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How do you know your FRONT forks are properly SAG'ing?

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I have an 04 yz125 and saw a thread mention checking front fork SAG. What?! I never knew!!

I have only ever just popped in springs that were for my weight per RaceTech's suspension chart.

Anyhoo, installing my .44's today for my 200lbs. Stock yz125 are .41's.

Any help on what specs should be? (ie. on the stand, static, race).

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I usually look for 3 (75mm) inches in the front end as this works well for me. You can use that setting and experiment from there.

Note that this does not really have much to do with spring rate as much as preload settings do. I dont believe people pay as much attention to fork preload/ride height since the forks can be adjusted in the clamps.

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I usually look for 3 (75mm) inches in the front end ........ I dont believe people pay as much attention to fork preload/ride height since the forks can be adjusted in the clamps.

So if you are outta whack from that 75mm sag, just get it "in whack" by triple clamp adjustments?

I thought it may have to do with like oil level in forks, clickers, or what have ya.

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Oil level only controls bottoming, not the initial part of the stroke, so it would wouldn't do anything, really. Clickers only come into play when the suspension is moving, not as you're sitting still. The only things that would matter with stock suspension would be springs and their preload...and possibly stiction, or forks that have a wheel installed incorrectly causing them to bind.

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25% is a basic static. About 30-33% for race. If your race gives you no static, you're soft. And the other way around.

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OK, so I put my .44's in today and my sag was 57mm. I guess in the ballpark, but maybe a little stiff? Going up and down my street the bike feels very nice, very balanced.

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soften up the pre load and see if you get more sag.....is that static or with you on the bike? depends on your position on the bike also.....

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soften up the pre load and see if you get more sag.....is that static or with you on the bike? depends on your position on the bike also.....

Whats the best and easiest way for him to soften preload on the forks? Shock is no problem.....forks can be.

Also, these are brand new springs that will take a set after being used a few times. Preload might be perfect then.

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here are some left out variables:

measured from on stand then sitting on bike (race sag)

bought ”used" springs from a yz250

comp all the way out (soft)

reb 5 clicks in (from soft)

didnt have gear on

sitting normal on bike

forks kinda high in triple clamp (7mm from flush)

so my gear will sag it a hair more (maybe to 60-65mm?), so getting closer to the more desired 75mm, but it seems there's not much more i CAN do eh?

note: its just fun being an anal freak about this, im not so frigging good that i will notice it, But a seriously dialed in bike can make up for skill (or getting old in my case) 👍

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Gear can add between 15-25 pounds to your weight. If you want to be real anal check it in gear with about a half to full tank of gas.

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Problem with checking rider sag on the forks is stiction. Fork seals are so large and have so much stiction that they have an effect on your measurements. This is not an issue in the rear of the bike because the swing arm has a lot of mechanical advantage over a relatively small shock seal.

I set up the front end so that there is about 1" of static sag.

The oil volume (what you're actually setting is the trapped air volume) is a secondary spring rate. It sets how progressive the front springs are. Think about it in terms of the compression ratio of an engine and it will make sense.

Oil volume doesn't have any real big effect on fork sag.

Set your sag to about 3" as others have said above. I like to have about 1" of static sag to confirm I'm in the right ballpark on my springs. A stiff spring will have a lot of static sag (more than 1-1/4") while a soft spring will have little or no static sag (less than 3/4" inch).

Then you can adjust your forks in the clamp to fine tune the chasis setup, so sag isn't as critical in the fork. You can drop them 5mm (to be flush with the clamp) or raise them 5mm (5mm gap between the line and the clamp).

Front and rear sag adjustments have an effect on eachother, so if you change one end of the chassis, re-check the other.

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