Yesterday I put a Gazz 3X26 on a sun doublewide rim onto a Yuni 26” frame. It fits! Well almost there was zero clearance so I took the bearing shims that came with the KH cranks that I recently purchased, now there is about 2mm clearance on the top and maybe 5mm on sides. MauMau took it on our afternoon ride down a steep slippery slopply muddy trail and it did fine. It measures just a little under 28” and looks like a front motorcycle tire. If I put together another one of these I would go with the Yuni 28” frame to get a little more top clearance.
Happy riding