Road Canyon Trail makes the ascent from West Side Rd (FR 90) gently, then steeply up to the Sacramento Peak area, bringing you to the Sunspot Installation, complete with visitor center that is open most of the year providing information, gifts, food and drink. Additionally, there is a walking tour of the installations.
The guide book for the area designates the lower end of this trail in Road Canyon as 234A... yet, it would be more correct to assign the spur section that drops over and out of Road Canyon, heading for Dog Canyon as 234A instead of as the bottom of 234, Road Canyon Trail. Confusing? The Forest Service, wanting to create a "simple" path to connect down to Dog Canyon trail, moved the official designation of Road Canyon trail over to the spur, renaming the bottom of Road Canyon as the Spur. I'm waiting for the new trailhead signs to see if this designation holds. But, since this is Road Canyon Trail, I feel it makes the most sense to stay with the Road Canyon trail remaining in Road Canyon. Basically, the portion of the trail that is all in Road Canyon is 2.3 miles, starting off softly rising to 8300' over the first 1.4 miles, then steeply climbing to 9100' over the next .9 miles. At that point you are at the official upper Trail head. From there, you turn left and follow the old road around and up to the Visitor Center on Sacramento Peak.
If you wanted to hike the 234A Spur, it intersects the trail at that 8300' point at 1.4 miles. It drops steeply down to West Side Rd, losing nearly 600' in .7 miles. Nice loops can be created using the spur trail and West Side Road.
This narrow, little used trail is a very pleasant mix, with narrow, winding paths along heavily forested canyon walls, then down and through meadow like areas fed by perennial springs.
The Forest Service has recently (2010) begun a process of setting up prominent Trail Head signs along West Side road... if they include Road Canyon, I would expect this great little hike to become much more popular. Till then, it remains a hidden gem.
You may obviously hike this trail from the visitor center instead of West Side Road. If you do, simply head out from the parking area to the south, through the barb wire fence and down through the pine/fir forest to intersect the old road, following it around to the marked trail head just down the hill. There is also a gate in the fence; if desired, follow the fenceline to the west, the gate is at the first corner pole.