I just bought new wheels for an older Schwinn frame. I don't know the date it was made, but it's a steel frame and as built it had stem shifters and a cup-and-cone bottom bracket, etc. Probably from some time in the 80s, I estimate.
The spacing between the rear dropouts on the frame itself is 130mm; the new rear wheel and hub arrived spaced to 120mm. It's a flip flop hub with a solid axle (no quick release). I am able to get the hub to fit snugly between the dropouts just by tightening the axle nuts, since the steel frame will bend to make up that 5mm on each side pretty easily.
Is this a safe setup? Or do I need to add spacers to the hub to fit the 130mm frame without any bending?