Which spring is stiffer 350 x 2.8 or 350 x 3.25?
- Thread starter fullmoto
- Start date
Run the spring that fits your shock. Running too short of a spring can lead to VERY bad things.
-KT
-KT
To attempt to clarify what others have already pointed out... Both of the springs you have should be the same "stiffness" as the spring rate is the same on both ie 350lb, this means that it takes 350lbs to compress the spring one inch, the second number is the stroke of the actual shock.
Due to the design of the suspension one may feel stiffer than the other but that's a whole other can of worms.
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yea but:
350 / 3.25 = 107.69230769230769230769230769231
350 / 2.8 = 125
i think division is more applicable here because these are compression shocks, not pull shocks like the old RS Super Dee Lux (shorter = division, longer = multiplication), so the shorter one is stiffer
This thread is full of fail. Each spring will take 350 lbs to compress 1". So, both spring will require the same effort to compress them the same amount. The only thing is that the shorter spring will bottom on itself sooner so it cant absorb more load.
No spring is stiffer.
No spring is stiffer.
Depends.
Are they feathers from a small bird or a large one?
I always used to answer, how long is a piece of string, until I was put in my place with the answer:
Twice the length from the middle to one end!
There are no stupid questions, just stupid people.
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I think the kid is asking about which one will result in more sag for the same weight rider.
If that's the case, for a bike with the same amount of wheel-travel, and a rider of the same weight, the 350# x 2.8 will result in a softer ride with its accompanying 2.75" stroke shock and higher leverage ratio.
The required spring rate will vary for the same sag percentage and rider weight as the leverage ratio changes. I'm not sure what the travel is on either Glory, but if the new one is the same as the old bike, you'll probably want to increase the spring rate. That said, different shocks can have different effects on spring rate, and if you were running a DHX 3/4/5 before and are on a DHX RC4 now, you'll probably use the same spring rate as the DHX RC4 requires a lower spring rate, all things considered, than the DHX 3/4/5 did.
Make sense?
There's spring rate calculators online that will help you with your spring rate selection. I like the one on TF Tuned's site. It won't be perfect, but it's a good starting point.
**Also, not saying you are, but make sure you're using the right length spring for the shock. Don't mix different stroke shocks with different length springs**
I think the kid is asking about which one will result in more sag for the same weight rider.
If that's the case, for a bike with the same amount of wheel-travel, and a rider of the same weight, the 350# x 2.8 will result in a softer ride with its accompanying 2.75" stroke shock and higher leverage ratio.
The required spring rate will vary for the same sag percentage and rider weight as the leverage ratio changes. I'm not sure what the travel is on either Glory, but if the new one is the same as the old bike, you'll probably want to increase the spring rate. That said, different shocks can have different effects on spring rate, and if you were running a DHX 3/4/5 before and are on a DHX RC4 now, you'll probably use the same spring rate as the DHX RC4 requires a lower spring rate, all things considered, than the DHX 3/4/5 did.
Make sense?
There's spring rate calculators online that will help you with your spring rate selection. I like the one on TF Tuned's site. It won't be perfect, but it's a good starting point.
**Also, not saying you are, but make sure you're using the right length spring for the shock. Don't mix different stroke shocks with different length springs**
the longer spring will make your bike heavier than needed if you have a 2.75 stroke shock. other wise they should feel the same. the longer spring will have extra coils that just add fat to your bike, the opposite of going to a ti spring, again, if you are going to the 2.75in stroke shock.
here an observation which might not be true. Doesn't the spring (when compressed) have a certain progressiveness inheritated to the material properties? Cause, if you compress a shock, the spring will only compress so far... but how, if Im constantly applying the same force? why does it not compress all the way as you have stated? So, if you have a longer strock spring, versus a shorter strock spring with the same lbs/inch stiffness, in matters of distance, you would bottom out the shorter one first, making the feel a bit more progresive since the longer one still has "available" travel, thus resulting in the shorter strock feeling "stiffer" or more progressive.... bare with me, does this make any sense?
So, by the previous logic, the shorter one would feel stiffer, and the longer one more linear.
