Eccentric / Timing Chain Adjustment

As the cross over chains stretch, you will need to adjust the eccentrics to tension the chain.

We switched from set screw type eccentrics to internal expanding eccentrics in 2004. Specific instructions for the set screw type will be listed below.

Using a 4mm hex key wrench, loosen the eccentric. There is an access hole on the right side of the eccentric. You will feel the bolt get loose as you back it out, after a few turns, it will feel like it is getting tight again, keep turning until the eccentric can be rotated.
Rotate the eccentric to tighten or loosen the timing chain. The timing chain should be loose enough to prevent binding and tight enough to keep from falling off.

The chain should move about 1/2″ for the front and 1/4″ for the rear without using force.

When you think the chain is adjusted, tighten the eccentric and rotate the cranks to see if there is a tight spot.

If the chain is tight in one spot, readjust the eccentric and check again.

If you are confused, this would be a good time to visit your bike shop and watch them do it.

CAUTION: Take care to not catch your fingers between the chain and chainring. It can cut your finger off.


Pre 2005 Set Screw Type Eccentric (Older model)

Loosen the set screws under the bottom bracket shell. There are two of them, and 1 full turn should be plenty.

The eccentric should be rotated so the spindle is above the bottom bracket shell centerline. (see drawing below) This is important because the set screws can damage the bearings if the bearings are right above the set screws.

You can use either a pin spanner wrench or a 36mm headset wrench to rotate the eccentric.

Adjust chain as described above.

When you think the eccentric is adjusted, snug up the set screws (do not tighten yet) and rotate the cranks to see if there is a tight spot. Readjust if necessary. Tighten set screw to 60 to 70 in-lbs (7 to 8 nm)