Adjusting the FJR's suspension.......

[SkooterG]

Had a little suspension adjustment party today with mi bastard step-pappy. We played with my (new to me) 09 FJR with 3300 miles, and his 2003 FJR with 60k miles. Both have completely stock suspensions.

I used the Racetech/Lee Parks method in all cases.

For SAG, we went looking for 28-33% of total suspension travel. For the FJR's front 5.3 inches (or 135mm) of total travel, the desired range was 38-46mm, or at 30%, 41mm. For the rear's 4.9 in (or 125mm) of travel, the desired range is 35-41mm, or 38mm.

First up was mi bastard step-pappy beemerdons' FJR. At 10 years old, with 60k miles, and his uhhhhh..... *portly* figure riding it, I figured it could use all the help it could get so I dialed in max preload for the front forks. He was at three lines, I dialed in to one. With him on the bike, SAG measured 39.5mm. I was impressed that we were even able to get in the correct range. I backed it out just a smidge to get closer to 41mm and didn't bother re-measuring.

For his rear, well, the results weren't so good. With the lever in the 'hard' setting, his rear had 57mm of SAG. WELL over the ideal of 38mm. Nothing to adjust there. As I have been telling the lout for years, he really needs a new shock. It is way undersprung for just him, and I have seen him carry some non-waif passengers if you know what I mean.

Adjusted front rebound. I got where I wanted but it was with max rebound dialed in - only one click out. Would have liked to try a bit more, but obviously couldn't. His forks have never been serviced.

Adjusted rear rebound acceptably too, but funny on his stock shock, after about 8 clicks the 'clicks' just went away! So I have no idea where it's at. But it seems ok.

TIME TO GET AN AFTERMARKET SHOCK EL PENDEJO GRANDE!!! There, that's only about the 100th time I have told him that.

Next on to my 09 FJR.

My first measurement for front SAG was 52mm. Well over the ideal of 41. With max preload dialed in (one line), I still only got 45mm. Barely in the right range. I still need more preload. For the life of me, I can't understand why we were able to get beemerdons 03 FJR with his rotundness dialed in perfectly, and not mine with my considerably lighter frame. I may have to double-check and measure this again to make sure I get the same thing.

For the rear, in the 'soft' setting I got 32.5mm of SAG! WELL below the desired range of 35-41mm or the ideal setting of 38mm. So for years everybody has been complaining how even the Gen II shock is undersprung (they increased spring rates from Gen I) but for me, it is OVER sprung. No doubt contributing to some of the harshness I have been feeling riding this new to me Gen II that I can't seem to get totally rid of. Also interesting, in the 'hard' setting the SAG measured at 31.5mm. Only 1 mm different than the 'soft' setting. Not much difference at all! BTW - I am 180lbs buck naked, so figure 200lbs or so with gear.

I then adjusted my rear, or shock rebound damping. Whatever I did to it DID seem to help with the harshness though I still need to take it out on some of the crappier roads I regularly ride before I make any conclusions.

Though I have played with my own Gen I custom suspensions before, this was the first time I played with a couple of stock suspensions. I find the results interesting.

 

[CAJW]

Had a little party today with mi bastard step-pappy.

For his rear, well, the results weren't so good. With the lever in the 'hard' setting, his rear had 57mm of SAG. I find the results interesting.

Amazing what you get when you read between the lines. Probably should've been labeled NWS!

Me thinks Odot is rubbing off on me.

 

[RedPorscheKilla]

[quote name='SkooterG' timestamp='1351652452' post='

I then adjusted my rear, or shock rebound damping. Whatever I did to it DID seem to help with the harshness though I still need to take it out on some of the crappier roads I regularly ride before I make any conclusions.

SkooterG,

As much as I love my 07 FJR, dialing the rear shock in to hard was the big, WTF nothing happened moment with her. I'm used to my Suzi's and harder dial on preload, being not the smallest fella myself.

Well my remedy is on my farkle list, Upgraded suspension, front and rear......

Speaking of which, what do you think of longer bones? I found on da bay a set which would lift her about an inch, worth doing in conjunction with a Penske/Oehlins shock?

