When I was studying in NYC I would grab abandoned baby strollers and convert the wheels into bass wheels. This often worked pretty well. I would sometimes only need to fit a 3/8" piece of aluminum rod into the housing, which was ready-made for this diameter, and the result was a double-wheel with a built in rubber shock-absorber. I sold a bunch of them to my fellow students at Mannes. I see no advantage to "screwing on" a wheel assembly instead of simply removing your pin and sticking in the shaft of your wheel. Seems less efficient on the whole, in fact. I haven't tried the "Buggy" and haven't needed to "stroll" long distances in recent years, but the "Buggy" does seem like a good option. That said, though, I think I'd prefer one of those big inflated airplane wheels when going over Soho cobblestones to solid skateboard wheels.