life:

May is National Bike Month in the United States, and in towns and cities all over the country people young and old are clambering aboard their beloved machines and blithely pedaling into a brighter, cleaner, healthier tomorrow. Or losing their balance, wiping out and maiming themselves. Either way, they’re getting exercise. Happy cycling, everybody!

Here, LIFE.com offers a selection of photos of these preposterous creations from six long decades ago — mechanistic marvels that belie the famous old saying (which we just made up) that there’s no such thing as a useless bicycle…