Pentaprance climbs the huge dihedral system on the upper SW face of the Third Flatiron, just right of Friday's Folly. We climbed it in one long pitch and one short pitch, rather than the 3 pitches shown in the Rossitter guide.
Pitch 1: Head up the obvious dihedral to a fixed pin. Do some mildly runout climbing on 5.9+ terrain to the first bulge/roof. Pull over the bulge, and continue up the corner on interesting and sustained climbing which is tricky to pro in places. Keep heading up till you pull through the second roof/bulge, and belay. This pitch is long, exciting, varied, and sporty in places, but never really too scary if you're solid at the grade.
Pitch 2: Traverse directly left on the steep face following the horizontal crack system, past two (or so) bolts/pins (sorry, it's been a while). The pitch is short but very sustained and technical, with poor feet and sloper hand holds along the horizontal. I thought it was perhaps 5.11a or possibly a little harder, in contrast to the guidebook rating of 5.10d. After a few cool moves, the climbing eases up and you traverse onto a big ledge at the top of the first pitch of Friday's Folly.
Keep going left to the end of the ledge and rap the last part of the standard Third Flatiron descent, which is right over Saturday's Folly. Very good route with relatively clean rock.
Protection
Standard rack with focus on smaller gear including nuts. Offset Aliens and plenty of long slings may be helpful too.
This was one of the first routes to be replaced when Boulder Mountain Parks, in their infinite wisdom, after over 4 years of negotiations with the Access Fund, deigned to allow local climbers to replace ancient fixed gear. The bolts were replaced by local climbers, not the ASCA. All that being said, its a great line and a long forgotten Flatirons route that certainly deserves a lot more traffic.
The bolts are good. I don't know if the 5.10d section deserves an S or not, but the lower section probably does. It's also hotter than tarnation and gets slick in the sun. Do it on a cool, shady day or suffer on the greasy slopers.