Anti-Chain-Suck (ACS) Bracket Adjustment

If you have experienced chain-suck, (the chain gets stuck in the drive gears by wrapping around the chainring too far), your ACS bracket is adjusted too far from the chainrings, or the ACS bracket is bent, or both.

The bracket should be within .030” (.75mm) of the side of the chainrings. .030″ is the thickness of the edge of a credit card. Loosen the two 6mm Allen bolts on the back of the Intermediate Shaft about ½ turn. Slide the bracket toward the chainrings as close as you can without it rubbing the chainrings. As you tighten the bolts, be careful the bracket does not move. Tighten to about 60 to 70 in/lbs. (6.8 – 7.9 NM). Turn the cranks and make sure the bracket does not rub the chainrings.

If you bracket is bent, you should replace it. It is better to not have an ACS bracket than have one that is very bent or miss-adjusted. The bracket will make it harder to dislodge a chain-suck.