26"

 Ended up making more clearance for the cranks and a bigger sprocket with a yoke. This was the first of its kind, having a bend down the center. The objective was to make the thing as laterally stiff as possible. This frame has good clearance for a huge round profile tire and a 32t sprocket (even at 14.5" CS)

Little short stack 98mm head tube for a tapered steerer and an 83mm Spanish BB. 

The 135mm rear end is the best way to get clearance for tires and a sprocket on one of these street 26"s. They have at least 7mm more wiggle room than the 110mm rear ends. The optimal design for pegs would be a 14X135mm but those hubs don't appear to exist anymore.