At the foot of the San Gabriels, Caltech has excellent access to plenty of steep, challenging trail runs. Of course you could hike them too, if you're into that. Below some of the best runs that are closest to Caltech (within about an hour) are summarized by region and suggested parking lots. For kicks, a 1 to 3 star rating is given.
San Gabriels Front Range
Windsor Ave/East JPL parking lot
Only about 15 min from Caltech, this trailhead gives excellent access to a number of nice loops above JPL and around Hahamonga Watershed Park. The parking lot is on the east side of Windsor Ave. where it meets Mountain View St., just before the entrance to JPL. A few suggested runs/loops follow.
- Gabrielleno/Waterfall trail (8.5 miles; 1000 ft gain; **)
One of the flattest, yet most scenic, trails in the area, this ~8 mile out and back follows the Arroyo Secco up to the waterfall created by the debris dam. The Gabrielleno Trail continues past the dam, but only to the Ken Burton trail (see below). Beyond this point the trail is closed (overgrown and not particularly enjoyable).
- El Prieto/Brown Mountain Loop (8 miles; 1700 ft gain; **)
This 8 mile loop (really more of a lolly pop) heads up the steep but fun El Prieto trail (watch for mountain bikers coming down), climbs up Brown Mountain fire rd. and makes a nice, fast descent down Fern truck trail.
- El Prieto/Lower Sunset/Pipe Trail Loop (8 miles; 1300 ft gain; **)
Also about 8 miles, this loop heads east at the top of El Prieto, dropping down to Millard Camp. From there, a nice, short climb on Lower Sunset brings you to the top of Chaney Trail (a road!). Heading south for a short distance on an unmarked dirt road leads to a steep but runnable trail with an exposed pipe (I call it the pipe trail). A mile and a half on roads brings you back to near where you started.
- Brown Mountain/Ken Burton Loop (14 miles; 3000 ft gain; ***)
Never too steep, but remote feeling, this 14 mile loop is one of my favorites in the San Gabriels. A healthy, but not-too-steep climb leads up past Brown Mountain saddle, then up to the shoulder of Brown Mountain itself. From here the Ken Burton trail drops steeply to the riverbed of the Arroyo Secco. The trail follows the sandy riverbed south for about half a mile before hugging the west (right) side of the canyon for a quarter of a mile, then cutting back across and climbing out of the canyon on the east (left) side to go above the debris dam. A steep drop brings you down to the Waterfall trail, 4 miles from where you parked.
- Rose Bowl Loop (7.5 miles; 500 ft gain; *)
This run definitely isn't in the San Gabriels, but it can be easily access from the same parking lot (as well as many others). Running around the Rose Bowl is very popular, but you'll miss a lot of the people if you stay on the decent trails that go most of the way around it. Add in some trails in Hahamonga Watershed Park (the dustbowl above the Devil's Gate Dam) and it makes for a pretty flat, pretty fast about 7.5 mile run mostly on trails.
- Flint Canyon/Cherry Canyon/La Canada Trails/Gould Canyon Loop (10 miles; 1000 ft gain; *)
Again, not in the San Gabriels but easily accessed from Windsor, La Canada has a number of trails that can be connected in a pretty nice residential-feeling loop. This loop can be nice when you're afraid of mountain lions in the San Gabriels. From the Hahamonga Park (the dustbowl), Flint Canyon leads through neighborhoods to Cherry Canyon, which surrounds Descanso Gardens. A steep climb up Cherry Canyon brings you to Descanso Mtwy (and nice views of the San Gabriels). Following Descanso Mtwy to the west/north, you'll eventually drop down near Descanso Gardens and can take the Cross Town trail either all the way up to the south face of Mt. Leukens or cut across on roads to Gould canyon (I've shown the later here). Gould Canyon follows channelized rivers back to the dustbowl, which you can cut across to get back to your car. This makes for a 10+ mile run.
Parking in Millard Camp gives an alternative access point to run listed above and below. There's an upper and lower lot and an Adventure Pass (or National Parks pass on your dash) is needed to park in certain areas. Also this area is gated before 6 am and after 8 pm or so. it's also about 15 min from Caltech.
- Sunset Ridge Loop (5 miles; 1800 ft gain; *)
The most obvious loop from Millard is to run up Sunset Ridge, then return on the paved fire road. While not amazing, it's still pretty nice. You could add on a couple miles by starting at the lower parking lot.
