guidlines for setting sag?


12 replies to this topic
  • Boonie

Posted March 16, 2005 - 12:33 PM

#1

Here's what I think I know (or have read) about setting sag:

-- You want the sag between 100-105 mm

-- You measure sag from the rear axle bolt to the bolt on the seat

-- the rider must sit with full weight on the bike while a partner measures the distance

-- sag is adjusted via tightening or loosening the rear shock spring.


Is this accurate? I've never checked it and want to.

Also, are the measuring points consistent for most dirtbikes? Because I would think different makes with different frame geometry might result in different recommended sags instead of the universal 100-105mm. Or are the differences minimal?

any comments about the accuracy or inaccuracy of my data would be greatly appreciated.

Thanks.

  • RichBaker

Posted March 16, 2005 - 12:49 PM

#2

Correct...but you also want to check static, or unladen sag. Do it the same way as above, but off the ground , suspension unloaded, after you've set "race" or loaded sag. Less than 10mm and your spring rate is too light, more than 25mm and the spring rate is too hard. It's a good way to verify you have the correct rate soring for your weight. It doesn't matter which points you measure from, as long as it's the same points every time.

  • Boonie

Posted March 16, 2005 - 01:33 PM

#3

Thanks Rich but I have a question. Everything I read mentions "standard" sag numbers of around 100mm yet, you mention you can measure from any points as long as it's consistent. What if I pick ,say, the axle bolt to the lower sub-frame bolt and it measures 89mm. How do I know if that's accurate sag if the standard is 100mm?

  • RichBaker

Posted March 16, 2005 - 03:52 PM

#4

As long as you use the same points each time it won't matter...you are concerned with the difference between the unloaded meas. and the loaded meas.
On rereading your original post, I missed that you didn't meas. the unloaded, wheels in the air measurement. You must make all 3; unloaded, bike sitting on the ground, bike+rider on the ground. Your "race" sag = unloaded-(bike+rider) and unladen sag=unloaded-bike on ground .... HTH

  • Bamster

Posted March 17, 2005 - 07:04 AM

#5

There is a really good video half way down this page.
http://www.odsc.on.c...eo_diaries.html

  • Boonie

Posted March 17, 2005 - 07:53 AM

#6

Now it makes sense..........thanks.

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  • Jeremiah

Posted March 17, 2005 - 08:19 AM

#7

Great video. Thanks for the info.

  • Bamster

Posted March 17, 2005 - 12:37 PM

#8

When you have the bike on a stand your ready to turn the 2 lock rings.Use a punch and a hammer (if you don't have the spanner wrench). Back off the locking ring ( top ring). With good pair of gloves grab the spring and bottom ring and twist in the proper direction.It's to hard to turn just the ring.

  • Jeremiah

Posted March 17, 2005 - 12:44 PM

#9

I'll have to look at it when I get home, but how exactly do you use a hammer and a punch on this ring?!?

  • Bamster

Posted March 18, 2005 - 06:36 AM

#10

Place the punch on one of the tabs of the ring so that when you hit the punch it will turn it counter clockwise. this will loosen it.

  • Dan_from_HB

Posted March 18, 2005 - 08:46 AM

#11

Fitting the right spring is very important.
Without writing a book, I just want to caution you to set race sag first, then do static sag. If you are at 100-105mm race sag (while sitting on the bike), and you have between 15 and 20mm of static sag(while you are off the bike), your spring is OK. If you have less than 15-20mm, or if it tops out without your weight, you need a stiffer rate spring. More than that, and you need a softer rate spring. Yes, you read that right. No, I didn't mean the other way around.
You will not be able to properly adjust the wrong spring for both race sag and static sag.
This will help almost everyone select the correct spring rate for their weight. If you are Ty Davis (very stiff springs) or Ricky Carmichael (very soft springs), or if you are a jumper, you may want to customize. Otherwise, this will work. It will also give you a wide range of adjustment on your damping settings, whereas the wrong spring rate causes you to compensate with weird damping settings.

  • Bamster

Posted March 18, 2005 - 10:40 AM

#12

Dan didn't watch the video. It explained all that in there.

  • Dan_from_HB

Posted March 20, 2005 - 04:59 PM

#13

Dan didn't watch the video. It explained all that in there.


LOL. I didn't watch THIS video, but I've done it so many times now I can almost do it in my sleep.
Just wanted to give 'em a quick start guide.




 
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