Setting Sag...heard talk about it at Strats 7/25 - Chicagoland Sportbikes
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post #1 of 6 (permalink) Old 07-26-2007, 03:42 PM Thread Starter
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Setting Sag...heard talk about it at Strats 7/25

As I was milling around at Strats yesterday, I heard a few conversations about peoples experiences track riding and the most frequent question I head was "how do I set sag". Did a little digging around and this seems like the best explaination I have read from a Stickey on R6Forum.com:

SETTING STATIC SAG (THE RULE OF THUMB METHOD)

Static sag or free sag as some call it is what the bike own weight (without rider) compress the springs...

Rider sag is with the rider on the bike.


Assuming you now have the proper spring rate for your weight, you can now set your static sag. This method of checking static sag is not the definitive end all to suspension set-up but it will get you in the ballpark. Individual bikes will vary. For example, some bikes may work well with 25mm of sag in the front forks while others work better with 30mm of sag. This rule of thumb method has been the racer's basic set-up guide for over a decade and is still used today.

HOW TO:

Measuring the static sag of your bike is done with you on it. This will take several people to do. One person to hold the bike steady, the other to do the measuring. And then, there is you sitting on the bike with your feet on the pegs.

REAR: First, with you off the bike, lift up on the back of your bike or subframe to top out the suspension then measure from the ground to a chosen point on the tailsection or subframe like a metal bracket. (Make sure it's something solid. The plastic tailsection can flex and you will get inaccurate measurements.) Write down this measurement. Next, with someone stabilizing the front end, sit on the bike, feet on the pegs, kickstand up. Now, have the other person measure the height from the ground to the same spot on the tail section. The proper static sag with you on the bike shoud be 1 to 1 1/4 inch. If your spring is over or under-preloaded, it will make your bike perform poorly in numerous ways. If it sags too much or is topped-out, adjust it accordingly to the prescribed measurement.

FRONT: Place a zip-tie around the slider next to the dust seal. With someone stabilizing the rear end, sit on the bike, feet on the pegs and kickstand up. Let the bike sag naturally. Don't bounce up and down. That will cause the zip tie to slide further and give you an inaccurate measurement. Next, get off the bike, lift up on the bars (handlebars or clip-ons) and top out the forks. Measure the distance from the inside of the zip-tie to the dust seal. It should be about 1 to 1 1/4 inch. Adjust the pre-load accordingly to the prescribed measurement. This is your initial set-up.

Being that I heard a few people talking about it with the same questions, figured I would post up my findings so far.......feel free to suggest other ways/point out any inaccuracy

Last edited by [email protected]; 07-26-2007 at 03:44 PM.
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post #2 of 6 (permalink) Old 07-26-2007, 04:28 PM

 
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You can't measure the sag from the ground as you stated when doing the rear. You need to measure from somewhere on the tail of the bike, down to a place on the swing arm. If you measure from the ground and lift up the bike, the numbers will differ as to how high you lift the rear off the ground.

You didn't even measure static sag in the front.

Check out these sites for more information on suspesion and initial setup.
http://www.onthethrottle.com/v2/
http://www.feelthetrack.com/
http://www.traxxion.com/

If you search this site, I'm sure there other step by step instructions around.

There is a bit more that goes into this then is stated in your list. It's also possible that you can't set sag properly on the bike. In this case you need to start changing springs as well. If you don't know what all the knobs and screws on your suspension do and how they affect your suspension, get some help from someone that does.



Quote:
Originally Posted by BoostnGTI02 View Post
As I was milling around at Strats yesterday, I heard a few conversations about peoples experiences track riding and the most frequent question I head was "how do I set sag". Did a little digging around and this seems like the best explaination I have read from a Stickey on R6Forum.com:

SETTING STATIC SAG (THE RULE OF THUMB METHOD)

Static sag or free sag as some call it is what the bike own weight (without rider) compress the springs...

Rider sag is with the rider on the bike.


Assuming you now have the proper spring rate for your weight, you can now set your static sag. This method of checking static sag is not the definitive end all to suspension set-up but it will get you in the ballpark. Individual bikes will vary. For example, some bikes may work well with 25mm of sag in the front forks while others work better with 30mm of sag. This rule of thumb method has been the racer's basic set-up guide for over a decade and is still used today.

HOW TO:

Measuring the static sag of your bike is done with you on it. This will take several people to do. One person to hold the bike steady, the other to do the measuring. And then, there is you sitting on the bike with your feet on the pegs.

REAR: First, with you off the bike, lift up on the back of your bike or subframe to top out the suspension then measure from the ground to a chosen point on the tailsection or subframe like a metal bracket. (Make sure it's something solid. The plastic tailsection can flex and you will get inaccurate measurements.) Write down this measurement. Next, with someone stabilizing the front end, sit on the bike, feet on the pegs, kickstand up. Now, have the other person measure the height from the ground to the same spot on the tail section. The proper static sag with you on the bike shoud be 1 to 1 1/4 inch. If your spring is over or under-preloaded, it will make your bike perform poorly in numerous ways. If it sags too much or is topped-out, adjust it accordingly to the prescribed measurement.

FRONT: Place a zip-tie around the slider next to the dust seal. With someone stabilizing the rear end, sit on the bike, feet on the pegs and kickstand up. Let the bike sag naturally. Don't bounce up and down. That will cause the zip tie to slide further and give you an inaccurate measurement. Next, get off the bike, lift up on the bars (handlebars or clip-ons) and top out the forks. Measure the distance from the inside of the zip-tie to the dust seal. It should be about 1 to 1 1/4 inch. Adjust the pre-load accordingly to the prescribed measurement. This is your initial set-up.

Being that I heard a few people talking about it with the same questions, figured I would post up my findings so far.......feel free to suggest other ways/point out any inaccuracy

Greg K.
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Last edited by gkotlin; 07-26-2007 at 04:32 PM.
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post #3 of 6 (permalink) Old 07-26-2007, 04:35 PM
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one important note here is when measuring for rear sag measure to the center of the rear axle, that is where the sag must be taken from, also do a search on this site or www.nesba.com about setting your sag, tons of good info already out there
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post #4 of 6 (permalink) Old 07-26-2007, 04:35 PM

 
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A quick search turned up this article with photos.

http://www.sportrider.com/tech/146_9508_tech/

Greg K.
STT Staff Member
CCS Expert #12
MSF Instructor

VinylSaurusRex.com - Cyclepath Racing - Safety First Racing - SMR Components - Apexjunkie.com - Yamaha Champions Riding School
"If you're headed toward trees, I'm guessing your on the wrong line." - S. Russell
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post #5 of 6 (permalink) Old 07-26-2007, 09:24 PM Thread Starter
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Awesome, thanks for the info guys. Good riding with you jkrueger from Woodfield to Strats yesterday. I was 3rd in line behind Mort82 who was behind you.
post #6 of 6 (permalink) Old 07-26-2007, 09:42 PM
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