I've thought of this as well and even went so far as to put 26" wheels with 55mm tires on my Karate Monkey as a proof of concept. There was nothing at all wrong with the resulting handling but it no longer rode like a Karate Monkey. It didn't even ride like a Troll, which was my hope. I think that much lower BB (compared to both 700c KM and a Troll) completely took away that nimble feeling that characterizes the KM & Troll. It basically turned my KM into a 26" touring bike.