@fishin&routin,
not sure why you have two(are they identical?). One may be for the parallel guide. The one you show, is for routing the edge of a board. In practice, the little bearing wheel should cover almost all of the bit, viewed end-on as you show it. Only the cutting edge of the carbide flutes should be exposed, and then not completely.
The bearing wheel needs to ride on the edge of the board (meaning you cannot use that guide if you want to machine the whole thickness of the edge). If more of the bit were exposed, it would be difficult to keep the router aligned at 90 degrees to the edge, leaving an uneven edge. Ditto if the bit diameter exceeds the bearing wheel diameter.
The guide allows you to follow a curve (convex or concave). For a straight edge. You might find a parallel guide easier to use.
not sure why you have two(are they identical?). One may be for the parallel guide. The one you show, is for routing the edge of a board. In practice, the little bearing wheel should cover almost all of the bit, viewed end-on as you show it. Only the cutting edge of the carbide flutes should be exposed, and then not completely.
The bearing wheel needs to ride on the edge of the board (meaning you cannot use that guide if you want to machine the whole thickness of the edge). If more of the bit were exposed, it would be difficult to keep the router aligned at 90 degrees to the edge, leaving an uneven edge. Ditto if the bit diameter exceeds the bearing wheel diameter.
The guide allows you to follow a curve (convex or concave). For a straight edge. You might find a parallel guide easier to use.