tri-cycle

Design.An aphrodisiac.As my friends would say"whud a thunk it?" My tri/bike was a simple Murray that let me fly to the ends of the world......well,o.k.,the end of the block...same same.Now,at 56,I come across this x design(everything new is"X")A trike as you start,then,as you motate,the rear wheels close together forming a single rear wheel(ala..bike).My small pea brain looked in amazement.Where did the spokes go?Where were they in '55?I guess my only REAL question is,"How do you put cards in the spokeless wheels to make that magical sound?In time,all will be answered I know.Thanks for your ear.D.