PBP is a relatively easy ride. There is nothing that is steep and long. There are a few short steep pitches but nothing you can't muscle up if you need to. Gearing is a very individual thing but people have been doing PBP since the late 1800's on all sorts of bikes so I don't think gearing is that critical on that ride. Heck, in 2003 a guy did it on a push bike...what kind of gear did he use??? If you were doing a ride like the old BMB gearing would be another matter altogether.