On highway 20 cross the Columbia River East of Kettle Falls at Barneys Junction. Left would take H20 to Sherman Pass and Republic. Instead go right on 395. Pass the Barstow store and in a few miles the Boulder Highway goes to the left just after a railroad overpass.
Here are directions to the Taylor Ridge trail: From the south side of Boulder Pass bike up the trail or road about 3 miles and go left on the road. Up that road about 3 miles and down a ways to a road that goes left and should have a sign for Taylor Ridge. In about a half mile it will turn into single track. Three miles down to Bulldog Cabin road. Go left on the gravel road a little over a quarter mile. There is a camp on your right and a trail sign. Take the trail down about 3 miles where it crosses an old road. You will find the last section of the trail almost straight across. It is still rough in places but ok if you walk your bike a few times. When you come out on the South Boulder road go left and in 3 miles of easy downhill you will come out on the Boulder highway. The road follows the large creek and has pools big enough to swim.
The trail goes from a high point of about 5800 feet to about 1800 at the pavement.
There are a number of other ways to do this trail and make it easier or shorter.
A good way to do an easy bike and then a hike is to park on the left at a big pullout almost 2 miles up Boulder highway. Take the S Boulder road over big humps and a bridge. Then it is a gentle uphill on a gravel road that was closed in 1997 after flooding. Go 3 miles and when you pass the next set of humps and fence you are close. Look for a road to the right with a small forest service marker with a number (178 ?) The trail starts a few hundred yards up this road.
Hardcore bikers could bike up the trail. You will gain a lot of elevation.