SuPer DavE...sag#s

[Speedballer347]

Dave what do you reccomend for front/rear free and rider sags?
I am going w/ 10mm rear and 20mm front free sag.  What do you recomend for rider sag#s.

Thanks! 8)

[Super Dave]

Check your e-mail...

[Sunny]

Front: 20-23mm free sag/target 35mm rider sag (stiffer spring yields more free sag and the softer spring yields less free sag)

Rear: Target 10mm free sag/30-35mm rider sag (stiffer spring yields less rider sag and the softer spring yields more rider sag)


Pay attention to which sag I recommended to target for the front and rear!  Read, get the sag (free or rider) to match the recommended number exactly with the other sag (rider or free, respectively) to fall in the range I recommended!

[Speedballer347]

Thanks Fellas! 8)

[motomadness]

Sunny,

Rider sag and free sag aren't inversely proportional.

Why would a softer spring yield less free sag?  Is it because you have to crank the "pre" load down so far to get the correct rider sag that the spring cannot relax enough to provide adequate free sag?  

A spring is a spring whether it's in the rear or the front.  Preload is just what the name suggests, "pre" load.  Therefore a softer spring requires more preload to reduce rider sag to the desired range.  A stiffer spring requires less preload to tune the rider sag, and therefore has more free sag.

[Sunny]

Pay attention to what I posted!   ;D


I said, target the front with a 35mm rider sag, and make sure that your free sag are basically with the 20-23mm range.  When out of this range, you can use what I said about yielding more and less free sag to determine whether or not your fork springs are too stiff or too soft.  For the rear, target the free sag at 10mm, and make sure your rider sag are with the recommended range I suggested.  When out of this range, you can use what I said about yielding more and less rider sag to determine whether or not your fork springs are too stiff or too soft.  Of course, you can target at a 30mm rider sag for the rear, and make sure your rider sag are in the range of 5-10mm instead.  Max McAllister of Traxxion Dynamics likes more free sag at the rear and 10mm is what he recommends (stiff spring than those using 5 mm of free sag with similar rider sag).  

These recommended sag numbers are what I gathered from Max McAllister of Traxxion Dynamics and other sources from research.

[Sunny]

Why would a softer spring yield less free sag?  Is it because you have to crank the "pre" load down so far to get the correct rider sag that the spring cannot relax enough to provide adequate free sag?  

A spring is a spring whether it's in the rear or the front.  Preload is just what the name suggests, "pre" load.  Therefore a softer spring requires more preload to reduce rider sag to the desired range.  A stiffer spring requires less preload to tune the rider sag, and therefore has more free sag.

You are correct!  The purpose of measuring sag is to make sure that you have correct/desireable spring rate for your suspension to get the best out of it.  Using too much pre-load on a "too soft" spring to obtain the desired rider sag will not give you enough free sag as you explained.  On the other hand, using basically no pre-load at all on a "too heavy" spring to get enough free sag but will not yield enough rider sag.  You want both rider sag and free sag to be in a certain range to be sure of that you have the right springs (a scientific method of checking for correct spring rate)!  Of course, some bikes work best using softer or much harder springs, but in general, most sportbikes follows the scientific method pretty close for correct spring selection.

[motomadness]

I wasn't saying you were wrong.  I mainly replied because you made two different statements for the front and rear springs.  I understand the statements were different because one discusses rider sag, the other free sag, but I didn't think your explaination was clear as to the direction you were going.  I was just trying to fill in the gap.

[Sunny]

My bad..........  But no offense intended here (see the smile face I used?)!  As I said, you are correct in your statement, and I just want to make sure whoever read my post/s know exactly what I was talking about!    ::) ;D

[Super Dave]

 The purpose of measuring sag is to make sure that you have correct/desireable spring rate for your suspension to get the best out of it.

Preload will NOT change spring rate...unless you spring bind it...that doesn't change the rate, but screws it up.

If you had a spring that had a variable rate, it still wouldn't change the rate, but it would change when the heavier rate came in...