- Brown Mountain Loop (15 miles; 4750 ft gain; **)
This adventurous loop has a bit of mandatory hiking with some light bushwhacking, but the running on the fire roads is fast and the views are pretty good, so I think it's worth it. From Millard Camp, fire roads lead to the shoulder of Brown Mountain, where the Ken Burton trail drops down. Instead, follow a faint trail steeply up Brown Mountain's ridge. Often the trail is visible, but sometimes you just have to push through the bushes, which isn't as bad as it sounds. After reach the large summit of Brown Mntn. the trail improves but becomes quite rocky as you follow the ridge towards Mt. Lowe. Surprisingly, you still have some pretty big climbs left as well. Running down Mt. Lowe Railroad is fast and brings you back to Millard Camp. You could make this run a bit longer by starting at Millard Camp, or you could shorten the trip by starting up Mt. Lowe Railroad and coming back the same way.
Top of Lake Ave
Parking at the top of Lake Ave. (also about 15 min from Caltech) puts you at the start of the popular Sam Merrill trail which leads up to Echo Mountain in about 3 miles. While heading going out and back on this section is probably the most popular run and hike, a few longer loops are included below.
- Sam Merrill/Sunset Ridge/Pipe Trail Loop (9 miles; 2750 ft gain; **)
Cutting left (west) towards the top of the Lower Sam Merrill trail takes you across a nice connector and onto Mt. Lowe Fire Rd. From here, either continuing down the pave fire rd. or down the steep and windy Sunset Ridge trail brings you to the top of Chaney Trail (a road!), which is above Millard Camp. Heading south on an unmarked dirt road that quickly turns into a trail with an exposed pipe, you'll drop quickly down to Loma Alta Dr. which will lead you back to your car in a few miles for a nice about 9 mile loop.
- Sam Merrill/Mt. Lowe Railroad Loop (11 miles; 4000 ft gain; **)
Continuing up the Sam Merrill past Echo Mountain yields almost another 1000 ft in elevation gain on squirrely trail. The reward is a long drop down Mt. Lowe Railroad, a nicely graded fire road. From Mt. Lowe Railroad, you can drop down Sunset Ridge (as above) or go back down the Sam Merrill trail (as shown here). Running up Castle Canyon provides a (steep!) alternative to the Upper Sam Merrill trail. However you do it, it's a challenging 11+ mile loop.
- Sam Merrill/Mt. Lowe Loop (14 miles; 5000 ft; ***)
An even more challenging alternative is to continue up Mt. Lowe Railroad to the relatively craggy top of Mt. Lowe before heading down the Mt. Lowe Railroad. I've wished I had gloves up there on a cloudy summer morning.
- Sam Merrill/Idlehour/Mt. Wilson Toll Rd. Loop (17 miles; 5200 ft gain; **)
A longer option is to take the small Idlehour trail from the 4-way intersection at the top of the Sam Merrill trail. This trail drops down into the nicely wooded Deer Park Branch of Eaton Creek and then climbs steeply up to the fast Mt. Wilson Toll Rd (no toll required these days). At the bottom of the Toll Rd. you can either take roads or a pretty steep trail, as well as a sneaky connector through Los Flores Canyon back to the top of Lake Ave. Altogether a pretty badass loop.
Eaton Canyon Trailhead
Eaton Canyon Nature Center (again, ~15 min from Caltech) provides another access point to the Mt. Wilson Toll Rd. There is also a gate off Pinecrest Dr. that cuts off the lower Eaton Canyon Wash, but is locked from sunset to sunrise. In addition to the run below, other loops listed above could also be started from here. A short (3 miles round trip) run/hike up to Eaton Canyon falls is also possible.
- Henninger Flats Out and Back (7.5 miles; 2200 ft; *)
The best run from here is up to Henninger Flats and back. There's a campground at Henninger flats, some nice views, and a surprising number of pine trees for the San Gabriels.
- Altadena Crest Trail to Gooseberry Motorway (6-8 miles; 2200 ft; *)
The Altadena Crest Trail doesn't go especially high, but it has a lot of ups and downs as it traverses the south side of the mountains, making for a more interesting run than Henninger Flats. I measured about 6 miles from the Pinecrest entrance to the Gooseberry Motorway loop; starting from the Eaton Canyon Nature Center should add about two miles. You can also continue past Gooseberry towards Echo Mountain.
Bailey Canyon Trailhead
This trailhead in Bailey Canyon Park is about 20 minutes from Caltech. When the park is closed, you may have to climb through/over the fence to reach the trailhead (which appears to be accepted as standard practice by the locals; I even spotted elderly hikers squeezing through a hole in the gate).
- Bailey Canyon to Jones Peak (6 miles; 2500 ft; **)
A pretty steep trail with lots of switchbacks, calling to mind the Sam Merrill trail at Echo Mountain, but with more trees and fewer hikers. There are a few side trails, but you can stay on the route by following your intuition at every fork: always take the steeper upward path.
Mt. Wilson Trail
Tucked into a neighborhood in Altadena, this steep trail quickly feels remote and gives a 'fast' way up Mt. Wilson. It's about 20 min from Caltech.
