Origin of the word “crank”?

Question by Savage: Origin of the word “crank”?
When “crank” refers to a drug, where did the term come from? Theories welcome.
The reason I ask is that I saw a documentary that said the spread of meth began with biker gangs who used to smuggle the drug in their crankcases, hence the name “crank”. This sounds a little far-fetched. Has anyone else heard this explanation?

Best answer:

Answer by Silverramette
“Crank” (or kook, crackpot, or quack) is a pejorative term for a person who writes or speaks in an authoritative fashion about a particular subject, often in science, but is alleged to have false or even ludicrous beliefs. Usage of the label is often subjective, with proponents of competing theories labeling their opponents cranks, but typically is used to describe someone who is well out of mainstream opinion on a matter. In most cases the people labeled as crackpots turn out to be wrong.

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