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Propper points to measure race sag?

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I am very familiar with race sag and it's effects on the bikes handling. It is critical to get the right sag for each rider. Where I get confused is the fact that most people (including me) measure vertically from the axle to the fender. Most how-to videos also show this method. When you look at a site like factory connection or look right in my rmz 250 user manual it specifically states it should be measured to the seat bolt. If you compare the results from the two methods you will see there is an 8-10 mm difference i.e. sag to fender would read 105mm and to seat bolt would be 95. To me it seems strange as the initial axle travel is actually out and then up. Factory Connection even warns not to measure vertically. There is a lot of debate on this and it seems like there should be a standard for such an important setting. It seems like Suzuki is right since they engineered the bike and obviously FC knows exactly what they are doing. I am going to test my bike set at the manufacturer recommended 105mm using both methods and see what feels right but I wanted to see if anyone has any input on this?

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I've noticed the same and it makes sense given the geometry of the measurements.  Ultimately, I think, it boils down to any suspension "recommendation" is really just a good starting point and from there you need to make adjustments.  So as long as you keep the measurements consistent, you’ll be fine.  In the end its what works for you, not what someone on some forum said.

 

You could always argue that the seat bolt location is no better, because who’s to say it’s always in the same position (in relation to the axle/shock/chassis) on different bikes.

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I agree, the only thing that makes sense about the seat bolt to me is the manufacturer says to take it there and so does FC so they are saying 105mm using the seat bolt as the reference point. Since you need a good baseline to work off I think it is important to know which method. I would lean toward the seat bolt at this point but I need to test it. Once I have a good baseline I I always try more and less preload to see what is best..

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Sag (static and race) are usually done as a percentage of total travel. Being the settings are ball park values to get you in the area you will want to be and confirm the spring rate is correct, absolute values are not what you are after. Once you set them, you ride the bike, adjust the static sag to try to maintain constant tire contact and race sag (spring rate) to prevent bottoming. So measurement points must be consistent as you compare values. Axle center and seat bolt center are convenient repeatable 'points' to use

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I understand the concept and everyone should have their own preference. If the guide says 105 at the seat bolt and you measure vertically to the fender you are actually at 95 if you measure to the bolt so you would have a bad baseline to work from correct?

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I understand the concept and everyone should have their own preference. If the guide says 105 at the seat bolt and you measure vertically to the fender you are actually at 95 if you measure to the bolt so you would have a bad baseline to work from correct?

 

Not a bad baseline, just a different one...

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If the factory calls to measure it to the bolt than it is a bad baseline to set it at 105 to the fender. You would want 115. To start where the factory tells you makes the most sense right? Those are two different measurements so it would seem to reason it does matter here the measurement is taken.

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If the factory calls to measure it to the bolt than it is a bad baseline to set it at 105 to the fender. You would want 115. To start where the factory tells you makes the most sense right? Those are two different measurements so it would seem to reason it does matter here the measurement is taken.

 

Again, it's only a starting point (as in roughly in the ballpark).  Just because the "factory" says 105 mm doesn't mean that'll work for YOU, maybe 95 or 105 or 110 mm.... will better, whatever.  Just pick a method and stick with it.

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Thanks, I guess I am not being clear. I understand different settings for different riders etc. I definitely understand sag. What I can't understand is how someone would say 105 to the fender is the right way to do it. If you want to start in the range recommended shouldn't you measure to the bolt. Otherwise they say run 105 and you are in fact running 95 because you assumed they were the same. You might like 95 but I would want to start at 105 as recommended. It just makes no sense to say either is the same. Does that make sense?

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Thanks, I guess I am not being clear. I understand different settings for different riders etc. I definitely understand sag. What I can't understand is how someone would say 105 to the fender is the right way to do it. If you want to start in the range recommended shouldn't you measure to the bolt. Otherwise they say run 105 and you are in fact running 95 because you assumed they were the same. You might like 95 but I would want to start at 105 as recommended. It just makes no sense to say either is the same. Does that make sense?

 

I understand what you’re saying... but 105 or 95 is still in the ballpark, so whether you start with 105 or 95 mm is okay.  You just might find that you need to go the opposite way in terms of adjustment to find a setting you like because you chose to a different measurement points.  Now if that difference (due to measurement locations) was great, then I would be concerned.

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I've noticed the same and it makes sense given the geometry of the measurements.  Ultimately, I think, it boils down to any suspension "recommendation" is really just a good starting point and from there you need to make adjustments.  So as long as you keep the measurements consistent, you’ll be fine.  In the end its what works for you, not what someone on some forum said.

 

You could always argue that the seat bolt location is no better, because who’s to say it’s always in the same position (in relation to the axle/shock/chassis) on different bikes.

This. In the end, you are adjusting to find the susp feel/action that works best for YOU. Too many variables for one "best" method.