So, by the previous logic, the shorter one would feel stiffer, and the longer one more linear.
i will bite (avoiding staining the stairs at the moment...):
you had a 350 on a 9" travel, 3 in stroke bike (ie 3:1 ratio), that is 116.7 pounds per 1 inch of wheel travel (350 pound per inch of shock movement)
now have a 350 on a 8" travel, 2.75 inch stroke (ie. 2.9:1 ratio) which equals 120.7 pounds per 1 inch of wheel travel.
so the 350x2.8 will *feel* slightly stiffer... which you need since its a shorter travel bike.... and therefore, they will ride very similarly.
the above is an approx, since the shock curve changes through the travel, and its nearly imposible to forecast exactly what your sags will be, but the curves between an 08 and 10 glory should be fairly similar, so the result should be about the same.
you had a 350 on a 9" travel, 3 in stroke bike (ie 3:1 ratio), that is 116.7 pounds per 1 inch of wheel travel (350 pound per inch of shock movement)
now have a 350 on a 8" travel, 2.75 inch stroke (ie. 2.9:1 ratio) which equals 120.7 pounds per 1 inch of wheel travel.
so the 350x2.8 will *feel* slightly stiffer... which you need since its a shorter travel bike.... and therefore, they will ride very similarly.
the above is an approx, since the shock curve changes through the travel, and its nearly imposible to forecast exactly what your sags will be, but the curves between an 08 and 10 glory should be fairly similar, so the result should be about the same.
-kx ... where K is the spring rate and x is the material constant (i think, been a while since high school physics). so if its steel, its the same the spring constant is the same, if its ti, the spring constant is slightly different, since its a different metal (and why people fee ti rides a little nicer).
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you guys are forgetting to use Pie to figure out the stiffness difference
gona go with the brick OBRIOUSLY~~~!!!!!!
those are spermies ^^^^^^^
ride your bikes quit worrying.
Yeah but 107.6 = 10 + 7 + 6 = 23
First part.... perfect sence
second part,..... not so much...
350lbs of force per inch, at full bottom out both springs on the same shock will take the same force exerted on them at that point. IE they would at 2.75 inches of stroke<the most the shock will allow> both have 962.5 pounds of force on them<at the shock>
Even though they are identical spring rates the 350/2.8 on an 8" travel bike would feel ever so slightly stiffer than a 350/3.25 on a 9" travel bike due to the difference in leverage ratio (assuming identical leverage curves.)
What you need to do is calculate the wheel rate:
Wheel rate = (ratio)squared x spring rate
1/3 squared x 350 = 38.88 lb/in
1/2.9 squared x 350 = 41.61 lb/in
But yes- on the same model year bike with the same leverage curve they will feel the same for a given amount of travel. Changing the length of the spring will not change the wheel rate.
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where is DaveP when you need him 
drops to flat are softer when you go faster.
Jesus H f&*ng christ, what the hell kind of nutmeg are you drongo's smoking?
A coil spring operates solely in the hookean region of steal, ie, the thing is as linear as it gets, discounting the change in drag from spring rotation on a longer spring (the thing those obtainium needle bearing kits try to eliminate)
In other words, if the a 350x3" spring is the same stiffness as a 350x2.5" spring, they both take 350lb to compress the spring 1". It doesn't change right to the very end. The end.
I know some of you were being sarcastic, but Jesus some of you are serious as cancer.
A coil spring operates solely in the hookean region of steal, ie, the thing is as linear as it gets, discounting the change in drag from spring rotation on a longer spring (the thing those obtainium needle bearing kits try to eliminate)
In other words, if the a 350x3" spring is the same stiffness as a 350x2.5" spring, they both take 350lb to compress the spring 1". It doesn't change right to the very end. The end.
I know some of you were being sarcastic, but Jesus some of you are serious as cancer.
I had some delicious rhubarb pie last night but when I tried to use it for stiffness calculations it just made a mess.
Mmmmmm. Have you every tried rhubarb pie w/strawberries baked in it too? Absolutely deliciousI had some delicious rhubarb pie last night but when I tried to use it for stiffness calculations it just made a mess.
I doubt the addition of strawberries to the Pie will make it any less messy when using for any type of calculations however. 
you needed to use apple Pie to figure the stiffness ratio outI had some delicious rhubarb pie last night but when I tried to use it for stiffness calculations it just made a mess.
yup, I failed to mention the rhubarb pie I was using was a strawberry rhubarb pie.
It was still warm from the oven when I bought it!
As an engineer this thread made me cry.
As a banana, this thread made me Thursday.
Keep your pie habits and how they affect your stiffness to yourself bub.I had some delicious rhubarb pie last night but when I tried to use it for stiffness calculations it just made a mess.
I am also and engineer, and this thread made me laugh my a$s off several times.
Your mom likes bananas.
this thead is lacking in ludacris content.
"It's not a question of where he grips it! It's a simple question of weight ratios! A five ounce bird could not carry a one pound coconut."
African or European?
African Bird, European Coconut.Huh? I... I don't know that.
Classic...