14
Adjusting The Timing Chain Tension
Periodically, the tension of the timing chain must be checked. The tension should be maintained
at 1/2” of total vertical deflection. Wear and stretch will cause the tension to change over
time.
1. Clean and lubricate the timing chain.
2.
MEASURE THE TENSION
- On the upper length of the chain in the middle of the front and
rear timing chainrings, move the chain up and down. You should be able to lift it up 1/4” and
move it down 1/4.” This is 1/2” vertical deflection.
Turn the crank to rotate the wheel so you can check the chain tension at different links of the
chain at the same midpoint. If the chain seems tighter in some places, it may be an indication
of chain damage or some other problem. Have the chain replaced or the damage repaired
before attempting any adjustment. If the chain is in good condition continue to step 3.
3.
ADJUST THE TENSION
- Insert a 4 mm Allen key into the eccentric fixing bolt and turn it
counter-clockwise to loosen the eccentric. After the first turn or so, the wedge bolt will feel
loose then it may seem to tighten as it pushes the wedge backward freeing up the eccentric
to rotate in the BB shell. When the wedge is loose and the eccentric assembly is free to rotate
within the bottom bracket shell , insert the end of an Allen key into one of the eccentric
holes and rotate it until the correct vertical chain deflection is reached. See next figure.
4.
RETIGHTEN THE FIXING BOLT
- When the chain tension is set, tighten the wedge bolt to the
specified torque.
WARNING
INCORRECT CHAIN TENSION ADJUSTMENT CAN CAUSE YOU TO HAVE AN ACCIDENT.
A chain that it too loose can come off and a chain that is too tight can bind, break or accelerate
wear on other parts . Both conditions can lead to an accident.
If you do not understand these instructions or are unable to complete them as described,
please have the performed by a professional bike mechanic.
