Static and Rider Sag questions



5 replies to this topic
  • gcally

Posted September 01, 2013 - 04:35 PM

#1

I have some static and rider sag questions.


After some research on the forums it looks like most people in the WR section recommend the following.
Static Sag – 25 mm
Rider Sag  - 100 mm

But when I look at the suspension portion of the TT forums they recommend the following for most rear linkage setups.
Static Sag - 34-35mm (+-2mm)
Rider Sag -  107mm (+-2mm)

Why would the base line setup be so different between the suspension forum and the WR forum?
 



  • RMK800

Posted September 01, 2013 - 07:11 PM

#2

I'm only guessing but I know from the 2010 and older a lot of riders think the suspension is too soft. Maybe they do less sag. Everything I have read says to set it at 4inches with all your gear and go from there with fine tuning adjustments...clickers, valves, fork oil level, springs, etc.

  • Krannie McKranface

Posted September 01, 2013 - 11:59 PM

#3

I have some static and rider sag questions.


After some research on the forums it looks like most people in the WR section recommend the following.
Static Sag – 25 mm
Rider Sag  - 100 mm

But when I look at the suspension portion of the TT forums they recommend the following for most rear linkage setups.
Static Sag - 34-35mm (+-2mm)
Rider Sag -  107mm (+-2mm)

Why would the base line setup be so different between the suspension forum and the WR forum?
 

 

 

The 25/100 is the 'magic number' that is your baseline.

It is not a final number.

There is no way anyone can recommend your sag for you without knowing at least the following other information:

 

Rear tire size

Fork position in clamps

Your weight and height

Sitting or standing up

Hard throttle or soft throttle

Front tire size and type 

etc

etc

 

..and even then, it starts to become personal preference to a degree.

 

 

The goal is to get the suspension and steering geometry as neutral as possible, or, tuned to your preferences.

 

Start with 25/100 and forks at the top of the clamps. Keep tire pressures consistent. 

Get to know that setting for a while, then make a change to the sag (less than 100) or the fork position (2-5mm up) and try that out.

 

You will find the guys in the WR forum to be good.

If you need more than that, and can articulate your needs, the suspension forum is a good place to go.
 

 

When the suspension and steering geometry are working together, the bike takes on a 'sweet spot' that make riding more intuitive and requires much less rider input to ride the bike.



Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • YamaLink

Posted September 09, 2013 - 06:23 PM

#4

And to add to the great input already written, some riders throw all the sag numbers out the window when it comes to long muddy races. It's important to get a baseline and adjust based on personal preference for the trail or track of the day.



  • gcally

Posted September 10, 2013 - 05:36 AM

#5

The 25/100 is the 'magic number' that is your baseline.

It is not a final number.

There is no way anyone can recommend your sag for you without knowing at least the following other information:

 

Rear tire size

Fork position in clamps

Your weight and height

Sitting or standing up

Hard throttle or soft throttle

Front tire size and type 

etc

etc

 

..and even then, it starts to become personal preference to a degree.

 

 

The goal is to get the suspension and steering geometry as neutral as possible, or, tuned to your preferences.

 

Start with 25/100 and forks at the top of the clamps. Keep tire pressures consistent. 

Get to know that setting for a while, then make a change to the sag (less than 100) or the fork position (2-5mm up) and try that out.

 

You will find the guys in the WR forum to be good.

If you need more than that, and can articulate your needs, the suspension forum is a good place to go.
 

 

When the suspension and steering geometry are working together, the bike takes on a 'sweet spot' that make riding more intuitive and requires much less rider input to ride the bike.

 

 

Thanks for all the info!!! Totally makes sense.

 

One question though….
I wonder why the Off-road industry does not have adjustable ride height on the rear shock. Coming from a road racing background rear shock length is adjustable without having to change your desired spring preload. 
Maybe it is because dirt bikes have so much more travel than a road race bike.



  • grayracer513

Posted September 10, 2013 - 02:06 PM

#6

107/34-35 are Dwight Rudder numbers.  Those work for him on his bike for the kind of racing he does, and for the bikes he sets up for others.  Each individual will vary some as to what they and their particular make/model likes best.  The numbers are important in this way: 

 

The rider sag should be "about" 25% of travel so that there is 3/4 of the travel available for compressive loads and 1/4 available to allow the bike to float over inconsistencies without loosing contact with the surface as much, letting the wheel drop into the low spots, as it were.  This dimension is important to the proper operation of the suspension.

 

Free sag gives an indication as to the correctness of the spring rate.  Once the race sag has been set, too little free sag means too soft a spring, too much indicates a spring that's too stiff.  That seems backward at first, but the reason it works that way is that when comparing with an "ideal" spring, one that's too soft will require more than the normal amount of preload to carry the rider weight, which will reduce the free sag, while a too stiff spring will need to be backed off to get the rider sag low enough, and that will add to the free sag.  The application the bike is being put to will have an influence on rate choice, too, and personal preferences come into play here as well. 

 

They aren't "hard" numbers, in the end, just a place to start from when tuning your chassis.






 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.