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Race sag proper, Static sag, not, even with lower spring?

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I have a 2007 CRF 450 R, and I swapped over my 2005 CRF 450 R's rear shock with a 5.2 kg spring and trail tuned stack over, and put my trail tuned fork stacks and .44 springs in my new 07 forks.

I was measuring my sag and I noticed the following:

static sag is about1.5 inches - and race sag is 4 inches

Manual calls for .4-1.0 inches for static and 4 inches for race.

for reference, Im doing this by myself with my camelbak, so I'll get better race sag measurements, but it looks close, and I pulled the side panel off and am measuring from where the manual tells me - farest back point on the subframe to the machined part on the swing arm.

Here's the kicker - it says if the static sag is more the 1.0 inches but I achieve proper race sag, my spring is too high.

I'm probably 190 ready to ride, so do this sounds off? with a 5.2 spring when stock is 5.5? i havent measure'd my length of preload - manual says that i can't use more than 8mm of preload, which is about 6 turns max. I'm not quite sure how much I turned it before I put it on - but 6 sounds about right. Supposing I did 10 turns? would this give me the result's im getting, or the opposite?

guess i need to take the subframe off and measure the length of the spring?

also - notice that the resevoir of the shock can wiggle a lot - and the shock bolts are torqued to speck. is this play ok and normal?

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Well, your numbers sound great.

38mm static

101mm loaded

Thats pretty much 100% on the money.

I've never seen a manual that spells it out in inches properly, they usually mess up the translation. The whole industry is based on millimeter measurement not inches. If you have a few bux, pick up a Race Tech Sag tape measure, they're like $10 bux and have mm on them. :bonk:

But yea, doing the translation here, your numbers look great.

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Thanks Tye.

I guess my question is really to the fact that the manual calls for 6-25 mm of static sag, and yes, I am getting 38mm of sag.

am i correct in that my bike won't be returning to full travel since it's static sag is more than recommended?

I did some searching and found that some people are running 40mm of static sag, so am I ok? What are the drawbacks of having too much static sag?

manual says I need a stiffer spring if I have more than 25mm of static, but from what I can draw a conclusion to is the opposite. If I turn the preload UP and reduce race sag, my static sag as well reduces - so it seems like I'm using too much preload to attain proper sag - which I was trained that means the spring is too soft? wonder why the manual says if I have too much static SAG that my spring is too stiff?

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Don't sweat the static sag all that much. Ride it. See how you like it. You may end up backing the rebound clicker out one or two spots. The guide lines are just that, guide lines.

If you had proper race sag and 50mm of free...ok...the spring is too stiff. But 38 is pretty dang close. And depending on who's rule you choose to use, 10-40mm of free sag is dead nuts perfect.

manual says I need a stiffer spring if I have more than 25mm of static, but from what I can draw a conclusion to is the opposite. If I turn the preload UP and reduce race sag, my static sag as well reduces - so it seems like I'm using too much preload to attain proper sag - which I was trained that means the spring is too soft? wonder why the manual says if I have too much static SAG that my spring is too stiff?

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I think your confusing up...with the collar moving up on the shock, and the term up meaning increasing the preload.

If you need to increase the preload to achieve proper sag but still end up with too much free sag...the spring is too stiff.

And it really doesnt matter which way you have to turn the adjuster when your setting the sag. The final setting is what matters. Once youve achieved proper race sag, thats when you check the free sag.

And what I think we're finding is that thumpers seem to work better with a little more free sag than two strokes. The engine braking impacts the chassis on corner entry on the thumper where on the two stroke there's almost zero engine braking. When you get off the throttle on a two stroke the springs and your braking effort are what is affecting the chassis attitude. The thumper has the engine braking causing the front to try to dive a tad even before most guys get to the brakes.

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I guess my question is really to the fact that the manual calls for 6-25 mm of static sag, and yes, I am getting 38mm of sag.

The manual is wrong sadly. As I pointed out above, everyone in the motorcycle community uses mm as a measuring tool, including the Japanese guys who made your bike. Someone in Japan has to translate that into inches and they messed up. Woops!

am i correct in that my bike won't be returning to full travel since it's static sag is more than recommended?

Forget the manual's recommendation. ALL modern-linked MOTOCROSS bikes should run 40mm +/- 2mm of static sag and 105mm +/- 5mm of rider sag (depending on the track and what the rider prefers)

So you are right in that range perfectly.

I did some searching and found that some people are running 40mm of static sag, so am I ok? What are the drawbacks of having too much static sag?

The reason why you measure static sag is to get a rating on if the spring is the right stiffness. There are base numbers that everyone works with, which are industry standard pretty much. If your static sag is too much and your rider sag is perfect, your spring is still too soft, that is the only consequence.

manual says I need a stiffer spring if I have more than 25mm of static, but from what I can draw a conclusion to is the opposite. If I turn the preload UP and reduce race sag, my static sag as well reduces - so it seems like I'm using too much preload to attain proper sag - which I was trained that means the spring is too soft? wonder why the manual says if I have too much static SAG that my spring is too stiff?

