The gate to the observatory is often closed and locked. Check for it to be open before driving to the top. Alternatively, one could ride up from Pasadena along the Mt. Wilson Toll Road and/or the Mt. Wilson Trail and avoid the gate.
The Sturtevant Trail is a quick descent from the Mt. Wilson Trail to the Zion Trail. Riders will start along a fence line near the Mt. Wilson parking area and picnic area. The head of the trail has a small plaque, so just keep an eye out for it.
Along the way, riders can expect to ride through a number of loose rocky sections, so use caution through them. In general, the trail is not very flowy, and you'll need to pedal occasionally. Additionally, riders should expect to come across some exposure. The trail is obvious so it would be difficult to get lost along the way.