Henninger Flat from Mount Wilson Mountain Bike Ride



Fire road




Elevation Gain


3273’ per GPS

Starting/Max Elevation


5674’ / 5674’ per GPS

Starting Coordinates


34 13.356’ N, 118 03.764’ W

Climbing to Henninger Flats and beyond to Mount Wilson on the Toll Road was a premier workout ride in the front range of the San Gabriels, until the winter of 2005. The third wettest winter on record resulted in serious damage to many mountain roads, and the Mount Wilson Toll Road was no exception. Since then the entrance gate in Altadena has been locked due to a severe slide near the bottom of the road.

To experience the Toll Road without going through Eaton Canyon and past the slide means dropping down from Mount Wilson. Although this is a fire road all the way, it is rough and quite steep in places. The ride is therefore best suited to later in the day rather than trying to climb out in the late morning. Due to the limited shade, it’s also best done in the fall or spring time (assuming there is no lingering snow)

Getting there

From Highway 2 proceed to Red Box (~14 miles from the 210 freeway exit in La Canada Flintridge) and turn right onto the Mount Wilson road. Continue to the summit and a one way system. If the gate to observatory area is open, continue past the gate on park in the large parking area, otherwise park in the limited space outside the gate. Google directions to start


The Ride

If starting in the observatory parking area pass back through the entrance gate and immediately turn left towards the gated fire road to the South. After passing under/around the gate the paved surface quickly transitions to dirt. You are constantly presented with excellent views of the San Gabriel valley and possibly the whole LA basin if weather conditions permit.

At approximately 1.23 miles bear left; the road on the right leads to Mount Harvard. The descending continues all the way to Henninger. Follow the road to the left at 5.76 miles (going straight leads to the heliport), and after passing by campgrounds (closed) the fire station and associated builds will be reached at 6.5 miles, after approximately 38 mins

There used to be a mueseum in the large building, a fire station and a nursery, all of which appears to be abandoned now. The campgrounds are closed to overnight use, you are likely to see hikers here resting after trekking up from Eaton Canyon.

The return is quite a tough climb so be sure to allow enough time. Aside of one hiker near Mount Wilson I did not see any other users on the fire road trail (or fresh tracks) so be sure to carry enough tools and supplies to be self sufficient.


Ride log

Last Ridden


Pedal Time

Elapsed Time

Oct 12th, 08

Good - fire road is maintained and better than I remember it from 2004, but still rough and steep in places

2 hours 1 minute

2 hours 30 minutes






[Directions to start]

[Map in pdf (646 KB)]

[GPS Trace (waypoint every quarter mile)]

[GPS Trace (all waypoints)]

[Topo file (.tpo)]

[Photo Album]





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Site Last Modified: Tuesday, March 10, 2009