3 Things to Know About Setting Chain Tension

Aim for half an inch of play Set the chain so you have about 12-15mm of vertical movement at the midpoint of the bottom run. That is roughly half an inch.

Overtightening causes damage Too much tension puts heat into the bearings and chain, and can snap a derailleur or bend a hanger. Most people overtighten because it feels more secure, but it is not.

Check tension at the tautest spot Test with the cranks in the position where the chain is tightest, usually when the crank arm points forward. If it is tight there, it will be too tight elsewhere. A slightly loose chain is safer than a perfectly tight one.