How to get there:
Locate the small village Tehachapi on Hwy. 58 running south-east from Bakersfield to Mojave. From LA, one can drive I-405 then fork east on Hwy. 14 to Palmdale. Continue past Palmdale to exit 61, Backus, drive through an impressive wind-mill farm (many hundreds of them), then enter Tehachapi. turn left on Hwy. 202 and continue to a local hilltop where a road forks left, signed for Tehachapi Mountain Park. Enter the park and follow the road as high as it get. Park here. This location is N35.06585, W118.48260, elevagtion about 1825 meter.
One first climbs Tehachapi Mountain, see the description there. Next, traverse to Double Mountain. The best route is to descend (right) and get to a small col on the connecting ridge. You bypass the small hump following a small trail on the right side. Continue on easy ground down the main ridge, as it levels, head right and find a forest road at location N35.04171, W118.49351, elevation about 2210 meter.
This road can then be followed to the summit.
There are two summits, both listed with the same elevation on the map. The first one has an open clearing with good views. It is hard to see details across to the other summit because of vegetation.
The second summit has several antennas and a few small buildings. However, the highest point is on gras and it can be accessed by making a small detour (left) to avoid the buildings.
Leaving Westwood early, I had a nice drive via Palmdale and arrived at the trailhead around 0815. Ready to hike by 0830, it took me an hour to reach the summit of Tehachapi. After a break there, I descended towards Double and soon realized that the connecting ridge was further across right. I angeled that way, but decided to bypass the ridge taking a somewhat lower route, then regaining the connecting ridge close to the slopes of Double Mountain. This plan worked well and I connected to the road, then followed it to the top, arriving there at 1045, just about an hour from Tehachapi.
After a nice break, I walked over to also visit the other summit. This one less nice with antennas and general, unfriendly signs about keeping out. I subsequently returned, this time following the road a bit longer, then walking up along the connecting ridge, only bypassing the small hump on the left side.
The return hike to Tehachapi took 50 minutes, the subsequent descent back down to the campground another 40. This was overall, a very nice hike with a bit of variation along the way.