do it. have fun w/your bike. who cares what a few grumpy know-it-alls say on here. I've seen a few people put 650s up front and it looks mildly cool. I guess they do barspins that way, etc. The sky isn't gonna fall because you do something others on here have never tried. I'm sure people said it was dangerous to put a carbon wheel on your streetbike when that first started, too.