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I disagree, you want to start at a good point and saying that starting point is irrelevant just makes no sense. Sure everyone should have their own setting but why start way off the mark? It actually makes sense if you look at the full travel of the rear axle. If you draw an arc from the rear axle with the swingarm axle as the pivot point it goes pretty much right to the seat bolt. The majority of the travel is at a forward angle and not vertical. I set mine to 105mm to the seat bolt which is 115mm if measured vertically. This is what both Suzuki and Factory Connection recommend. The bike is totally different and exits turns like I have never experienced. Overall it feels way better set this way. Now I can find what works on either side of that but it would be ridiculous to start at some arbitrary number when the manufacturer states clearly to measure to the seat bolt. I am sold- measure according to the factory recommendation or your suspension tuner's recommendation. Don't just measure vertically unless they specifically say to do it that way. It is one of those RTFM moments and I have been doing it wrong for a year:-o  

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I disagree, you want to start at a good point and saying that starting point is irrelevant just makes no sense. Sure everyone should have their own setting but why start way off the mark? It actually makes sense if you look at the full travel of the rear axle. If you draw an arc from the rear axle with the swingarm axle as the pivot point it goes pretty much right to the seat bolt. The majority of the travel is at a forward angle and not vertical. I set mine to 105mm to the seat bolt which is 115mm if measured vertically. This is what both Suzuki and Factory Connection recommend. The bike is totally different and exits turns like I have never experienced. Overall it feels way better set this way. Now I can find what works on either side of that but it would be ridiculous to start at some arbitrary number when the manufacturer states clearly to measure to the seat bolt. I am sold- measure according to the factory recommendation or your suspension tuner's recommendation. Don't just measure vertically unless they specifically say to do it that way. It is one of those RTFM moments and I have been doing it wrong for a year:-o  

You are absolutely, totally correct. But! The exact same improvement in suspension action could be achieved by altering the preload measurement at ANY measurement point, vertical or arc. A 100mm measurement will be far different if measured by the arc method. If a 100mm rider sag is recommended but I feel 105 is better, then the difference in action comes from the preload measurement, not where I chose to measure. I am saying that it is "best" to choose and CONSISTENTLY use a single method to measure for accuracy.  I think both methods can be used to achieve the same suspension action.

Edited by YHGEORGE

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You are absolutely, totally correct. But! The exact same improvement in suspension action could be achieved by altering the preload measurement at ANY measurement point, vertical or arc. A 100mm measurement will be far different if measured by the arc method. If a 100mm rider sag is recommended but I feel 105 is better, then the difference in action comes from the preload measurement, not where I chose to measure. I am saying that it is "best" to choose and CONSISTENTLY use a single method to measure for accuracy.  I think both methods can be used to achieve the same suspension action.

Thanks for the input!

I agree but why would you just start at some random number when you can start where they actually recommend. Sure, I could take it at the fender at 115mm now that I know that measurement but for an inexperienced rider they will set it at 105 to the fender and leave it never realizing they are at 95. Set it where the manufacturer or suspension tuner says to set it then you can see what that measurement is to a more convenient location and use that number. Don't use 105 and measure wherever you want to because you will not be at 105 according to the manufacturer;-)Otherwise you have no good baseline.

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Thanks for the input!

I agree but why would you just start at some random number when you can start where they actually recommend. Sure, I could take it at the fender at 115mm now that I know that measurement but for an inexperienced rider they will set it at 105 to the fender and leave it never realizing they are at 95. Set it where the manufacturer or suspension tuner says to set it then you can see what that measurement is to a more convenient location and use that number. Don't use 105 and measure wherever you want to because you will not be at 105 according to the manufacturer;-)Otherwise you have no good baseline.

You are missing the concept. That's ok, it will all work out.

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You are missing the concept. That's ok, it will all work out.

 

You can lead a horse to water, but.... either way it worked out for the OP  :thumbsup:

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No, you are missing the concept. If the factory says 105 to the seat bolt why would I measure somewhere else? Sorry, but that makes no sense.

105 to the seat, 95-100 to the fender, whatever floats your boat.

 

they're basic/rough ideas of where to start. if you care much at all about your suspension and how it works you'll likely end up tweaking it many times and eventually come up with what works for you.

 

the main issue with putting too much importance into the factory values is that they take nothing into consideration concerning terrain or skill. those 2 variables make the biggest difference in the race sag setting bar none.

 

so like everyone else has said; just pick a method and stick with it. once you work it out on a bike or 2 you'll be able to do it for others in a snap.

 

.

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I give up. I understand sag and I understand you should set it what works best for you. That is just obvious. Go ahead and measure 105 to the fender when the factory says 105 to the bolt and wonder why your bike is too busy. I also know this is a starting point but you should at least start at the right sag. It is critical to setup so I can't see why everyone is - "just measure wherever, it doesn't matter". It does if you are always 10mm off on your measurement because you are stubborn. I don't think any of that is good advice. I am out on this ridiculous conversation.

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