Drive the value of a Follow Path constraint I have a project where I would like to use a bones rotation value to move another bone along a brzier curve. 

I have a bezier curve with the bone that is constrained to the curve with a "follow path " constraint. 

I have the bone i want to use to drive the "offset" value of the follow path constraint. 

I run into a problem where the driver is affecting the bone to fast. It seems the conversion the driver is doing is muddled. 

I have a link to my file. 

Please help if possible!

https://drive.google.com/file/d/1OGM6t1OQX3MvETzCNrDbSz-EiSbqyI_W/view?usp=sharing

my objective is to rotate a bone  and have it drive another bone along the bezier curve. I wish for the main bone that is driving the bone on the path to complete a full 360 degress before the bone on the path finishes.
Right-click on the Offset value of your constraint.  Add driver ->
Scripted Expression (don't worry, no script needed) 
Open a Driver Window (Shift F6)

In the driver select the armature as the object, and the control
bone as the bone.
Choose Y location and local space.
The expression should just be var, nothing behind it.
Move the controller in local y direction (in your scene global z)