Aaron Waxman on 10/27/11
I followed sections 1, 2 and a little bit of 3 from Bellingham, WA to Hornbrook, CA before heading off route. The climbs were challenging, the descents were exhilarating and the snow capped mountains were stunning. Camping was also in some of the nicest spots I've been in.
The lack of traffic and remoteness of some of the sections through National Forests in the Cascades were serene and quiet. Another nice addition is that the National Parks are not traffic clogged in the way that some of the bigger parks can be. An added bonus is that the southbound route enters through the "back doors" of Mt Rainier and Crater Lake which are less traveled by tourists.
I'd recommend riding this route from North to South as the cyclists I met heading north said the beginning of their tour's in southern California were brutal while everything in Oregon and Washington had been a breeze comparatively. That said, the Cascades still offer long challenging climbs. Starting in the north will allow your legs to get used to the long climbs and give more time for the snow to melt in the higher elevations of the Sierras.
2010/11 was a big snow year which meant that some roads opened a bit later then usual. Check road conditions along the route before starting your trip.
If you like small roads, challenging climbs, incredible mountains and quiet wilderness camping the Cascades sections are for you.