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!

Dwarf bike built by a former vaudevillian named Harry Sykes, who once built a bike half this size.But back in 1948, a number of inspired amateur craftsmen — not content with riding mundane, conventional bicycles — took their enthusiasm to another, unlikely level and … well, let’s let LIFE tell it, in the words the magazine used in its December 27, 1948, issue:

“To Webster a bicycle is ‘a light vehicle having two wheels, one behind the other.’ Such a definition theoretically describes the contraptions [seen in the article], but fails to do justice to the imagination of the Chicago chapter of the National Bicycle Dealers’ Association.

“By artfully applying welders’ torches to metal tubing, the chapter’s members transform ordinary, utilitarian bicycles into traveling monstrosities. By far the most outlandish ideas have come from the Steinlauf family, who produced from their bicycle repair shop most of the oddities [shown in the article]. They are hazardous; generally at least one member of the clan is to be found in the hospital.”

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.

Read more: http://life.time.com/curiosities/hell-on-wheels-in-praise-of-mutant-bicycles/#ixzz1zlwcNDfa

> LIFE (15 pictures)