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Rear free sag is 1.5" do I need a stiffer spring

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Hi,

I have a 2008 CRf250x

Weight 175 without gear

I adjusted the rear spring preload to achieve 4" of rider sag.

When I check the free sag I get 1.5"

The manual says up to 1"

The spring length is still within spec, although it is close to the max ( tightest)

Do I need a new spring?

Thanks.

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Why does everyone use inches!!!!! :bonk:

Motocross is an all metric industry, unless Harley comes along and decides to build a bike! LOL :smirk:

But yea, the range you want is 40mm +/- 2 for static and 105mm +/- 5 for loaded.

If you can reach those two numbers, you'll be OK. Usually the manual will give you an optimal preload number as well, which is a measurement of the spring compressed. If the preload adjuster is almost all the way screwed in, then the spring is probably slightly too soft for ya.

For some reason, some manuals don't give the right numbers. My only guess is they are trying to be conservative and make the rear end a bit stiffer then it should be just incase you mess up riding...

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Why does everyone use inches!!!!! :bonk:

because you live in the US :smirk:

but even here in europe, water pipes and some fittings are specified in inches...

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If you get 1.5" free (static) sag and 4" race sag, and you are aiming for 1" or less free sag you would need a lighter not a heavier spring. You are most likely just fine right where you are.

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If you get 1.5" free (static) sag and 4" race sag, and you are aiming for 1" or less free sag you would need a lighter not a heavier spring. You are most likely just fine right where you are.

Thanks for the input!

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Your bike has 315mm travel both ends. Rear, You should have a static sag of 35mm (+-2mm). Rider sag of 107mm (+-2mm). 38mm is what you have now static. You will need a lighter spring. About one step. You want between 5 & 10mm preload on the spring. I am surprised you are getting 38mm of static sag and the spring is preloaded that much. Recheck your numbers including your spring free length and preloaded length. Be sure to have someone help you with measurements if you don't have a Motion Pro Uni-Sag tool.

Front you should have about 44mm static (+-2mm) and 79mm rider sag.

Hi,

I have a 2008 CRf250x

Weight 175 without gear

I adjusted the rear spring preload to achieve 4" of rider sag.

When I check the free sag I get 1.5"

The manual says up to 1"

The spring length is still within spec, although it is close to the max ( tightest)

Do I need a new spring?

Thanks.

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Your bike has 315mm travel both ends. Rear, You should have a static sag of 35mm (+-2mm). Rider sag of 107mm (+-2mm). 38mm is what you have now static. You will need a lighter spring. About one step. You want between 5 & 10mm preload on the spring. I am surprised you are getting 38mm of static sag and the spring is preloaded that much. Recheck your numbers including your spring free length and preloaded length. Be sure to have someone help you with measurements if you don't have a Motion Pro Uni-Sag tool.

Front you should have about 44mm static (+-2mm) and 79mm rider sag.

Dwight, thanks for the info. You said you are surprised about the preload being so tight with that much free sag. That is exactly what I thought and it has me wondering what could be wrong. I will recheck the sag again for the twentieth time. For the front I only had 50mm of rider sag so I dropped down from a .42 to .40 and the sag is now 60mm

I thought it would have dropped more than that. I got the springs from factory connection so I assume they are correct.

I will let you know what the measurements are after rechecking.

Thanks.

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On the front check your static sag. You may need to figure out how to put less preload on the fork spring. You are looking for about 42-46mm static. You want 77-81 rider sag. Like I said, it sounds like too much preload. The .40 sounds close if your preload is right.

Dwight, thanks for the info. You said you are surprised about the preload being so tight with that much free sag. That is exactly what I thought and it has me wondering what could be wrong. I will recheck the sag again for the twentieth time. For the front I only had 50mm of rider sag so I dropped down from a .42 to .40 and the sag is now 60mm

I thought it would have dropped more than that. I got the springs from factory connection so I assume they are correct.

I will let you know what the measurements are after rechecking.

Thanks.

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Hi,

I have a 2008 CRf250x

Weight 175 without gear

I adjusted the rear spring preload to achieve 4" of rider sag.