- Mt. Wilson Loop (22 miles; 6400 ft; **)
A challenging loop is to head back down the Mt. Wilson Toll Rd. From there, running through Eaton Canyon wash and getting back to your car via a few miles of flatish road. The parking lot on Mt. Wilson is gated until 10 am, but there is a sneaker around the gate which is shown in the route.
Chantry Flat is a bit further into the mountains and a bit further from Caltech (about 30 min), but makes a good start to a weekend run. Trails are much more wooded here and a number of excellent 5-20 mile loops are possible. Parking requires an Adventure Pass or a national parks pass on your dashboard. Parking fills up early, so try to get there before 7am for a decent spot.
- Winter Creek Loop (5 miles; 1500 ft; ***)
A nice 5 mile loop is to head up one side of Winter creek, cross the creek at Hoegee Campground, then head down the other side.
- Mt. Zion Loop (9 miles; 3000 ft; ***)
A bit longer (~9 mile) loop heads up Mt. Zion and then follows the nice, shady Santa Anita Creek back to Chantry Flats. Along Santa Anita Creek, the trail splits with the low path going close to Strutevant Falls.
- Mt. Wilson to Rim Trail Loop (16 miles; 5200 ft; **)
From Chantry Flat it is also possible to run up to Mt. Wilson, an almost 7 mile climb. From here the Rim Trail (longer, ~16 miles) or Strutevant trail can be taken down to the Santa Anita Creek, which leads back to Chantry Flat. A challenging, excellent run.
Almost an hour from Caltech, Mt. Baldy is the tallest mountain in the San Gabriels and has a very alpine feel. I've only included the one run I've done, but a number of shorter (or longer!) loops could be done, especially using the relatively gently graded Baldy Rd (dirt). Adventure Pass or National Parks pass is required to park. Very busy on the weekends.
- Bear Canyon to 3 Ts Loop (18 miles; 7500 ft gain; ***)
This burly loop has a ton of climbing, leaving me hiking most of the uphills. Nonetheless, the downhills are fun and the views are great, both along the Devil's Backbone descent from Mt. Baldy, and through the large bowls of the 3 Ts trail. When the lodge is open, you can get water and use the restroom inside.
- Icehouse Canyon to 3 Ts and Baldy Notch (9.5 miles trail + 3 miles road; 4600 ft gain; **)
A shorter alternative is to start at Icehouse Canyon and take the 3 Ts trail counterclockwise to Baldy Notch, then come straight down to the notch parking lot. The last couple miles require going along a paved mountain road, which can be scary due to fast cars. The notch is pretty popular so it might be possible to get a ride back to Icehouse Canyon.
San Gabriels, Hwy 2
Heading up Hwy 2 leads to a number of nice runs higher in the San Gabriels. These runs are typically 30-60 minutes from Caltech, but getting to a higher elevation and avoiding people can be worth the drive on the weekend.
Mt. Josephine/Strawberry Peak
Some of the first nice trails you come to Hwy 2 are at Mt. Josephine and Colby Canyon, giving access to Strawberry Peak. Adventure Pass or National Parks pass is required to park.
- Mt. Josephine Out and Back (8 miles; 2300 ft; *)
This out and back up the Mt. Josephine fire road has some decent climbs, but they're never too steep, and you get a nice panorama at the top.
- Strawberry Peak Loop (14.5 miles; 4000 ft; ***)
Just up Hwy 2 from Mt. Josephine fire Rd. is Colby Canyon. This steep trail leads to the saddle between Strawberry Peak and Mt. Josephine. Running around Strawberry Peak gives some great views and takes you through the wooded Strawberry Meadow. From here you climb back up to the saddle between Strawberry Peak and Mt. Lawlor. A nice, windy trail drops down to cross the 2 at Redbox (water fountain!) and a bushy trail follows the Arroyo Secco down to Switzer Camp. From here it's just a short distance on the 2 back to your car. A remote and awesome loop. You can make it a bit longer by starting at Mt. Josephine fire road.
Further up Hwy 2 you come to Redbox on the right (~40 min from Caltech). From here a few trails follow the San Gabriel river making for some pretty nice loops. Adventure Pass or National Parks pass is required to park.
- Gabrielleno/Redbox OHV Loop (9 miles; 2200 ft; *)
Follow the twisty, shady Gabrielleno Trail down from Redbox along the San Gabriel river for a few miles, cross the river, then head back up it on the OHV road. While the dirt OHV road isn't awesome, it makes a decent loop.
