Oh my favorite subject...I couldn't care less about the "longest" climb, but the most challenging. Is there any more satisfying feeling in mountain biking than heart and legs on fire, sweat permeating your skin, heaving the air in and out of your lungs, while maintaining total control, exercising your skill and clearing the tech ? Meanwhile your buddies are put to the foot like a common hiker carrying their Ira Spring guidebook ?
Honorable mentions-
Kachess Ridge - no warmup, straight kick ass out of the gate, good pitches, good tech, can be very condition dependent, but you're up on the plateau pretty quick making it a bit too short to be ranked higher.
Craggy Peak - sandy, motorcycle trench trail complete with rubber flap water bars, but again the steep section is too short and the misses have more to do with the flurry of punches rather than sheer knockout power. I might not even include it if I hadn't just rode it last month.
Merrit Lake - A classic, not overly steep, but a root killer. Almost too many offs though, and again a bit short. Never really gets steep either.
BlackRock(?) creek trail to the backside of Esmerelda lake - Just plain f'in steep and tough, I don't have too many more superlatives for you on this one, just a hard , tough, barely moving the pedals around pull.
Anacortes - too many too list, but especially coming up towards Erie on the Igor route. This is the only local place where you can work on your climbing skills that I can think of.
Preston's secret September ride - sorry, can't tell you about this one, but its just one big trials move after another up root and rock ledges.
Blanchard Mt coming up from Chuckanut - I guess this is one more local place to work on your climbing. Not super duper hard, but steep and tough. Bonus is lots of hikers many from the uh, local college, who will be amazed at your athletic grit. Which, combined with $5, might buy you a latte.
Serious challenges
Angel's Staircase Horsehead pass - Riding to Cooney Lake is just long, and up to the top is mostly carrying. But the last climb out of Boiling Lake to Horsehead pass - Loose shale means loose traction while trying to mo' your way through the same shale rock garden terrain. Throw in a steady pitch and a few extracurriculur tech challenges not to mention the overall fatigue at this point and you have one hardcore climb.
"Artifacts/TMT approach" - This one is only a few hundred feet gain and a few 100 ft linear, with very little challenges, but the pitch, the trench, the undulations makes it very very difficutl. Very conditions dependent- a few years ago it was not cleanable at all, and then something changed in its composition and it can be ridden when your monthly man cycle is at its peak and the earth is loamy. If you are a good, well behave biker, you shouldn't even know where I'm talking about.
Lower Dungeness - mostly pitch climbing and almost always wet and soft. Just when you think you're done it comes back to slap you down. If you can ride this whole climb with no dabs (other than pure washouts) then consider yourself a climber. Some of the top is classic, pitch, pause, pitch, pause, we're done, NOOOOOO, steepest pitch of all !
Miller Peak CW - The lower part just beats you up and steals your mojo as you delightfully meander your way through the woods encountering short but very loose shaley climbs that are steeper than they look. You are already losing it when the serious stuff starts - Steep, mostly unrelenting, and shaley and loose, it takes the fortitude of a Banzai squad to stay on your bike and keep the pedals turning. I've never been fully satisfied on my performance on this one, probably because its traditionally an early season ride. I'm not sure why this one doesn't make it into the top echelon, but its just missing a certain je ne seis quois.
The killers -
Goat Mt (St. Helens) - I believe something has changed in the upper trail composition, looser, more trenched out. The last time I cleaned it was probably 10 years ago, I pretty much just heart attack out on the last bit these days although its been a few years since I've been up it. STarts with pumicey energy sucking looseness until you get in the woods, and then excellent trail tread means great traction but every pitch just gets steeper and steeper to the top. A total F'in redline, and if you're going up it you probably have lots of miles to cover when you're done.
Tumwater Mt Lollipop of Woe (St. Helens) - This comes after Goat Mt, you end up down in a Shire like woods following a little creek. And you climb, and you climb, and you climb - pitch, tech, horse pock bump trail, it has a little bit of everything. Inspired my favorite ride report ever, back when we still wrote those things (
Yahoo! Groups).
The winners -
Copper Butte (Kettle Crest) - This butte rises up out of the Crest like a hideous giant boil on the face of a cartoonish Hollywood villain in the final stages of his self inflicted demise of madness. It only takes about 40 minutes but its almost completely composed of sharp rocky shale with a relentless pitch. Total red zone climbing where every bit of rock garden tries to throw you off your line. The last 500 vertical feet is just intense and yet its totally rideable.
Juniper Ridge- The whole damn thing. Its all climbing, every type you want - sandy moto trench trail, woodsy steep pitch root ball, rocky shale sidehill single track, smooth no tech steepness, sun exposed death march push. This ride will re-energize your zest for life ! Or, you could just walk I guess.