Setting Sag on your SUSPENSION

1 Measure Fork Sag

       The most common problem with forks is incorrect sag.  Sag is how far your fork compresses when you sit on your bike on a flat surface.  Correct sag allows your front wheel to follow the contour of the ground as you ride.  Measuring sag also shows whether your fork has the right kind of springs.  Place a zip-tie on the upper stanchion at the seal.  Sit on the bike in a comfortable riding position, with your elbow against a wall, then lean over to let your weight compress the fork, like you’re in a normal riding position.  Get off and measure in milimetres the space between the seal and the zip-tie;  that’s your sag

2 Adjust Sag

       How much sag you want depends on how you ride, and your fork’s travel.  Heavier or more aggressive riders usually run sat at the low end to avoid bottoming out the fork.  Some lightweight cross country riders, or cylists who want ultra plush rides, run sag towards the high end; this makes the fork more active on small bumps and more responsive to light riders (who otherwise might never use all of the fork’s travel).  You adjust sag by changing springs or, for air forks, adding or removing air pressure with a fork pump.  For coil forks, you have to buy stiffer or softer springs. (The best time to check sag is when you buy a new bike or fork because the shop can help you swap in the correct spring for your weight and riding style.) You can also alter sag by adjusting the pre-load on your fork.

3 Dial in rear Sag

       Use the same technique as measuring fork sag.  But don’t use your bike’s total travel to determine sag.  A 5-inch travel bike doesn’t have a shock that travels 5 inches.  There’s usually about a 2.5:1 ratio of wheel-to-shock movement.  You either need to know this ratio or specific travel your shock has (usually 40-60mm).   Change rear sag by swapping springs, adding air or adjusting pre-load.  I’ve seen a lot of people ignore their rear suspension and so blaming an uncomfortable ride on the bike model / make.  Adjusting and measuring rear sag lets you balance the front and rear suspension so the bike doesn’t ride like a rocking horse.