A rite of passage for aspiring long-distance hikers, the Pacific Crest Trail is a pristine wilderness path skimming the ridges of the Sierra Nevada and Cascade Ranges from Mexico to Canada. Its 2,638 miles overlook some of the continent's most spectacular scenery, from the purple deserts of Southern California to the snowy wilderness of the Okanogan National Forest. In between, the trail jockeys round Oregon's train of volcanoes: Hood, Jefferson, Three Sisters, and Crater Lake. You can hike, horseback ride and maybe even mountain bike it. But you can't ride a motorcycle on it. Not legally, anyway...

It's the nature of roads to go through mountain ranges, not along them. So shadowing the Pacific Crest Trail by road isn't easy. In Oregon, staying in the Trail's shadow means crisscrossing the Cascades by their numerous passes. To the east, in the lea of the range's imposing 10,000 ft.-plus peaks, the parched sandy soil and sparse trees bespeak a rain shadow. The rain, of course, falls on the sheer western slopes and in the mountains themselves. At elevation, the precipitation is often solid  -  it can snow here any month of the year. And does.

So it is that Ryan and I swing our Guzzis off Highway 26 just 57 miles south of Hood River into Mount Hood National Forest. We've climbed solidly from the Columbia, which cuts a deep gorge through the Cascades on its way to the sea. The broken cloud sitting in the valley coalesces as we climb, and, together with the trees, obscures our view of the mountains. We're soon doing the Biker's Rain Dance  -  those hopping, shimmying steps that go with struggling into reluctant raingear. National Forest Road 57 is a single-track ex-logging trail winding through the forest, squeezing alongside creeks and gullies.

We hit a stretch of gravel. Our map shows a paved way around, but the road has been emphatically blocked with huge boulders. We've no idea what treacherous conditions lie down that route, so the gravel road it is. It's easy gravel: fine stone on a firm clay base, so for five miles or so we rattle along in second gear, searching out where the gravel is shallowest. I consider the benefits a KLR would have on this surface, which makes the Le Mans feel distinctly squirrelly.

Hwy 57 eventually feeds into 224  -  freshly paved and tantalizingly twisty, though the surface is still too wet to exploit. This is high country and it's cold! I'm guessing we're over 5,000 feet because of the temperature  -  a good 20 degrees cooler than when we left Hood River that morning. We follow 224 to 46, a pretty, wooded highway hugging the Clackamas River, and, as far as traffic goes, we could be the last people in Oregon.

Going north again on 42, we climb to the tree line, and though Hood still lurks somewhere in the clouds, craggy buttes and rock faces shadow the road instead. Finally, back on the main drag, 26, we scan the road ahead for gas stations. Crawling around the forest loop has guzzled our gas, and the fuel light on Ryan's V11 has been glowing for miles. In rural Oregon, it pays to plan  -  most of the Cascade roads twist through National Forests where gas stations are rarer than spotted owls. This time we find salvation in Simnasho, a one-pump town on the Warm Springs reservation.

We've dropped maybe 3,000 feet into the Cascades' rain shadow. The climate change is dramatic. In just 20 miles, we've gone from clammy, bone-chilling rainforest to desiccated, treeless plain. It's canyon country: we follow the road across "the rez," sweeping up and down broad chasms that split the barren, brown terrain, and then rejoin 26 for a short hop along Pelton Dam.