[MENTION=339610]Darth Lefty[/MENTION], it's probably some random happenstance as to why 650b emerged above more likely sizes, and maybe there were some corporate wars over it. But it doesn't matter much. 584 is as good as 587 or 590 unless you are already invested in tires or rims in those sizes. I have nothing in any of those sizes (except for 590 on my three speed) so I'm not going into 650b any time soon. I plan to see if my 700c by 35mm tires work well on my Raleigh International. Probably.