Good jams above the smeary crux of the route. June...
Rattlesnake Crack is a White Rock classic. The crux is protected by small gear, which makes it a little scary, but the gear is solid. Difficulty has been variably rated from 5.11a to 5.11c in different sources.
Head up to the undercling flake. Place pro underneath the flake and traverse left and move up (crux). You're through the crux when you gain a sharp flake to shake out on. From here, most of the rest of the climb is 5.10. Climb up to a triangular roof, pass this on the left, and lieback up the steep finger crack to a stance on the prow. The crack continues as hands, then thins to fingers as the rock takes on the pocketed character of White Rock basalt.
A direct start in a seam 10' left of the undercling is 5.12, with not much for pro, if any.
You can identify this route from above by looking for the big flat rock at its base. From below, the clean face with the left-trending undercling traverse is apparent. It's also the next climb to the right of S Crack, the obvious S-shaped crack.
Nuts: 1 set, including RPs Cams: 1 ea. from TCUs to #2 camalot, with doubles of #0.75 camalot and #0.5 camalot recommended.
It's not a great route for toproping, because falls at the crux leave the climber dangling and unable to reestablish on the rock.
Photos of Rattlesnake Crack (aka Sidewinder) Slideshow
One of the coolest routes I've been on and a must do if at the Old New Place. Intriguing and challenging crux to a "thank god" hold; then a very fun crack from there on. Books I've seen rate this as "sandbagged 5.11b/c" for which I concur...with the sandbagged part.
One more thing: while it's true that when toproping this route it is difficult/impossible to get back on at the crux, one just needs to keep swinging and lower a couple feet to the large undercling. Granted, this doesn't allow for a complete hang-dog ascent because to move up you have to pull the moves - but that's why you're on it, right?