Re: which frame would be an ideal?
You should just go to a bike shop and look at the 24" and 26" frames. See how much clearance you'd have for changing wheel sizes. If you get a 24" frame and want to put a bigger tire on the front you might need to switch out forks from a larger bike to accomodate the larger wheel. If you look at Baird's bike, there's not much clearance on his front fork to put a larger wheel. If you got a 26" frame you could put a smaller tire on the back and maybe a 27" or 28" tire on the front if you wanted to. I've got a springer front end on my 26" frame. I could fit a 28" tire on that if I wanted to.