The Chainlink

Anyone interested in puzzles? Do you have any bike puzzles to share?

Here is one I saw in a book*. You can actually try this if you have a fixed gear at your disposal.

Below is a regular fixed gear bike. As you can see(!?), a lose yellow rope is resting on the floor where one end is tied to the left pedal spindle.

If someone was to kneel in front of the bike and pull the rope, will the crank move clockwise, counter clockwise, or not at all ?

You can assume a magic force is keeping the bike upright and front tire pointing straight. Oh, and assume the wheels do have spokes although it looks otherwise.

* Mathematical Carnival by M. Gardner

original bike photo from:

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Is there a solution posted?

How long is the crank, how many teeth are on the chainwheel and cog?  i.e. what is the gain ratio?

Those details could change things for the first few inches the rope is pulled -but once the crank gets closer to 90-degrees of rotation that will be a moot point...

This is exactly what I had in mind to post here :)

Melanie K said:



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