"The Melvin Chain Tensioner is the part that makes a single-speed conversion viable on frames that were never designed for it. The machined aluminum pulleys give a clear visual cue when tension is right, so setup is repeatable rather than a matter of feel, and the side-to-side float means minor chainline imperfections do not translate into drivetrain noise or wear. What Our Gearhead® Experts Are Saying:""The pivot spacers let me dial the chainline without swapping the whole setup. That's the detail that makes this work on frames where the dropout geometry leaves no room for error."""