Gear head
 

I hijacked this off FB . I have no idea .
https://www.facebook.com/photo.php?f...&theater&ifg=1

I'm inclined to think it's a photoshop job. Think about where the chain-line would be if there was a chain. Those gears shouldn't mesh face to face the way they do. Besides, where's the left crank-arm?

Or is there an optical illusion?

see it but with multiple gears.:eek:

Scroll down on this page, second or third image:
» Chainless Bicycle Adverts & Pictures Chainless Bicycles ? Shaft-Drive, Acatene, Cardan
I think it's a real bike, at least the idea is somewhat feasible.
Getting any kind of little pebble or stone in there would just lock the thing up, it lacks the flexibility of a chain system.
The rear axle would need to be very firmly set in a definite location, unlike chain-drive bikes which can operate with more or less chain distance.
I would think lubrication would be a bigger issue than with chains. Or more to the point, you'd be replacing gears periodically rather than chains.
Walking or riding over a curb would bang the gears up.

I had something like it on my SAT test in the mid 60's..