Heading south on Mosquito Lake Rd, just after crossing Porter Creek, watch for the logging road on your left. If you come to a large dirt pit on your left, you just missed it.
Start up the road which will begin climbing immediately but will level off after the first 2 miles or so. Note that there are mile markers at almost every mile. Stay right at all intersections until the intersection at 5 miles, just after crossing Clearwater Creek, where you'll take a left, it is marked with a Forest Service 38 sign.
The road will climb again, and again stay to your right at all intersections. Cross a couple more bridges as the road climbs and flattens, climbs and flattens. Soon after 11 miles you'll see a sign for Elbow Lake
where there is a large parking area.
Continue on as the road climbs again. At about 12.5 miles, you can continue straight to a large parking area with access to Ridley Creek Trail
or just before that you can start up the switchbacks. This part of the road is 4WD only and becomes more of a trail than a road as it starts climbing over 300 ft per mile and up to 500 ft per mile by the end.