Chain sag is measured by rotating the sprockets so there is little or no chain sag in the __________ side and measuring the sag in the __________ side.

• A. taut, slack
• B. slack, taut
• C. center, edge
• D. top, bottom

Answer: (A)

Measuring chain sag hinges on isolating the loose, low-tension side from the tight, high-tension side. By rotating the sprockets so there is little or no sag on the taut side, you set a stable baseline with the chain pulled tight. Then you measure the sag on the slack side—the side with lower tension. The amount of drop on this side shows how much the chain sags under its own weight and normal loading, which is the useful reading for adjustment or wear assessment. This approach works because keeping one side taut removes variation from changing tension, letting the slack side reveal true sag. The other options don’t describe a tension-based measurement, so they wouldn’t correctly identify where to measure sag.