I believe there's gotta be some out there. Ive been meaning to look around for some as its also a good way to get some reading practice in while looking at some nice bikes. If you can read JAPNZ, I would think that Mixi would also have some stuff as well.
ATM the only thing I can think of is PedalMafia

http://pedalmafiablog.livedoor.biz/

(Not 100% bikes, but...)