I'm learning along with you, because I bought a Claud Butler yesterday on Craig's List, and I was surprised to find that the rims were 27" Super Champion Gentleman. More-surprising-yet was that the rear rim is schraeder. Velobase says they built them both ways. The tube inside the rear tire is a CST from China, and seems very substantial. Not sure I want to ride with such a heavy tube if I have a tire with puncture protection.