Kufman
Member
The challenge with this simple type of tandem are two-fold (as per Sheldon Brown): stiffness - twisting because they are only held together by the rear/front axle! (scary) AND they have to be able to pivot on that same axle for road grade transitions (speed bump would first lift the middle wheel, then one end then the middle wheel again and the reverse going over a pothole or dip. But the huge advantage is (bird language) cheap, cheap, cheap and easily available parts.
PS what are those blue tires, they look sharp!
The blue tires are from Kenda. I don't think they are made anymore.