Don't listen to the manual. If I listened to my manual, I'd still be trying to figure out how to make the bike start! LOL :bonk:

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OK, You need to get someone else to take your measurements unless you have a Motion Pro Uni-Sag. They work great.

Now it sounds like you are riding your Honda mostly offroad if you are using a camel bak so here is what I recommend. I have a formula that I use on all modern bikes.

Your shock spring preload should be less than 10mm on linkage suspension but not less than 5mm. You don't want to over preload a weak spring as you will just get a harsh ride that still will allow hard bottoming. I usually shoot for about 5mm preload on fork springs. If you have the right spring.

You can figure your correct sag numbers by using percentages. That way you can get the correct springs for you and your bike. Base these percentages on the available travel front and rear with a variance of + - 3 mm.

Front suspension static sag should be 14% ( available travel in mm X .14 = static sag in mm)

Front suspension rider sag should be 25% (X .25 = Rider sag)

Rear suspension static sag should be 11% of available travel (X .11 = static sag)

Rear suspension rider sag should be 34% of available travel (X .34 = rider sag)

Using these principles you can figure the correct sags for any bike and thus the correct springs without guessing and compromising.

Once you get the springs set correct you can get the forks and shock revalved if need be. I usually like to take 20-25% of the high speed compression out with the correct spring rates.

I usually leave rebound stock or change according to the replacement springs. I usually will change rebound one click per .2 kg. on rear shock. If I go up on spring rate say from a 5kg to a 5.8kg , I will go in 4 clicks. That is a good place to start. After setting rebound and spring sags (and getting correct spring rate installed). I find a G out or a ditch that I can jump into and expect to bottom front and rear at same time. I will back off compression till I am bottom softly front and rear. NOT DRIVING FOOTPEGS THROUGH YOUR FEET OR METAL TO METAL BOTTOMING.. Just bottoming softly. Then I go back in about 2 clicks to compensate for heated suspension. I then will ride extensively to see if I need to go in or out slightly to fine tune. Damping I find is a very personal thing it you take the time to dial it in. I like a plush and compliant suspension but not wallowy. Many times lately I find that I have to go down on fork springs and up on shock spring rates. I weigh 180-185lbs.

Your bike has 310mm of front fork travel. Static sag should be about 43mm and rider sag should be 77.5mm (Both + -3mm).

Your bike has 315mm of rear wheel travel Static sag should be about 35mm and rider sag should be about 107mm.

You can fine tune from there but you can get the correct springs for you and your bike with this formula. This is a bit more scientific way of figuring your spring rates than guessing.

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good info dwight. Never knew if the forks should be at a third. with mountain bikes - we run 1/3 in the rear and 25% in the front on level ground, so that things level out when going DH and so the fork doesn't dive as much etc.

I appreciate the tips.

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good info dwight. Never knew if the forks should be at a third. with mountain bikes - we run 1/3 in the rear and 25% in the front on level ground, so that things level out when going DH and so the fork doesn't dive as much etc.

I appreciate the tips.

Forks should be 25% of available travel in rider sag. I find that 34% gives me that best in handling on rider sag in the rear. If your static sag works out then you have the correct springs for you and your bike.

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Dwight whats your advice on a bike that is setup the way you suggest and you racing a GNCC style race with an MX track thrown in at the end or occasional track visit

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Dwight whats your advice on a bike that is setup the way you suggest and you racing a GNCC style race with an MX track thrown in at the end or occasional track visit

Springs should be close in any condition. Some seem to like a bit stiffer front for MX /SX but you can't get the bike to setup for and settle into turns without a berm. I like my bikes to turn. Damping is a personal choice for riding skill and type of racing. I like take out about 25% of my high speed damping so my suspension is more compliant over roots and rocks. The proper springs help keep bottoming under control even with the lighter damping. Many times I will go up a bit on my fork oil level to help with bottoming with the lighter damping.

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so you just spin your clickers to compete in a stage of MX track through in an enduro event??

Thanks

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I'm getting ready to set the sag on my KTM. I weigh about 220 in street clothes.

Your shock spring preload should be less than 10mm on linkage suspension but not less than 5mm.

Is there a different formula for non-linkage suspension?

Using these principles you can figure the correct sags for any bike and thus the correct springs without guessing and compromising.

Once the race and static sags are calculated is there a way to determine correct spring rates before wrenching on the bike? I've used the racetech spring rate calculator, but want to make sure this formula works with their calculations.

Excellent write-up. I copied and saved it as a word doc.

Edited by expl_eng
Added info.

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The RaceTech calulator is way wrong in most cases. So I have found.

