Picnic area & Arroyo Seco – El Prieto Trail loop from Altadena
Picnic area & Arroyo Seco – El Prieto Trail loop from Altadena
2.6
(22)
64
riders
Picnic area & Arroyo Seco – El Prieto Trail loop from Altadena
02:14
23.6km
560m
Mountain biking
Hard mountain bike ride. Good fitness required. Advanced riding skills necessary. Some portions of the route may require you to push your bike. The starting point of the route is accessible with public transport.
Last updated: May 8, 2026
Tips
Your route passes through protected areas
Please check local regulations for:
Waypoints
Start point
Bus stop
Get Directions
3.56 km
Gabrielino Trail (NRT)
Highlight (Segment) • Trail
Tip by
7.37 km
Picnic area & Arroyo Seco
Highlight • Rest Area
Tip by
11.3 km
Upper Arroyo Seco
Nature Reserve
18.2 km
El Prieto Trail
Highlight • Trail
Tip by
23.6 km
End point
Bus stop
Way Types & Surfaces
Way Types
11.7 km
7.51 km
2.52 km
1.83 km
< 100 m
Surfaces
11.5 km
4.82 km
2.74 km
2.56 km
1.93 km
< 100 m
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Elevation
Highest point (720 m)
Lowest point (350 m)
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Weather
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Today
Saturday 27 June
24°C
14°C
0 %
Additional weather tips
Max wind speed: 13.0 km/h
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Our route recommendations are based on thousands of hikes, rides, and runs completed by other people on komoot.
Description
If you're looking for a truly challenging and rewarding mountain biking experience in Southern California, the Picnic area & Arroyo Seco – El Prieto Trail loop from Altadena delivers. This difficult 14.7-mile (23.6 km) route packs in 1821 feet (555 metres) of elevation gain, taking roughly 2 hours and 14 minutes to complete. It's a ride best suited for advanced mountain bikers with excellent fitness, offering one of the region's most celebrated singletrack adventures.
What to expect on Picnic area & Arroyo Seco – El Prieto Trail loop from Altadena
This loop is a dynamic journey through a lush, oak-lined canyon, a welcome shaded relief from the typical exposed trails of Southern California. You'll encounter a mix of terrain, from a significant fire road climb that leads to an awesome singletrack downhill, to sections with extreme height exposure, 180-degree switchbacks, and mandatory drops. The El Prieto Trail itself is renowned for its technical features, including rock gardens and refreshing stream crossings, making it a black diamond-rated experience in parts. While experienced riders can tackle most of it, don't be surprised if you need to push your bike through some of the more challenging sections.
Planning your visit
The trail system is conveniently located just above Altadena, near the Arroyo Seco and the entrance to the San Gabriel Mountains. This is a multi-use trail, so be prepared to yield to hikers and stop for equestrians; a bell is highly recommended, especially on weekends. Poison oak is present year-round, so keep an eye out. Parking for El Prieto Trailhead Altadena is generally available, but arriving earlier in the day is always a good strategy to secure a spot.
Trail details
- Distance: 14.7 miles (23.6 km)
- Elevation gain: 1821 feet (555 metres)
- Difficulty: difficult
- Estimated time: 2 hours and 14 minutes
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