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Discussion Starter · #1 ·
Note:  I am not an expert.  I have purchased the Traxxion DVD on setting suspensions
where stiction is described.  I did not implement that in the following procedure due to
lack of quality photos.  I will re-do this after getting feedback from board members and
then ask the moderators to make this into a "sticky".   THIS IS A WORK IN PROGRESS!
I AM JUST PUTTING A DRAFT UP TO SOLICIT FEEDBACK FROM MEMBERS.
++++++++++++++++++++++++++++++++++++++++++++++++++++++
(The picture quality is very bad due to a crappy point and shoot camera.
I will shoot those photos again with my new Nikon camera and resubmit)
================================================
It is possible for one person to set sag with this tool. 
However two people will do a faster and better job at it.
Two people are needed to account for stiction in measuring sag.

What you need:

White wire coat hanger
long nail (to be used as a mandrel to bend red hot wire around)
2 four inch zip ties
Vernier Caliper or a small 6 inch scale
Sharpie marker

Just about every resource I have seen recommends a tape measure for setting sag.
The problem with a tape measure is that one must use the same reference points each time.
Measuring with a tape measure is a form of relative measurement.  One measures from a
point on the swing arm to a point on the body. 

My method will replace that relative measurement method with an absolute measurement on a
fixed rod.  We will only focus on the sag measurement.  The distance of the swing arm will
become irrelevant.  (hang in there, the pictures will make it clear!)

OK, to build the tool.

Take the coat hanger and make it into a straight rod with a pair of linemans pliers. 
Do not remove the spiral where both wires were twisted together, we need that.

Cut off an 8 - 10 inch section of the coat hanger and insert most of it in a vise and
heat the wire with a propane torch and wrap it around a nail to make a loop like so:



Two loops will be enough.  Cut off the excess so you have a 6 inch piece of wire with
the two loops on the end of it.  This wire will go in the rear crack of the rear seat above
the axle.



Now take the long wire and bend a 90 degree angle with the end of hanger that has the
spiral impressions.  The leg should be at least 4 to 5 inches long. 
Insert that leg into the hollow of the rear axle. 



Insert the short looped wire into the long wire and place the short looped wire in the
crack behind the seat like so:



You may have to jam a piece of zip tie in the axle along with the wire to prevent any
up and down movement.  That wire must have no movement up and down for accurate
measurements. 



Put a zip tie above and below the looped wire.



You are now ready to measure sag.  There are two different kinds of sag. 

Static Sag = how much the bike sags under its own weight.  5 - 10mm is recommended.
Total Sag =  how much the bike sags under the riders weight.  30 - 35mm is recommended.

Note that Total sag is combined with Static sag to achieve that length.
The rider will sit on a bike that static sag is properly set in order to reach a proper total sag number.

There are two ways to get the initial reference point from which we will measure. 
One is to suspend the bike from the grab bar so that the tire is not touching the floor.
Second would be to compress the spring so much that there is no sag.  I prefer this method
because it gives you an idea of the effect the spring has on the suspension.
Verify there is no sag by lifting the grab bar after moving the top zip tie to the reference loop.
No sag will not allow the zip tie to slide any higher.  Mark the top of the zip tie with your Sharpie.




Now loosen the spring compression collar until you get 5 - 10mm of sag.
Note that you have to measure from the bottom of the top zip tie to the top of the wire loop.

Stiction is internal friction that must be accounted for when measuring sag.
One lifts the bike and releases it gently to get the upper measurement.
Then put as much weight as you can on the grab bar and gently release it.
Take the difference between the two measurements and split it in the middle.
This will be your accurate final sag measurement.

Static sag still has a little bit of a ways to go in this following picture:



Now the rider gets on and the spring is adjusted until one gets 30 - 35mm of total sag.
Again note that this measurement is made from the bottom of the top zip tie to the
top of the wire loop.  If you are alone, you have to subtract the thickness of the wire
loop from the measurement of the bottom ziptie.  This picture is oriented on its side to
illustrate the vernier calipers.  With a second person, use the above described stiction
procedure to get an accurate total sag number.



I made my measurements while on a rear stand till I got close to what I wanted. 
I then got dressed in my gear, removed the stand and got on and balanced the bike with
one hand on the work bench to get my final sag figures.


The front fork is much easier.  Put an 8 inch zip tie on one of the forks.  Then lift the front
end off the ground with a stem stand or lifting by the triple tree.  Do not use typical front
fork stands!  The front forks must be fully extended.  Use the vernier caliper to measure the
top of the fork seal to the bottom of the triple tree. 

Subsequent measurements are made from the bottom of the triple tree to the bottom of the zip tie.

Sag is adjusted by shortening the length of your spacers in the fork.  Final sag adjustments
are made with the preload caps on top of the forks.
 

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

thats pretty niffty idea
 

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

Okay, I just went through this procedure step by step. Twice, to make sure I did it right. It actually took me longer to print out the post and convert the mm to thousandths of an inch then to set it. The fact that the Sonic Springs instructions for spacer lengths were dead on for me helped tremendously, but I ended up on two lines showing on the preload caps and one half turn less preload on the Hagon to end up at the softer side of the sag limits.

Very good step by step Joe. Now go get those better pictures ;D Once you get it all finalized and reposted, I can turn it into a .pdf if you wish...
 

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Discussion Starter · #6 ·
Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

Thanks!

I will do that but it will be at least a couple of weeks.
I will be tied up pretty good between being on call and getting some classes started so I can finish my damn masters degree!

When my wife asked my if I was going to go for my PhD (piled higher and deeper ;D ), I told her that I would saw my leg off with a rusty old chainsaw first! :(

That's it ... no more school for me.
 

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

Nice write up, thanks!

Another nifty idea instead of using a clothes hanger you can buy a yard stick or metric yard stick and drill a hole in the bottom of it so that it is fitted with a small rod or screw/bolt that will fit inside the axle hole. Place the bolt in the hole and find a reference point on the bike and take the measurement off the ruler/yard stick then take your next measuremtn and subtract the two numbers. We use this method on our dirt bikes and works great. It's at my dads house or I would post a pic.
 
G

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

if you realy want to get tricky make set up that you can ride with and measure travel.
 

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

the way to do that is putt some grease or something like that on your shock/fork tube and see how far down it has been after a ride around teh block or down the road. Some use rubber bands or rubber o-rings by say taking the fork loose on the bottom and placing them over he end and up on the tube.
 
G

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Re: Setting Rear Shock Sag on the SV650 (FIRST DRAFT)

bbmxta said:
the way to do that is putt some grease or something like that on your shock/fork tube and see how far down it has been after a ride around teh block or down the road. Some use rubber bands or rubber o-rings by say taking the fork loose on the bottom and placing them over he end and up on the tube.
you can't use O-ring on rear.the best way is to do it with stick,something similiar what he did with sag but more solid.
there is place to buy it but not hard to make yourself.
 
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