The main crack at Beaver street is rated at 5.9 not 5.10b. Having climbed it several times and seen 5.9 climbers make it up (with a fall or two), I think the 5.9 rating is about right on.
The book "Bay Area Rock" lists this at 5.9. I'd have to agree. Good footwork eases the rating. It's a delightful route! Past the crux, there is a section so glassy that you can check your teeth for poppy seeds. While the top section eases up a lot, the view is great.
I freed this crack last month and found it not to be that fun. The face of the rock is extremely polished and thus slippery. Next I aided it and I thought it was great aid practice. A2 I guess.
I just climbed this route today and its given a 5.10a rating in "Rock Climbing the Bay Area" and is a great little climb. First time up, a beginner like me had to use my arms a lot but was able to do it no problem and relaxed second time. Lots of fun and interesting rock.
Admittedly I was leading above my grade but I wished for some #00 cams. Don't think I used anything above a Red (#4) TCU. Not too shabby for being in the middle of the City. Good stuff
I think there might be some confusion between this route and Crack Direct. In the Bay Area climbing book, Crack Direct is rated at 5.9, while this route, The Crack, is listed at 5.10a. Both of these difficulty ratings seem reasonable to me.
Loose at the top. Have your belay partner stand back a few feet.
Lead is possible (bring the small stuff) but I wouldn't recommended it.