Going south from the pass is the Rainier View Trail.  It is in the Norse Peak Wilderness Area, so no cycles are allowed there, but it is only a short walk.
The steep six-mile road up was closed for several years awaiting repairs.  I made the climb twice in 2013 on the trike.  In 2014, the road was reopened without the repairs on a trial basis, but recommended only for four-wheel-drive and high clearance vehicles, although we had no difficulty in the Suburu Outback.  Your speed up or down will likely not exceed 10 mph.
From the pass, you can ride north on the Noble Knob Trail or branch off to other very challenging National Forest mountain tracks.
The unbroken grade has numerous switchbacks in its ascent.
Several portions of the Noble Knob Trail are singletrack.
It is easy to get lost in the network of alpine trails,especially when the weather changes, so take a GPS, extra batteries, and maps.
A narrow trail sometimes works better with a mountain bike, but the dropoffs that go from very steep to vertical can make a person nervous with only two wheels.
Noble Knob
If you stash your trike in the woods near Corral Pass or in your car if you drive up, you can walk a mile to one of the most breathtaking vistas in the  area.
The short Rainier View Trail starts at the pass parking lot and heads toward Castle Mountain and Pacific Crest Trail, which goes all the way to Mexico.