Bike Chain Tensioner

This chain tensioner can be used to address issues with chain hopping, chain slap, and rattles. It can be printed and assembled for less than $6, and offers equivalent perfomance to comercial products sold for $30.

Bill of Materials

1. Tensioner.scad
2. (2) ZipTies
3. (1) 8-32 Thread, 1-1/4" Length Machine Screw (eg. McMasterCarr:91792A201)
4. (1) 8-32 Thread Locknut (eg. McMasterCarr:91831a009)

Tools needed

1. MOST Delta RepRap or similar RepRap 3-D printer
2. Screwdriver
3. Adjustable Wrench or Pliers

Skills and knowledge needed

• Ability to use a 3d printer.
• Ability to use a wrench and screwdriver.

Technical Specifications and Assembly Instructions

All parts are symetric such that component orientation is not an issue.

Assembly:

1. Ziptie the cage to the Bicycle frame just above chain.
2. Hold the chain up so it is captured in the cage.
3. Bolt the pully in place
4. gently crank the pedals by hand and shift throug all gears to ensure nothing is binding

Common Problems and Solutions

• If the fit to they bicycle is loose or overly tight the OpenScad variable "pipeDia" can be set to match your bike frame's tubing diameter.

Cost savings

• Approximatly $23.50 (78.3%)
  • 30g of PLA at approx. $30/kg = $0.90
  • Machine Screw, Locknut, and bag of zip ties approx $5.60 at local hardware store
  • Equivalent Chain Tesnsioner: Bionicon C.GUIDE approx. $30
  • 30 - (5.60 + 0.90) = $23.50