I'd heard about 'the zoo' climb before, but had no idea where it was - but lo and behold, somebody saved the route on my site, veloroutes.org! (as a side-note this is how I know the site is working - not just saving my own routes but discovering new ones!)
The climb is 2.5 miles long, and gives you over 1K feet of elevation gain! This is about twice as big as Tolt Hill Road, which used to be the best (or worst, depending on how you feel about climbing) local climb I knew about. Probably the hardest local climb excluding the mountain passes like Snoqualmie and Stevens.
The Ascent:
The first section of this climb is probably a good 10% grade, and it seems to fluctuate between 7 and 10%, but I'm estimating, so I can't be sure. My rear tire was skidding a bit going up, due to the dampness that was still on the ground and the steepness of the road! About half-way there's a small plateau of sorts to give your legs a rest, but once you turn onto 60th St the rollers start, and they seem to get steeper and steeper! Some of them towards the end must've been over 10%, at least it felt that way. Once at the top you can take a hard left and continue up the mountain for a quarter-mile or so, which I now call it the "bonus climb."
The Descent:
You might think that since this is such a big climb that the descent would be a screamingly-fast one, but it's not! The hair-pin turns force you to keep your speed way down, and I almost learned this the hard way: I was coming down the first hairpin, my bike started to drift more and more towards the guard-rail on the right side of the road, and the wet mold next to it! It's a scary feeling when you know you can't slam on the brakes due to the damp ground, and you can't do a hard turn 'cause you'll slip, so I just had to ride it through while tapping the brakes! I came within maybe less than a foot of the edge, and got to peer down the steep slope that probably drops a good 40 or 50 feet! Scary sight indeed. Next time I'm gonna go as slow as a snail around those turns!
The Views:
You might also think that being 1,100 feet above sea-level you'd be able to see the city and lots of cool sights, but you can't; there are lots of tall trees blocking most of the views! You can see Lake Sammammish pretty well, and the Eastside as well. Definitely puts 'hills' like those around Bellevue into perspective, that's for sure! The 'bonus climb' had a little clearing that gave a pretty good view of the Cascades, but that was about as good as it got.
To sum it up, this is a great climb, but don't get your hopes up about a fast descent - Tolt is better for that.