When I check the free sag I get 1.5"

The manual says up to 1"

The spring length is still within spec, although it is close to the max ( tightest)

Do I need a new spring?

Thanks.

No, you need a softer spring, or you're rider sag measurement is no good. I suspect the latter, since the stock spring should be pretty close for your weight (is it a stock spring?), albeit a little stiff.

You must take the measurement standing with 100% of your weight on the pegs - I like to just lightly touch the bars with my fingers while making sure I am not squeezing the bike with my legs. You'll need someone to steady the bike, and someone else to take the measurement.

JayC

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Your bike has 315mm travel both ends. Rear, You should have a static sag of 35mm (+-2mm). Rider sag of 107mm (+-2mm).

Dwight - I'm curious where you get your numbers.

The Honda factory CRF250X manual specifies a desired race sag of 100mm, and a static sag of 10mm (min) to 25mm (max). What leads you to say the bike should have 107 and 35mm respectively?

JayC

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Dwight - I'm curious where you get your numbers.

The Honda factory CRF250X manual specifies a desired race sag of 100mm, and a static sag of 10mm (min) to 25mm (max). What leads you to say the bike should have 107 and 35mm respectively?

JayC

You will find most manuals far from being correct. I got my numbers from several long time suspension gurus. I took those numbers and broke them down into percentages that can be applied to any long travel bike. If you have 12" (305mm) of travel then 100mm is correct. This bike has 315mm. You want 34% of availble travel in rider sag on a offroad bike. 33% on an MX bike. You want a static sag of 11% . On the front you want 25% of available travel in rider sag and 14% in static sag. (I am specifically talking about Offroad bikes but I think MX bikes should be close. ). You want the bike to setup for a corner and settle in (squat), front and rear. Set the sags right you have the correct springs. Control bottoming with damping. You will also notice a lower seat height with the correct springs and sags. You want less than 10mm in preload on the rear shock spring. About 5mm on front. All rider and static sags have an +- error of 2-3mm. I try to stick to 2mm. Anyone who has ridden my bikes or have followed these rules have noticed improved suspension and cornering control. KTMs with a PDS shock need slightly more static sag.

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On the front check your static sag. You may need to figure out how to put less preload on the fork spring. You are looking for about 42-46mm static. You want 77-81 rider sag. Like I said, it sounds like too much preload. The .40 sounds close if your preload is right.

Ok I rechecked the sag with gear on.

Front

38mm free sag

57mm rider sag

Rear

38mm free sag

104mm rider sag

I tried dropping the forks down 6mm to put more weight on front but that did not make a difference in the sag.

If I raise the spring Seats up 5mm is that going to only increase my sag by 5mm? 1 to 1 ratio I guess correct me if I wrong.

If I drop the oil level, will that help?

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Looks like you need to go down one step at least on fork spring.

And one step down on rear spring. Set rider sag to 107. I bet then your static sag will be about 35mm.

I think right now you will find that your rear spring is shorter than spec.

OH, I would actually raise your fork oil level 5mm. 5wt fork oil.

Ok I rechecked the sag with gear on.

Front

38mm free sag

57mm rider sag

Rear

38mm free sag

104mm rider sag

I tried dropping the forks down 6mm to put more weight on front but that did not make a difference in the sag.

If I raise the spring Seats up 5mm is that going to only increase my sag by 5mm? 1 to 1 ratio I guess correct me if I wrong.

If I drop the oil level, will that help?

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Looks like you need to go down one step at least on fork spring.

And one step down on rear spring. Set rider sag to 107. I bet then your static sag will be about 35mm.

I think right now you will find that your rear spring is shorter than spec.

OH, I would actually raise your fork oil level 5mm. 5wt fork oil.

What would raising the fork oil do?

Thanks,

Phil

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Hi,

Just set the front and rear balance (weight bias) so the bike drifts evenly in the sweepers... then set the spring rates for the most amount of weight transer that you can handle... stiffer = eaiser to ride

Who came up with the term "sag?"

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