If checking suspension sag isn’t a regular part of your bike maintenance routine, you’re missing a key component of performance. Determining proper sag—on an air or coil shock—can be difficult for several reasons.
Air shocks: Most new forks and air shocks come with an O-ring on the stanchion or shock shaft that can aid in sag setup, but this simple tool can often be awkward to access and decreases the likelihood of an accurate setting. Plus, what do you do when your O-ring becomes damaged or breaks?
Coil shocks: Measuring sag on a coil shock requires the help of a friend, and relying on a friend’s mechanical ability isn’t always wise.
WHAT IS SAG?
Rider sag is the measurement of how much the fork and shock compress when you get on the bike. Setting the sag lets you change where in the range your suspension “sits” with you on board, and it gives the suspension an initial point to work from in either direction. Most mountain bike suspension systems require between 20- and 35-percent sag.