On a KTM PDS you need a bit more static sag. You should be shooting for about 115mm (+-2mm) rider sag in rear with about 37-40mm static. Front forks are the same. One effects the other so always recheck when you get them set.

I'm getting ready to set the sag on my KTM. I weigh about 220 in street clothes.

Is there a different formula for non-linkage suspension?

Once the race and static sags are calculated is there a way to determine correct spring rates before wrenching on the bike? I've used the racetech spring rate calculator, but want to make sure this formula works with their calculations.

Excellent write-up. I copied and saved it as a word doc.

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Once you get the springs set correct you can get the forks and shock revalved if need be. I usually like to take 20-25% of the high speed compression out with the correct spring rates.

I usually leave rebound stock or change according to the replacement springs. I usually will change rebound one click per .2 kg. on rear shock. If I go up on spring rate say from a 5kg to a 5.8kg , I will go in 4 clicks. That is a good place to start. After setting rebound and spring sags (and getting correct spring rate installed). I find a G out or a ditch that I can jump into and expect to bottom front and rear at same time. I will back off compression till I am bottom softly front and rear. NOT DRIVING FOOTPEGS THROUGH YOUR FEET OR METAL TO METAL BOTTOMING.. Just bottoming softly. Then I go back in about 2 clicks to compensate for heated suspension. I then will ride extensively to see if I need to go in or out slightly to fine tune. Damping I find is a very personal thing it you take the time to dial it in. I like a plush and compliant suspension but not wallowy. Many times lately I find that I have to go down on fork springs (especially on MX bikes) and up on shock spring rates.

Once I have the springs selected and set. I adjust my damping for the 99% of what I encounter in an H/S or Enduro. I just bottom slightly a couple times an event. IF, I was intending to ride a MX only that weekend, I would probably go in a couple clicks on compression just for that event and then reset afterwards. I rarely adjust during an event unless needed. For a very sandy event I might go in once compression click. Before the event not during different sections.

so you just spin your clickers to compete in a stage of MX track through in an enduro event??

Thanks

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The RaceTech calulator is way wrong in most cases. So I have found.

On a KTM PDS you need a bit more static sag. You should be shooting for about 115mm (+-2mm) rider sag in rear with about 37-40mm static. Front forks are the same. One effects the other so always recheck when you get them set.

So how does one determine correct spring rate required?

Thanks for the info.

Numbers worked out pretty close using your equations compared to what you posted above:

Rear suspension static sag should be 11% of available travel (335 X .11 = static sag)

37mm +/- 3mm

Rear suspension rider sag should be 34% of available travel (335 X .34 = rider sag)

114mm +/- 3mm

Thanks again.

Edited by expl_eng
Added spring calculations.

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Ok so here's my question - and i totally appreciate your advice and time here man.

If I had a mechanic knock out some of the HSC, and he replaced the mid stack with a mid valve - he calls it a check valve, witih a spring. He also said that this affect both compression and rebound.

so if i've had this done, should i still go out 1 clicker on R since i went from a .5.5 to a 5.2 ? i know 1 clicker isn't going to change the bike that much, but just thought I'd geek out.

also he told me that he generally sends the suspension out the door 10 out on R and 12 out on C front and rear.

I usually leave rebound stock or change according to the replacement springs. I usually will change rebound one click per .2 kg. on rear shock. If I go up on spring rate say from a 5kg to a 5.8kg , I will go in 4 clicks. That is a good place to start. After setting rebound and spring sags (and getting correct spring rate installed).

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Sounds perfect !

So how does one determine correct spring rate required?

Thanks for the info.

Numbers worked out pretty close using your equations compared to what you posted above:

Rear suspension static sag should be 11% of available travel (335 X .11 = static sag)

37mm +/- 3mm

Rear suspension rider sag should be 34% of available travel (335 X .34 = rider sag)

114mm +/- 3mm

Thanks again.

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I suggest trying it as is on Rebound. Adjust your compression to taste. Back off till you are bottoming slightly and then go back in one or two clicks. You may find you need to go in another click on rebound if you back off much on compression.

Ok so here's my question - and i totally appreciate your advice and time here man.

If I had a mechanic knock out some of the HSC, and he replaced the mid stack with a mid valve - he calls it a check valve, witih a spring. He also said that this affect both compression and rebound.

so if i've had this done, should i still go out 1 clicker on R since i went from a .5.5 to a 5.2 ? i know 1 clicker isn't going to change the bike that much, but just thought I'd geek out.

also he told me that he generally sends the suspension out the door 10 out on R and 12 out on C front and rear.

I usually leave rebound stock or change according to the replacement springs. I usually will change rebound one click per .2 kg. on rear shock. If I go up on spring rate say from a 5kg to a 5.8kg , I will go in 4 clicks. That is a good place to start. After setting rebound and spring sags (and getting correct spring rate installed).

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