DETERMINING THE PROPER REAR SHOCK SPRING RATE

 Suspension Tips

Too Tech Tip #2:  Check your static sag to determine if you have the proper rear spring rate.

Want to start tuning your rear suspension for improved handling?

Having the proper spring rate in the rear is an important first step!

Having the proper spring rates in the front and rear is critical for proper handling.  The spring rates must be selected to match the size of the bike and weight of the rider.  Heavier riders require stiffer spring rates.  A good approximation of your rear spring requirements can be found by measuring the rear suspension’s static sag.   This universally accepted measurement will quickly determine if your rear spring is approximately correct for your weight.  Static Sag is a measurement of how much the bike sags under it’s own weight.

  ·      YOU MUST FIRST SET THE RACE SAG!

(See “How To Set Race Sag “ on this web site)

·      The First measurement is taken with the bike on a center

     stand with the rear wheel hanging freely in the air. 

     Measure the distance between the rear axle and some

     convenient point near the fender like a seat bolt.

·         The Second measurement is taken with the bike on

      the ground.  Push up and down to allow the bike to

      find it’s natural resting position. Again, measure the

     distance between the same two points used above.

·         The Static Sag is the difference between the First and Second measurement.

                   FIRST               24”

                --    SECOND     -- 23”        

                =    STATIC SAG     1”

    3/4" to 1 1/4  inches indicates the rear spring is correct.

• If the static sag is less than 1/2 inch – the spring is too definitely soft.

• If the static sag is greater than 1 3/4 inch – the spring is too definitely stiff.

• Ideally the static sag will be between 3/4 and 1 1/2 inches.

Note: There is much confusion about the specifications above!  Think of it this way.  Before checking your static sag, you must first set your race sag to 4 inches.  If you have a rear spring that is too soft, you will have to really crank down on the preload to get the 4 inches of race sag.  You will be able to get 4 inches at some point, but you may have cranked in so much preload that without you on the bike, the additional spring preload will hold the bike up real high, maybe even topped out.  If you are close to topped out, the static sag number will be small - under 1/2".

        Rick Johnson

        Too Tech Racing

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