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WHY DO I SET SAG ON MY MOTORCYCLE?

Updated: May 7

SETTING SAG IS A CRAP SHOOT!


Well then how do I set sag on my motorcycle?

I set up my bike to “exactly” the sag my manual says, so my bike is dialed!... NOT!


To be honest if you just picked up a bike and are going to the track, you should set your sag, as you never know how far off it may be, and you do not know your spring rates.

But, after the proper springs are installed with proper preload by an experienced individual, then the true dial can happen.


At that point there is no need to set the exact sag and here's why.


Items that make your specific sag settings a crap shoot:


  • Exactly where were you sitting on the bike? Move back an inch, oops sag changed.


  • You’re tall so you sit back further. Did you have to hunker down to get the right sag?


  • You changed fork spring preload adjustment. Now that your front height is different than it was a minute ago does the rear sag number change because the bike is no longer at the same attitude?  Dang it!

  • How about those with top out springs. They keep the suspension from fully extending. Oops.


  • Changing fork springs changes fork height.


  • Changing fork height in the triple clamps. What line on my forks is exactly right for my 110mm of sag?


  • Riding whoops to San Felipe? You need more sag. So what number is correct then?


  • What valving do you have. A shim stack shuffle that most tuners rely on will change how high your fork rides in the stroke. How much high speed/low speed clickers are dialed in. It all changes ride height.


  • How do you know the manual’s sag number is right for you as you ride aggressive and forward on the bike and your buddy is so out of shape he can’t stand up anymore?


  • I just bought an oversized gas tank.


  • How about Kookie the desert racing dogs set up! Going to need more spring and preload.

Suspension101 How do I set my sag Kookie


So, generally the last thing we might check is sag, after testing, and just for documentation.

Working with a well informed pro rider he will take a 1 minute ride and give us direction for sag up or down. Another quick ride and a fine tune. 15 minutes and done.


The springs will be correct if done by a pro, so just get the right bike attitude and run.

Getting a repeatable sag can be good info for future adjustment when you ride in specific terrain.

An amateur racer that takes these notes has an advantage.

So, for repeatability, here is how you set your sag.


  1. Full gear on

  2. Stand straight with balls of your feet on the pegs

  3. Hands by riders sides

  4. Look straight ahead

If you set your sag exactly as stated above it will be accurate and it will be repeatable.


SETTING UP YOUR BIKE IS "NOT" DONE BY A SAG NUMBER

THINK ONLY STEERING PERFORMANCE


Lets look at some examples:

If you are riding a chopper and the forks are raked out and you’re not holding a line on road or trail many will have the death squeeze on the hand grips.

Even if your skull bandana is stylishly flapping in the wind and you look amazing.    All is not good!

It indicates your front end is higher than the rear for incorrect steering performance.

This is a very energy consuming set up.

Stable in straight line at speed but turning hurts because of the lack of control. Want to wear yourself out in a hurry? Throw some bags on your brand new adventure bike with no adjustments and go do a BDR. With the rear low and front high you will be worn out in no time.


Ok so you jump on your other bike, and this bike is set up completely different and you are riding a stink bug.

The bars turn quite easily and it feels nimble, but as you turn in, the bike lacks traction. Then when ridden at a higher speed you’re getting head shake and the front end feels loose.

This indicates the rear is higher than the front, and again is affecting steering performance.


IT COMES DOWN TO THE DIRTY WORDS, HOMEWORK AND TESTING.


Want a better performing, neutral steering, traction searching, stable front end? You mimmic the pros.


Example:

Going to San Felipe? You dial in your bike for whoops.

When done the bike is stable and front end is tapping the tops of the whoops as you win the 250.

Only for repeatability you then check your sag, so the next time you go to a whoop infested beat down you can set your bike up to the specs you already tested and know.

Don’t get me started on fork sag and static sag please!


ADVENTURE BIKES


We do a lot of adventure bikes so the above can be more extreme in some cases.

Many come with 15mm some even 18mm of fork spring preload. Ouch!

That is a brutal amount if you want any compliance in small chop, washboard etc. We many times keep a similar spring rate but we make shorter springs so the preload will be from 6mm to 10mm. It allows the front to sink into the forks further and stay light and fluffy when accelerating through small chop.

Many manufacturers also have 10 to 17mm of shock spring preload so we will reduce this as well. The rear sinks into the shock a bit more when you sit on the bike, but the bike is so much more comfortable and does not get upset or deflect as it did with 17mm of preload.


We often get the call or email.

I can’t get my sag number correct!

"This bike is supposed to have 73.33mm of rear sag EXACTLY and my fork sag is closer to 28.5% and 36.8% depending on which time I check.

"I have not ridden the bike yet because I simply do not know what to make of this."

"You installed the wrong springs."


Please, first ride the bike loaded as you would ride most of the time. See how she feels.

If you need more precise steering do not go immediately after shock preload, simply raise the forks in the triple clamps up to the next line or a bit past the last line. GET THE BIKE TO STEER!

So now you have a bike with minimal spring preload front and back, and if done at Suspension101, you have a larger amount of shock spring preload lift available as we use custom variable rate springs on most adv bikes.

Going on a BDR? Load up exactly as you are going to travel and GET THE BIKE TO STEER!

Use both rear spring preload adjuster and forks up in the triples if needed.


STATIC SAG... A FLACCID ATTEMPT TO ASCERTAIN HOW MUCH SPRING PRELOAD YOU HAVE


WITHOUT ACTUALLY CHECKING HOW MUCH SPRING PRELOAD YOU HAVE!!!



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