Here, the horizontal bone is parent of the Pin bone and the Pin bone is the target of the vertical bone.
So, I created a cycle for the Pin bone to go left/right/left.
Now, since the Pin bone is child of the horizontal bone, if I scale the horizontal bone, the space the pin bone travels is also being scaled, so by scaling the bone, I could dilate and contract the movement of the pin bone.
Then I added an extra Smart bone to control the scale. It's not necessary to add it, but it allows to animate more easily:

Then I was thinking how this technique could have real world use, so I tried with some dynamic bones and, more important, I added an extra vertical bone to control the height of the cycle.
So now the cycle could be in two dimensions, with the horizontal bone scaling X and the vertical bone scaling Y.

By having the option to scale both axis, now we can add any animation cycle easly scaled.
I'm thinking this could be specially useful to have crowds with slighly different walkcycles, for instance.

And by adding an extra Smart bone containing the base walk cycle, you could animate the intensity of the movement, but also the speed of the walk.

I hope all this makes sense!
You can download the Moho files here
https://www.dropbox.com/s/3bddil1u4kvj7 ... .zip?raw=1