Other than adding fenders or fat tire to your beloved tight-clearance road bike, I think the new 650B trend is a lot of hype. I can't remember where I read it, but there was an article about how 26" (559mm) wheels are too small and 700C wheels are too big, and 650B is just right, with a luscious yet still efficient ride. Give me a break. You can make changes a lot easily by changing tires.