Setting Sag

Forks

This is essentially the difference between your suspension being fully extended and then naturally compressed with you sitting on the bike. You need 3 people to do this right, and you also need to be in full gear (but not including helmet) whether that be weather suit or race leathers, boots, gloves, back protector etc. Make sure that you have paper and pen on hand before you start!

In order to set the SAG properly, the motorcycle cannot be on any front or rear stand as it must have both wheels on the ground. To set the correct SAG on the forks, 2 people must hold a handlebar each and lift the front end in order to extend the forks to their maximum length (figure 1). The person measuring (metric tape measure is easier) must pick a point to measure from (traditional forks should be measured from the base of the triple clamp to the shoulder of the lower fork leg leg, and upside down forks should be measured from the shoulder of the upper leg to the end of the chrome tube where it enters the axle casting-figure 2).

ONCE YOU HAVE PICKED THE POINTS TO MEASURE FROM, DO NOT CHANGE !

Once the measurement for the forks at full extension has been recorded, the rider is then required to sit on the bike. The rider climbs aboard with feet on the ground until the person holding the bike upright at the rear (using whatever is solid on the rear of the motorcycle) has a firm grip. The person holding the bike then instructs the rider to put his feet on the pegs and pull on the front brake lever to keep the bike stationary. The person doing the measuring compresses the front suspension by pulling down on the handlebars and then lets the bike settle. The second measurement is taken using the same two points used previously, and that number is recorded (figure 3). Simple math of the larger minus the smaller number will provide you with the SAG number.

As a general principle, the front fork SAG should be approximately 32 to 38mm. If there is more than 38mm, preload (if available, see figure 4) can be added. Turns clockwise add preload. If all the available preload is added and the resulting number is still greater than 38mm, then the fork springs are too soft and need to be replaced.

Shocks

To set the correct SAG on the shock, 1 person must grab the sub frame and lift the rear end in order to extend the shock to its maximum length. The person measuring (metric tape measure is easier) must pick a point to measure from the center of the rear axle to a point on the plastic (using contour lines, edges of decals etc helps). This measurement must be as straight a vertical line as possible!

ONCE YOU HAVE PICKED THE POINTS TO MEASURE FROM, DO NOT CHANGE!

Once the measurement for the shock at full extension has been recorded, the rider is required to sit on the bike. The rider climbs aboard with feet on the ground until the person holding the bike at the front (using the upper triple clamp is easiest) has a firm grip. The person holding the bike then instructs the rider to put his feet on the pegs and pull on the front brake lever to keep the bike stationary. The person doing the measuring compresses the rear suspension by pushing down on the rear of the bike and then lets the bike settle. The second measurement is taken using the same two points used previously, and that number is recorded (figure 7). Simple math of the larger minus the smaller number will provide you with the SAG number.

As a general principle, the rear SAG should be approximately 28 to 32mm. If there is more than 32mm, preload (if available) can be added using the appropriate tool(s). Those shocks with ramp adjusters (eg: Yamaha R6 OEM shock) have limited preload, whereas some with lock rings (Penske, Fox, Ohlins, WP) have a great deal more adjustment. If you add more than 5 turns of preload on a rear spring the spring will become harsh, so that is a good indication that you have the wrong spring on the bike.

Note: Also note that some springs are straight rate (have the same rate throughout their range of movement), whereas others are progressive rates (where the rate increases during the shock travel). It is better to have a straight rate spring if you are considering racing.

• Showa
  GSXR (600 & 750)
  Honda (All)
• KYB
  GSXR 1000
  Yamaha R6
  Yamaha 98-02 R1

*You will need a special removal tool for the GSXR 1000. See our tools page.