Spring rate help

nytsmaC
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nytsmaC
I’ve got a 5.6kg shock spring, my static sag is 28mm and my rider sag is 115mm without riding gear. I’d like to be around 102-105mm geared up with static around the 30-35mm range. Will a 5.8 get me there or do I need a 6.0?
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Factor E
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Factor E 9/15/2020 6:41pm
9/15/2020 6:41pm Edited Date/Time 9/15/2020 6:43pm
Stock valving or Revalved?
What bike?
Type of riding?
Ht- Wt
m21racing
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m21racing 9/16/2020 8:46am
9/16/2020 8:46am
On first glance I would say 6.0. How much preload is on the current spring to get the numbers you have?
davidgrip
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davidgrip 9/16/2020 10:17am
9/16/2020 10:17am
nytsmaC wrote:
I’ve got a 5.6kg shock spring, my static sag is 28mm and my rider sag is 115mm without riding gear. I’d like to be around 102-105mm...
I’ve got a 5.6kg shock spring, my static sag is 28mm and my rider sag is 115mm without riding gear. I’d like to be around 102-105mm geared up with static around the 30-35mm range. Will a 5.8 get me there or do I need a 6.0?
Add preload! Static and 28 mm means the spring is to stiff. Turn your preload to 102-105 race sag, then check your static. Do not buy a new spring till you get this one tested correctly. Also check your manual for correct adjustment range. Spring rates are usually 15lb increments. Correct spring in the correct position is key.


m21racing
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m21racing 9/16/2020 10:34am
9/16/2020 10:34am
You should be something like 35 to 45mm staic, with 102 to 105mm sag, and 5 to 8mm preload on shock spring.

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nytsmaC
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nytsmaC 9/16/2020 1:46pm
9/16/2020 1:46pm
Haven’t measured preload on the spring yet, new bike and haven’t touched it other than measuring sag. It’s a 2020 TM 300MX.

Davidgrip, I can add preload to reduce my rider sag to 105mm but my I’d have very little if any static sag left, the spring is too soft, not too stiff.

davidgrip
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davidgrip 9/16/2020 2:35pm
9/16/2020 2:35pm
nytsmaC wrote:
Haven’t measured preload on the spring yet, new bike and haven’t touched it other than measuring sag. It’s a 2020 TM 300MX. Davidgrip, I can add...
Haven’t measured preload on the spring yet, new bike and haven’t touched it other than measuring sag. It’s a 2020 TM 300MX.

Davidgrip, I can add preload to reduce my rider sag to 105mm but my I’d have very little if any static sag left, the spring is too soft, not too stiff.

Adding preload increases static sag. You will be close with the stock spring, once you set your rider sag.
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nytsmaC
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nytsmaC 9/16/2020 3:42pm
9/16/2020 3:42pm
davidgrip wrote:
Adding preload increases static sag. You will be close with the stock spring, once you set your rider sag.
I’m pretty sure you’ve got it backwards, increasing preload on the spring reduces static sag, unless I’m having a major brain fart here.
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davidgrip
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davidgrip 9/16/2020 3:58pm
9/16/2020 3:58pm
nytsmaC wrote:
I’m pretty sure you’ve got it backwards, increasing preload on the spring reduces static sag, unless I’m having a major brain fart here.
It happens. No preload =longer spring/less sag. More preload= shorter spring/more sag. I had a 16 KX450 with a 52 spring. Bought a 19 and could not get the correct sag, not researching that it now had a 54 spring. Set your rider sag and see where you are.
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FFDan
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FFDan 9/18/2020 11:28am
9/18/2020 11:28am
Read this, it may help you understand.

Remember the bike manufactures, general, spring the suspension for the average weight of the riders, which I believe I read about 180 pounds. If you happen to be a vet guy just out having some fun, like me, you can get away with with being a little "off" on the spring rate and get your sag close. However, 115 is a lot of race sag and the static is well off too. So, without knowing your weight and skill level it will be virtually impossible to say which spring rate will work for you. I went from the stock 5.5 to a 5.8 rear spring on my KX 450 the week after I bought it. But, Im 215 pounds and close to 220 with all my gear on.

https://motocrossactionmag.com/bare-bones-how-static-sag-can-help-you-c…

davidgrip
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davidgrip 9/19/2020 7:44am
9/19/2020 7:44am
Sorry. Backwards/reversed. Less static to soft/ More static to stiff. I just started to type it wrong again. I check my body weight every ride, and write down bike/track details. I set the bike up to be balanced and I adjust my technique to the conditions.

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