overbore

Member
Dec 24, 2001
362
0
I know this is going to be a real general question
that has been asked before,but I need to ask in
my own way.Generally isnt the springs front and rear
responsible for where the two ride in the stroke and
determine harshness or plushness with the dampning
adjustments reb and comp for fine tuning for small
deflections,cornering,and traction?and something that
I always wondered is does everyones suspension that
is set up correctly sag the same front and rear?And
is Race sag more important than static or the other
way around?
Thanks for any and all responses.
overbore :)
 

NO HAND

~SPONSOR~
Jun 21, 2000
1,198
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I'll take a shot at it. I think you are right that springs determine where the suspension rides in the stroke but are not mainly responsible for harshness or plushness. The hydraulic system (valving) takes care of that. The adjustments (comp. reb. clicker) will make a good system more versatile but won't make up for one that is poorly setup. With rider sitting on the bike, everyone's bike should be adjusted to sag approximately the same; usually it is 100mm rear and the front is more tricky to calculate, some say around 40mm front. The sag that matters most is the race sag-(with rider on bike). The static sag is just a way to confirm you have an acceptable spring rate for your weight.
 

overbore

Member
Dec 24, 2001
362
0
I have read and read and understand it and have rebuilt both shocks
and forks,but get out on the course and its hard sometimes to tell which
way to go to make it better.I am sure once its set most everyone leaves it
alone for the most part.But untill set right I need hints like I have read that
washing in turns has rebound to fast ect.how about compression,when is it
right?front and back and rebound for the rear?just set as soft as possible
and increase untill right or how does everyone do it?I know that rick mears
was the best at dialing a indy car in and I would hope to be able to do that
on a bike someday.
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
You need to go out and make big adjustments to get a feel for a really bad setup-then you will fine tune your senses to tell you whats wrong/right, just make sure you note down all settings before so you can go back at the end of the day.
 

overbore

Member
Dec 24, 2001
362
0
Thanks marcus for the reply.Someone else told me the same thing not long ago,but I
would rather learn without getting hurt,but will try this method this
spring.When you push down on a bike just sitting in the garage should both rebound
at the same rate so you know there even with the 100 in the rear and 40 in the
front?any help appreciated.or do you want a stager?I just recently read somewhere
that static sag on the ktm is more important than race sag whether thats true or not
I am not sure,but would like to be thinking the right way when I hit the field
again for my son mainly.
 

JTT

~SPONSOR~
Aug 25, 2000
1,407
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I'm gonna mirror what Marcus has said. Make big changes first to really feel the difference that each makes. Leave the 1-2 click adjustments till you get a much better feel.

Also try to be as consistant as possible when testing. That is to say, try the setting on the same portion of the track and same line. You should be intimately familiar with this track to start with, as this will help eliminate some of the variables involved. A video camera really helps, as you can slow down the playback and see, with more accuracy, what is really happening.

Get your spring rates sorted first though as this is the "foundation" of all your work. Sorry, can't help with PDS.

Keep good notes and back up each test with a stopwatch. Sometimes, what "feels" fast, is not actually fastest.

Patience is the key, both from the tuner and the rider. Riders tend to get bored with this type of testing very quickly...big difference between "factory" guys and many "normal" racers.

Sorry if this sounds wishy washy, but it really is a feel/ experience thing (and a bit of hocus pocus :think: ). There are some good tuning guides out there, MX Tech, as one example, that work well to help guide you, but will not be as straight forward as they often sound in real life. Use them as that, a guide. At least, with some luck, you'll be going the right direction :thumb:
 

overbore

Member
Dec 24, 2001
362
0
Thanks for the answer JTT.Your the best,you helped me last year on understanding
valving and how the flow works when I tore some of my suspension apart last year.
This is why this place is great.
overbore.
 

JTT

~SPONSOR~
Aug 25, 2000
1,407
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Glad to be of help my freind!...and glad it was some help to you.

Your right, this is truely a great place, but it's only made that way be the great people that hang out here from time to time :thumb:
 

georgieboy

Member
Jan 2, 2001
416
0
Ohlins advised frontsag to be around 70mm. I myself ride now with around 60mm of front sag. I feel most people ride front wheel high, and understeers in the corners.
 

NO HAND

~SPONSOR~
Jun 21, 2000
1,198
0
Georgieboy, I think you are right. you know what? the more I think about it, the more I think your 60mm front sag makes much more sense than my 40mm. I've read somewhere it should be one third of the travel if I'm right? So, 40mm wouldn't be logical really. I remember reading it though. It's true, it's true! :eek: . Seriously, there must be a magic number because sag numbers are so important in the rear, I still don't understand why no one bothers about front sag. I wonder if it is best to adjust by shimming the spring or by sliding the tube in the tripleclamp. shimming the spring must be best :think:
 

JTT

~SPONSOR~
Aug 25, 2000
1,407
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I think one of the main reasons front sag is not talked about more is that it is so hard to determine. By nature, forks have much more stiction and it is difficult to get consistant results. That said, I must say my Ohlins are the most stiction-less forks I've ever seen. :thumb:

NoHand, sliding the forks up in the clamps will not effect sag (at least to any significance), other than by putting a little more weight on the front end. To effect sag in front, you'll need to do the same as in the rear, more preload, or heavier springs.
 

georgieboy

Member
Jan 2, 2001
416
0
That's right JTT, sliding the forks in the clamps won't alter sag. But it is a important tuning device.
The 1/3 sag nbr is only for the rear. Front is less sag. The most told is 1/6 of the travel, but i find this a bit limited. Ohlins is more advicing 1/5 of full travel.
I measure sag with half a tank full. That way I try to get the best figure when dialing in. Stiction is a problem, but you can sheat a bit by pulling up the forks and let it settle down, and then push the forks down and let is come up. Use the middle mark as the sag.
 
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