May 27 update: Stage 19 profile should send shock waves through the General Classification with a course shaped like a lollipop. Well, the stage profile looks like shock wave anyway; there are four categorized climbs with the first three getting progressively harder and then the first climb is repeated for the finish.

The first and finishing climb is to Aprica which has an average grade of 3.5% over 14 km, quite modest by Giro standards. It's the two climbs on the north side of the loop that will be decisive. Trivigno at km 130 is rated a cat 1 for its 7.6% grade over 11 km. The riders will descend the treacherous east side and immediately scale one of the hardest climbs the Giro ever uses, maybe second only to Monte Zoncolan which will be fresh in the riders' minds. Passo del Mortirolo is 12.8 km of 10% with a max grade of 18%. Its slope is about 2% less than the Zoncolan but the climb is almost 3 km longer.

If gaps haven't formed at Trivigno then they will on the Mortirolo. It is possible the top finishers from the Zoncolan stage (Basso, Evans, Scarponi and maybe Cunego) will go over first (among the GC contenders) with a good lead then work together on the descent before fighting it out on the long slog to the finish in Aprica.

This stage is very similar to stage 20 from 2008 except the stage doesn't carry on from Aprica with a descent into Tirano and Trivigno is substituted for Passo di Gavia which will (hopefully) be featured as part stage 20 this year. Back in 2008, Danilo di Luca was only 21 seconds back of the leader, Alberto Contador, going into stage 20. Di Luca was dropped on the Mortirolo and lost over 5 minutes by the finish. He also lost all hope of winning the race or even making the final podium. — Steve
Detailed Climb Profiles and Contour Maps — gazzetta.it
  3D Course Flythrough (01:00) — raisport.rai.it

More photos of the narrow, tight switchbacks on Passo del Mortirolo: