The Sogn is an interesting beast, the most of which (to me at least) is that it can run both 700c wheels with cyclocross tires, or 650b wheels with monstrous knibblies. Rolling diameter-wise, 700x35 is the same as 650bx58.

This one is from the first Sogn breeding, and I've raced it in northern California and Oregon with both wheel/tire setups. I've found that depending on the course, the tire versatility is fantastic. Though, I don't know if USA Cycling would approve... I've been using it as a drop bar mountain bike when not racing it; the 650b monster-cross setup has been great for any terrain I can throw it at, except maybe big hit stuff.

Nerdy details
„ M/L Rawland Sogn canti frame
„ Selle San Something saddle (during race season)
„ XT hubs, Synergy rims, DT spokes
„ Sugino XD600 triple crankset
„ Crank Bros Candy SL pedals
„ Shimano UN54 113mm bottom bracket
„ Tektro long pull levers
„ Pacenti Neo-Moto tires (650b x 58mm)
„ Paul MotoBMX brakes (these allow the different wheel sizes)
„ Salsa stem, seatpost and handlebar
„ Ritchey headset and rear dropouts
„ SRAM PG980 cassette
„ XT chain
„ Paul cross levers
„ lots of mud, scratches and scrapes

More photos and info here: http://flickr.com/photos/gzahnd/sets/72157607364174687/

ĮGracias!