Which side of the chain experiences sag when properly tensioned with the taut side remaining tight?

• A. slack side
• B. taut side
• C. center side
• D. bottom side

Answer: (A)

When a chain is properly tensioned, one section is kept tight by the driving sprocket—the taut side—while the opposite section has less tension and will sag under gravity. That sagging section is the slack side. The slack side needs some play to accommodate chain growth, thermal expansion, and shock loads, while the taut side stays tight to keep the chain engaged and prevent skipping. Terms like center side or bottom side aren’t standard explanations here, and they don’t describe the actual behavior as clearly as the idea of a slack side that sags.