A dream route for any alpine rock climber: 850 meters of clean, excellent granite taking a moderate line up a classic north face. The long history and stunning location feed into the well-deserved aura around this climb. Despite the moderate technical grade, retreat would be nearly impossible and bivvying uncomfortable, so this is a committing climb.
Many additional trip reports and descriptions exist. Some of the best: summitpost.org/cassin-route/15...
A superb topo which saved us much trouble: stat.ethz.ch/~dettling/topo-ba...
Timing: if you leave the hut by 4am, can start climbing by 6am, expect to summit between 2 - 5pm. Plentiful bivy sites on the approach, so you can save an hour by camping out on the rocky approach.
Approach: Keep the ridge on your left and look for cairns. Eventually (~ 1.5 hr from hut, or 45 min from good bivvy sites) reach a steeper scramble up to a saddle 2550 m where the Nordkante starts.
Two short raps or downclimb to the ledge. Go all the way to the left edge, until some vertical rock starts. One pitch up (3a), and the "real" climb begins. I'm using the pitch numbers as we did them, more or less matches summitpost trip report.
P2-4 Rebuffat dihedral: obvious and stellar, 5a. Then easy simulclimbing to a belay inside an alcove (marked "belay before climbing gets hard" on topo).
P5 5c+ First harder pitch, delicate traverse straight off the belay, moving under a corner. Stays wet longer than other most pitches.
P6-10 Easier terrain, 3b-5b. Topo gives good guidance here. End up on the giant 'noon ledge', at a left-facing corner looking up at an enormous roof.
P11 6a The technical crux. Up the stemming corner, until almost exactly 25m when you turn right and move over the arete to the face. Very little to guide you, just have to keep moving until you reach the next left-facing corner. The two-bolt anchor will make you happy.
P13 5c+ My personal favorite pitch, up a corner to a roof, traverse around and keep going.
P16 V-chimmney. "5b" does not do it justice. Either slog through with one arm in the crack, or stem wide and trust your feet!
P17 5b second chimney pitch, fun and unique. No squeezing necessary!
P18-20 To the top!
Several ridge pitches will take you to the summit.
We abseiled the north ridge without incident, in 4hrs. If we had another day, we definitely would have gone down the Italian side, which is what nearly everyone does.
Northeast face of Piz Badile.
Bolted belays, many pitons and even some wooden pegs. Cams 0.3 - 3 all useful, nuts as well. Lots of manky old gear.