I have a 58 Schwinn Starlet, and all i'm missing to make it complete are truss rods. I have a set of Shwinn truss rods for a 26" bicycle (it is a 26) and they are way too long. So I got a set of 24" truss rods. Just too short (maybe a 1/2"). Does anyone know why? Where I can get this mysterious middle size? Thanks!