700x23 does fit on 26"
MTB frames designed with FAT tires in mind, but V-brakes would need an adaptor to work right, and the frame would have to fit 26x2.2in tires at least.
Just to be sure, you have a
MTB, right? or do you actually have a 26x
1-1/4 (S-6, 597mm). Decimals and fraction sizes are not the same and it's easy to confuse the two.
said adaptor:
http://www.mavic.com/mtb/products/ca....323944.3.aspx
read this:
http://www.sheldonbrown.com/tire-sizing.html