South Ridge - Red MountainI wanted to write a quick report to add to the main description which is pretty sparse in information and I think leads to a much longer hike than necessary.
Park at the PCT Trail head off of exit 52, right after you get off the exit before you turn right up to Alpental is a right turn into the parking lot. You'll need a Northwest Forest Pass to park there.
Around 20 yards up the trail is a sign that says "Most Difficult", just beyond this on the left is slightly overgrown but noticeable boot path. If you come to the next sign for the PCT a few yards beyond you've gone too far.
This abandoned trail is very well maintained. It climbs up into the Commonwealth Basin and crosses the creek three times. At the end of the basin the trail begins to switch back up the ridge. The trail turns west (left) and crosses a gully and then climbs a bit more and levels off. Here you'll see the trail split. The left goes to Red Pond and up to Red Pass. The right is one of the many boot paths that leads up onto Red Mountain. The path is distinct in places and becomes less obvious off and on. I wandered back and forth off and on the trail. There is no real wrong path to the summit but you'll want to stay to the left on the south ridge.
Going this route its only 6.15 miles round trip, significantly shorter.
Make sure you take a helmet unless your the first up and down as there is a lot lot of loose rock on the slopes of Red.
Route on Google Maps