I work in a wire manufacturing plant and wondered if the "Cable Harness" feature of Inventor 2012 is adaptable enough to define the wire diameter (Typically 1-2 mm) and select the root groove of pulleys / sheaves as the wire's path.
My first attempt ended up with a wire touching a single tangent point around my guide pulley and the wire having a "natural" bend such that it bowed out of the real life path. My wire is under tension in our process, so the path should be straight as the wire traverses around sheaves / rollers to reach its destination point.
The cable and harness is limited when it comes to creating a wire under tension. I don't think you'll be able to get the wire as straight as you like it. I'd suggest creating an adaptive 3D sketch to create the sweep path for a wire. Work Features added to a sheaves/rollers could be used to help create the path and make it scaleable.
I would add at least 3 points to the wire run at each pulley and then "redefine" (with offset set at the wire radius) those points to go around the pulley (at the 3 quadrants where the wire will touch) That "should" come fairly close to what you want.
But a sweep might be a better option if that doesn't work.