Originally Posted by
wrk101
Because the spacing will be wrong. Those old 5 speed Schwinn hubs are not spaced for 6/7 speed freewheels. You could always squeeze in a wider rear wheel, but that means additional $$.
he could go use a Ultra-6 freewheel if he can find them. These use 7s spacing to pack 6 sprockets onto a freewheel the width of a 5s. they were a popular upgrade for 120mm hubs back in the early days of 7 speed. But he cannot go to a standard 6s or 7s without 126mm OLD minimum.