In this thread, I detect confusion over two radically different (both correct!) uses of the term, "tubular." Yes, tubular (sew-up) road racing tyres are glued onto special flangeless rims, and the latter are almost always aluminum, with a boxlike cross-section. However, I believe Schwinn referred to some of its heavy flanged steel clincher rims as "tubular," because their double-walled construction resulted from flattening a length of steel tubing before forming it into the final product. If you look at an old steel Schwinn rim, you will see a seam running along the spoke holes around the outside edge, under the rim strip, but not on the visible inside surface.