- Gabrielleno/Mt. Disappointment Loop (8 miles; 2700 ft; ***)
A steeper but nicer loop leaves the San Gabriel River at Valley Forge Camp to climb up to the Eaton Saddle. After cross the Mt. Wilson/Redbox rd and going through the tunnel on Mt. Lowe Railroad, the loop climbs up Mt. Disappointment. A steep, fast single track (or alternatively a fire rd) brings you back down to the Mt. Wilson/Redbox rd near Redbox. You can make the loop a bit easier by heading down the paved Mt. Wilson rd to Redbox instead of crossing it and running up Mt. Disappointment.
- Gabrielleno/Mt. Wilson/Mt. Disappointment Loop (11 miles; 3500 ft; **)
You can make the above loop even longer by continuing along the San Gabriel River to the Kenyon-Devore Trail, which leads to the top of Mt. Wilson. A mile or so on pavement brings you down to the Eaton Saddle.
Driving up the paved Mt. Wilson/Redbox rd from Redbox brings you to Eaton Saddle. This is a nice way to get great views over LA and of the relatively craggy peaks surrounding Mt. Wilson. Adventure Pass or National Parks pass is required to park.
- Mt. Lowe Loop (5 miles; 1700 ft; **)
A nice loop is to run around Mt. Lowe from Eaton Saddle, climbing up to the airy summit, dropping down on the its south side, then using the Mt. Lowe Railroad to climb back to Eaton Saddle. There are a few trails around Mt. Lowe, so there are some options. Avoid the temptation to check out the nearby Tom Sloane trail that's on Google Maps. It's eroding shit.
Almost an hour from Caltech on the west side of Hwy 2, the Chilao area offers some nice loops through pine groves and chapparal hill slopes with less elevation gain than lower in the San Gabriels. Adventure Pass or National Parks pass is required to park.
- Mt. Hillyer Loop (7 miles; 1200 ft gain; ***)
A nice loop follows the Silver Moccasin trail to Horse Flats Campground, and then cuts up through the golden granite boulders to the flat top of Mt. Hillyer. Following a forest service road back down to Chilao gives a quick descent and nice view of Alder Canyon.
- Mt Hillyer/Sulfur Springs Loop (11 miles; 1800 ft gain; **)
A longer option is to make a loop with the PCT towards Sulfur Springs, then head down the Mt. Hillyer Trail.
- Chilao to Altadena (30-40 miles; 18,000 ft gain; 13,000 ft loss; **)
With a long car shuttle, it's possible to link trails from the Chilao area all the way back to Altadena, making a 30-40 mile run that is more down than up. The route shown basically follows the AC 100 course, with some modifications to get the desired distance. There is water on top of Mt. Wilson, but I also stashed water on Hwy 2 at Shortcut Pass for this run.
San Gabriels, Hwy 39
Driving up the 39 from Azusa leads to a few nice trails about 30-45 min from Caltech. Water flows in the San Gabriel river almost year round, which makes it a pretty nice place to run or even swim (aside from the masses hanging out in the river).
West Fork of the San Gabriel
Park on the east side of the 39 and cross to either the paved trail that follows the West Fork of the San Gabriel, or the OHV road just down the 39 from here. Adventure Pass or National Parks pass is required to park.
- West Fork of the San Gabriel Loop (29 miles; 7000 ft; ***)
A nice, relatively easy, almost 30 mile loop can be made by following the Rincon-Redbox OHV road for about 15 miles before dropping down to the Cogswell Reservoir. From here, the paved Devil's Canyon Dam trail leads back to the 39. Despite the distance, the loop only climbs about 4000 ft. When I did this route it was in the 90s and I stopped a few times to dunk myself in the creek. Running out and back on the relatively flat paved trail is also nice (~16 miles out and back for the entire trail).
- Crystal Lake/Mt. Islip Loop (9.5 miles; 2700 ft gain; ***)
A beautiful ridge run up Mt. Islip, with great views on both sides, followed by an easy descent through the woods back down to Crystal Lake. There's a short section of pavement as you go through Deer Spring campground around mile 8 where it's easy to lose the trail; the trail reappears just past the picnic tables at the south end of the campground, on the right-hand side of the road.
San Gabriels, Big Tujunga Canyon Rd.
Taking exit 11 from I-210 and driving up Big Tujunga Canyon Rd. leads to several trails about 30-45 min from Caltech. Adventure Pass or National Parks pass is required to park.
Trail Canyon Trail
- Trail Canyon to Tom Lucas Camp (8 miles, 2000 ft gain; **)
Trail Canyon is a popular trail leading to a nice waterfall and swimming hole about two miles in. Continuing past the waterfall to Tom Lucas Camp is a bit overgrown, but doable. Frequent stream crossings provide plenty of spots to cool down. In principle one can continue on up to Condor Peak and Iron Mountain, but this requires serious bushwhacking through brambles and poison oak (don't try it in shorts).
I haven't run here, but there are trails and it's not too far away. Someone add some nice runs, please!