The Mail Ridge Tower Link-Up is a fantastic route linking some superb 5.10 pitches on the West Ridge. Steve Levin gives it 4-stars in his latest guidebook and I can't say that I disagree. While there is some junk thrown in the middle for good measure, the hard climbing is spectacular and is very well protected.
P1: 5.10c, 80'. Begin with Chick On The Side (which lies just below the start to Handcracker Direct). This pitch begins in an obtuse dihedral next to a pine tree. A good landmark is the fixed pin and chalked rail at about 25'. Stems, good locks, and some funk will bring you to the top of the dihedral. Stay true to the dihedral or step right after the crux. Either way, make your way up and belay after 80'. Move the belay left roughly 30'.
P2: 5.10c, 110'. This pitch is the first pitch variation to Mail Ridge. Start up a right-facing corner on good sidepulls and locks. The gear is great here. Fire up through an overhang using some underclinging trickery to a good stance. Follow easier (5.8+, 5.7, respectively) corners to a tree belay. There are rap rings around the tree. It should be noted that while the hard climbing is protected well enough, there are some spots above the crux (gaining the 5.8 corner) that are somewhat dicey. Small cams work well here. Also, on the day of our ascent there was a fixed nut at the crux that protected it very well- I would advocate to leave this in place as it makes protecting the crux that much easier.
P3: 100', 5.5. Climb the scrappy chimney and blocky terrain to the belay at the base of the magnificent looking splitter.
P4: 100', 5.10a. This is the final pitch of Handcracker Direct. Climb the obvious splitter to the top of the formation. This can be broken into 2 pitches (belay at the top of the crack if splitting into two) but is pretty easy to link if long slings are used to alleviate any rope drag. This pitch is fantastic and a very good pitch for the grade in Eldo.
The individual pitches don't necessarily warrant classic status, but putting them all together creates a really great route!
A double rack of Camalots or equivalent up to #2. A single #3 is sufficient for the last pitch of Handcracker Direct.
As of March 6th, 2014, there is still a fixed wire on the 2nd pitch. I would recommend using runners on all gear above the crux as there is a rope eating flake at the top of the 5.8 corner. Still a great route, too!