Chain Tensioner Pimp my spring-loaded chain tensioner...

Discussion in 'Transmission / Drivetrain' started by Max-M, Apr 17, 2012.

  1. Max-M

    Max-M Member

    I've been wanting to put a spring-loaded chain tensioner on my cruiser, and I figured that I'd design and fabricate one myself. But I found one on the LiveFast Motors site (great people-customer service-shipping speed). Kudos to LiveFast motors:

    So, I bought one of these tensioners from LiveFast for $35 (with free shipping), and I had it in three days: Arizona to Connecticut.

    As seen in the "after" photo below, I swapped the stock tensioner's nylon roller for a 17-tooth, idler sprocket with a bearing ($20 at Tractor Supply). This required drilling a 9/16" hole in the tensioner arm to accomodate the 1/2" bolt that holds the 1/2" bore sprocket/bearing onto the tensioner arm. The idler sprocket is sized for my hefty #41 chain.

    Then, I replaced the tensioner's stock fasteners with black, Allen head ones.

    Additionally, and most obviously, I "blacked out" the three main parts of the tensioner: I used a tough, thin plastic sheet material that I cut from the cover of a 3-ring binder. I applied an aerosol spray rubber cement (3M Super 77 Multipuropose Adhesive) to each mating surface (metal + sheet plastic), and let each piece "tack up." Then I mated each piece, rubbed them down for adhesion, and then carefully trimmed off the excess sheet plastic from all edges and holes. This is a "finish" that I find is much more durable and better-looking than a spray-painted "black-out." Once the glued-and-tacky plastic surface meets the glued-and-tacky metal surface, they are NOT coming apart or scratching! Ever!

    All of this "black-out" activity is an effort to make the tensioner less visually obvious. It DOES have kind of an "Erector Set" look to it in its stock form, and I think that my treatment makes it look more like an exotic mechanical component! I do the same thing with my 56-tooth rear drive sprockets; they look like big' ol shiny pie tins otherwise!

    Mechanically, the tensioner works great. And for various reasons, I prefer having the tensioner attached to a seat-stay (as is the typical use of this tensioner) instead of in the usual chain-stay mounting position of most motorized bike chain tensioners.

    If anybody has any questions about this project, please don't hesitate to ask.


    Attached Files:

    Last edited: Apr 17, 2012

  2. tom1850

    tom1850 Member

    Nice. Great idea and implementation.
  3. Cavi Mike

    Cavi Mike Member

    I assume you mean you have it mounted on the top half of the chain, meaning the engine can fight it, push it out of the way, cause slack on the bottom half and then cause the chain to derail?

    There's a reason why tensioners always go on the slack side of a chain or belt. Only idlers should be used on the tensioned side.
  4. Max-M

    Max-M Member

    Mike: You've negatively jumped to the wrong conclusion. The tensioner is mounted to my bike's left-side seat stay, and the idler sprocket engages the underside of the bottom run of chain. The spring-loaded tensioner pushes upward on the chain.

    (Bicycle Dictionary: The seat stays connect the top of the seat tube [often at or near the same point as the top tube] to the rear fork dropouts.)
  5. Cavi Mike

    Cavi Mike Member