I'd say pre 70 for Vintage. What we're talking about here are bicycles suitable for becoming motorbicycles. Pre 70 you still have many bikes still made in the USA and middleweights were still around. Many of those, including the Schwinns had 1.175 tires, but still had solid and relatively heavy frames. In my opinion a lightweight bike with skinny tires is not a good candidate for an in frame engine... a little friction drive maybe, but not a 'serious' motorbicycle . (I know, I'm showing my biases and others would not agree.) While I think balloon tire bikes made in the USA are the best candidates for an in frame engine, some of the early sixties bikes were strong and pretty cool looking. After that we're not talking classic, "vintage" bikes anymore. Single speed with a coaster brake is another feature of these old bikes, with a few exceptions, like the 2 speed Bendix hub found on high end Schwinns as an option. I must be stuck in some kind of time warp since these are the only bikes which interest me. A pain to pedal, but great to ride with a motor. There was a time early on when motorcycles and bicycles were much the same critter. The engine made them markedly different, but the bikes themselves had a common origin. As time went by motorcycles became more powerful, the frames got heavier, suspension became more sophisticated and the difference with bicycles became more pronounced. The bikes were still pretty much the same until after WWII when heavyweights gave way to middleweights and finally lightweights with multiple gears and now mountain bikes. Some of the newer bikes are almost as different from the old timers as the motorcycles are. The bikes we're building are much like those of the early days when the evolutionary split between strictly pedaled and motored first occurred. The motors are underpowered and primitive and especially the old bikes are heavy riders... a perfect match in my opinion. That's how I see it, anyway.
SB
