Have to pedal like crazy to reach max speeds.... wrong gearing?

[m@Robertson]

I believe what is being referred to as a tensioner is correctly installed. It appears exactly as mine does. You can also check out a clear photo of it from Propel Bikes at 9:28 in this video:

. Tension is adjusted with the two screws, one on each side and accessed through the circular opening of the bracket perpendicular to the frame. Of course the wheel has to be loosened to allow the tension screw to move the wheel fore and aft. I'm not sure, but the gizmo being referred to as the tensioner is more of a belt retainer.

That makes sense. My Gates belt'd bike used two tensioners very similar to this.

But for that gizmo to have as its purpose belt retention on the sprocket... thats kinda weird. although I guess if you have a poorly adjusted belt the way @philippe_kruse did, it may serve a purpose in keeping the belt from detaching. Gates belts should pretty much be almost bulletproof thanks to that center rib on the sprocket.

Certainly I have seen other R&M belted bikes use actual tensioners. I guess not this one.

 

[JRA]

Couldn't of said it better myself.

Hopefully the above mentioned will get you where you want to go.