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Setting Sag

Discussion in 'Mechanical & Technical' started by LRG, Oct 13, 2004.

  1. Everyone is always concerned about hp. But anyone that rides a lot of twisties or track days will most likely say suspension is where its at. Unfortunately this is where manufacturers save cash, the stock shock on my 1k was junk and sprung to soft for my lard ass. All that being said the first thing a sport rider should do after getting a new ride is set the sag. This will give you a place to start.

    Depending on your expertise of part of the world SAG can be referred to by different terms. For our purpose we are using SAG to mean the adjustment with Rider or Rider Sag.

    Tools Needed
    Paper
    Pen
    Tape Measure- A Metric tape is easier
    2 Willing Riding Buddies-This is the Tool Part hopefully one can read a tape.


    FORKS:

    This is essentially the difference between your suspension being fully extended and then naturally compressed with you sitting on the bike. Grab 2 buddies and get your gear on (what you normally wear riding).

    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. Two people must hold a handlebar each and lift the front end in order to extend the forks to their maximum length. The person measuring must pick a point to measure from. The easiest place to measure on a newer sportbikes is from the bottom of the forks dust seal to where the fork tube enters the axle casing. Write down the measurement. Duh

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

    After getting the measurement at full extension. Get your gear on and hop on your bike. While one person holds the bike solidly, put your feet on your pegs and get in a reasonable tuck/ agressive riding positon.
    Have the person measuring compress the forks a bit by pulling down on the bars. then let them settle. Now take the measurment. Now subtract 2nd measurement from the first. This is your front sag.

    Forks Fully Extended- Forks with Rider = SAG

    Rule of thumb FRONT SAG should be 32-38mm~( 1.25"-1.50")

    If there is more than 38mm, preload 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. Likewise if not enough Sag is found preload, thus sag can be dialed out. If you still don't get 32 mm of SAG springs are too stiff.



    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 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.


    Shock Fully Extended- Shock with Rider = SAG

    Rule of thumb REAR SAG should be 28-32mm~( 1.125"-1.25")

    Again too much Sag add preload, not enough remove preload.
    Most shocks today have a lock ring and you will need a spanner or a screwdriver and a hammer-Although for those that are anal this will put indentations in the lock ring. 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.

    If you have questions about how to adjust the preload for your bike's forks or shock consult your shop manual for your bike. I know everyone has one cause only a dummy doesn't buy a shop manual when you get a bike. More to come.
     
  2. good post LRG. Usefull info for all who like to actually turn there bikes.
     

  3. Just had mine done over the weekend. The only bad part was I got a nail in my rear tire(what a bummer).Most people I have talked to never set the sag or anything else on there bikes, its to bad that they will never understand how much of a differance it makes....
     
  4. jabstar17

    jabstar17 Le Bitch

    I am one of those who has never touched my suspension. But! I do understand the difference, I set my old bike up a couple of years ago. I have put 12,000 miles on this one, and just haven't had the chance to set it up.
     
  5. jezterr

    jezterr Retired Admin

    i actually set my sag as recommended by sport rider... the bike got like 20 times better.