blueBlack  Intermediate/Difficult from 8 votes
Rank: #10 in the Southern California area
#41 in CA, #482 Overall
Views: 7,293. Last 30 days: 157
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Featured Ride in the area near La Cañada Flintridge,
“Classic Altadena loop with the Lower Sam Merrill climb to Sunset Ridge & El Prieto single tracks.”
Christopher Woodruff on Jun 1, 2013
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14.323.0 milesKilometers 2,618’798 m Ascent 3,471’1,058 m High 7% Avg Grade (4°)
60% Singletrack -2,618’-798 m Descent 1,152’351 m Low 33% Max Grade (18°)
Dogs: Leashed
2:45 average time for 16.4 miles. Details

The Lower Sam Merrill Trail is a steady climb with many tight switchbacks. Please be aware LSM has a lot of hiker traffic. Please be courteous and use a bell. It's best to climb this in the morning as the trail is West facing and there are very few trees for shade. At the top of the Lower Sam Merrill trail, you are rewarded by great views and some local history from the ruins of the old Echo Mountain Resort and Mt. Lowe Railway.

The Sunset Ridge Trail and El Prieto Trail are all technical narrow singletrack. These trails are for intermediate and expert riders only, and intermediate riders will likely have to dismount several sections. Watch out for poison oak when it's in season. Most of the trail is north facing with lots of shade; perfect for poison oak.
Park in the Windsor Ave. lot by the east side of JPL. Ride North on the Gabrieleno Trail, a private paved road, and turn off onto a short dirt climb up to W Altadena Drive. (or ride the pavement on Ventura, Left on Casitas, and Right on Altadena Dr) You'll be riding the road over to the start of the Lower Sam Merrill trail. Continue on W Altadena Drive and turn left at Olive Ave. Turn right onto W Loma Alta Drive and continue to the trailhead when it intersects with Lake Blvd. You'll see a large metal gate and stone work at the entrance to the Lower Sam Merrill Trail area.

Now start onto the dirt section and stay to the right by starting up the Lower Sam Merrill trail. Make your way up all the switchbacks. At the top, you should ride out to the vista point and check out the ruins of the Echo Mountain Resort and Mt. Lowe Railway. There is some decent shade, so it's a great spot to take a break.

Ride the short section back towards the Lower Sam Merrill Trail, but keep climbing to the right on the Mt. Lowe Railway Trail instead. At the end of this trail, you'll come to a paved road. Ride a couple hundred feet down the road and start onto the Sunset Ridge trail on the right. You'll want to open up the shocks for the next descent.

Follow the Sunset Ridge trail down 0.8 miles. Here the trail will come really close to the paved road and another vista point with some picnic tables. Stay right on the trail and continue down the rest of Sunset Ridge for 1.5 miles. At the end you'll meet up with the paved road. Follow this road down for about 0.25 miles.

There will be a trail turning right off the road from here. This is Lower Sunset will take you down into the Millard campground. Keep going on the fireroad through Millard campground and climb for about 1 mile to get to the start of the El Prieto singletrack.

Turn left down the El Prieto singletrack. There are a couple of splits in the trail, but they come back together. I usually stay left on the first split and right on the second split. Enjoy the fantastic technical descent with drops, tight switchbacks, stream crossings, and rock gardens. When you get to a fireroad, continue down, cross the stream and enter the last bit of singletrack on the left. Follow the paved road back out to the parking lot.
View in 3D
4.4 (7)
This is a good, tough loop which includes steep climbs rewarded by great sing...
near Altadena, CA
4.1 (10)
This ride features a steep fireroad climb, cliff-side singletrack, and fast s...
near Altadena, CA
4.0 (2)
Awesome singletrack that drops ~5,000 ft in 7 miles with almost no uphill!
near Sierra Madre, CA

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