Southern California is an excellent place to mountain bike! The San Gabriels have numerous trails close to Caltech, most, unfortunately are very technical and learning to bike can be a challenge. People within the Caltech Alpine Club have rated them for quality (1-3 stars) and technical difficulty (numbers 1-3).
Windsor Ave/East JPL parking lot
The Windsor lot is at the end of Windsor Ave at the back (east) entrance to JPL. Get here by driving the 210 west (toward JPL and Caltech) and getting off at the Windsor Exit. Right right off the off ramp and follow Windsor until it makes a righthand turn at the JPL entrance. Park at the parking lot there, the ride starts here on approximately a mile of paved road.
- El Prieto Loop (7.8 miles; 1,243 ft gain; Quality **, Technical 2)
Singletrack with numerous switchbacks and stream crossings.
- Ken Burton Saddle Extension (6 miles round trip from the top of brown mountain, 1000 ft gain from the top of brown; Quality **, Technical 1+)
Ride up brown mountain road as for the El Prieto Loop, but once you reach the Saddle at the top of the Brown mountain road, instead of riding straight down to El Prieto, turn left and keep going up for 3 miles. You will reach another saddle, turn around at this point and either head all the way down the fire road, or do the El Prito loop)
- Brown Mountain
- Flint Canyon Trail
- Sunset Loop (8 miles, 2000 ft gain, Quality ***, Technical 2+)
Park at the beginning of Chaney trail or at Millard Camp and ride the steep paved road up until you see a sign for Sunset trail on the left (you will pass a left fork in the road about half a mile from the top, if the road turns into dirt and you see a sign for the cape of new hope you have gone about 200 yard too far). Take the single track down all the way to Millard and then ride back to your car. For a more technical uphill, from the bottom of Chaney trail you can ride over to Lake ave and ride up the lower sam merril trail.
- Monrovia Canyon Road (11.67 miles; 2,154 ft gain; Quality ***, Technical 1)
Mostly paved road. Unpaved trails are in excellent condition. Best in fall and winter time, but summer and spring early mornings are pleasant too.