Thx a lot

RPK (V)

 

[TomInPA]

When Barry rode Don's bike to the Ruben RTE, he described some poor handling problems. I noticed the fork preload was fully out at 3-rings and offered to make an adjustment when we were at FJRay's. Barry declined on the basis it was a borrowed bike, but I knew it wasn't giving anywhere near maximum performance. The rear shock is still dry so at least it hasn't been blown by the miles and loads. I rebuilt my forks at about 24K miles and it made a lot of difference, but like Don, I could really use a rebuilt or aftermarket main shock. I'm kind of looking at the Sasquatch rebuild.

 

[MCRIDER007]

As you said, the fork results are not what one would expect but there could be an explanation. I don't how you measured sag but you could get some misleading results depending on the amount of stiction in the forks or because of a difference of weight on the front end due to differences in sag at the back end. If Don's bike has 57 mm of sag and you only have 31 mm, that is going to impact both the steering geometry and the weight on the front end. If you re-measure the fork sag, try comparing how much tube is showing between the dust caps and the triple clamp to verify he actually has less sag than you do.

I think your desired sag in the rear is on the high side but every suspension guru seems to have a different idea of what is ideal, the only thing that really counts is the relationship between the front end and the back end the rider determines what steering geometry he likes the best. I suspect your harsh ride from the shock is due to too much compression damping, the damping adjustment actually changes both compression and rebound damping so if you are getting a harsh ride you need to reduce the damping as far as you can without losing your desired rebound damping. My experience is that the damping is designed for the soft setting, you can get a pretty plush ride and still have adequate rebound damping; the hard setting is quite different, it is always going to be a harsh ride with the correct rebound damping.

 

[yamafitter]

At 60K miles the fork oil has probably completely broken down in BeemerDons' FJR. Step #1 is to pull the forks apart and replace all the bushings and seals and get some fresh oil in there. After doing that I strongly suspect that you will find that there will be a difference in the sag settings. I did not see any mention of the free sag readings. If the sag with the rider on board is correct but the free sag is too small or non existent then the fork springs are too weak for the load they are being asked to carry. Measuring free sag is also a very good way to tell how much stiction there is in the forks. The proper way to measure free sag is to first measure the forks fully extended with no weight on the front wheel. Next with no rider on the bike and the bike on its wheels and someone holding it so it doesn't fall over, gently raise the front end and allow it to gently settle to its resting point. Measure the fork length. Next gently push down and allow the bike to return to the resting point without bouncing. Take a second measurement. If there is a difference of more than 10mm between the two measurements than there is too much stiction in the forks and you should consider corrective action. The final free sag number is the average of the two free sag measurements subtracted from the fully extended measurement and ideally should be between 20-30 mm.

The first step in a good suspension setup is to match the spring rate to the load since it is the springs that set the static ride height that affects geometry. If you have so much pre-load dialed in that here is no free sag the bike suspension will be harsh over small undulations since the suspension will not react. If the suspension is not moving no amount of playing with the clickers is going to fix it.

Adjusted front rebound. I got where I wanted but it was with max rebound dialed in - only one click out. Would have liked to try a bit more, but obviously couldn't. His forks have never been serviced.Adjusted rear rebound acceptably too, but funny on his stock shock, after about 8 clicks the 'clicks' just went away! So I have no idea where it's at. But it seems ok.

This is just scary. Are you sure someone didn't use tap water for fork oil. When you take the rear shock off, beat Don with the shock for letting things get this bad.

 

[SkooterG]

SkooterG,

As much as I love my 07 FJR, dialing the rear shock in to hard was the big, WTF nothing happened moment with her. I'm used to my Suzi's and harder dial on preload, being not the smallest fella myself.

Well my remedy is on my farkle list, Upgraded suspension, front and rear......

Speaking of which, what do you think of longer bones? I found on da bay a set which would lift her about an inch, worth doing in conjunction with a Penske/Oehlins shock?

The FJR's lever is not like a traditional preload. It actually changes spring rate by locking out a secondary spring. What that means in the great scheme of things I have no idea, but I was very surprised at how little it meant in the static sag. Both aftermarket shocks I have run have raised the ride height. They did this without purposely adding ride height in, so I assume it was just a higher spring rate. So for me, there was no need at all for longer bones to change ride height. I would definitely get the custom shock first, and see how it works, and then go from there.

When Barry rode Don's bike to the Ruben RTE, he described some poor handling problems. I noticed the fork preload was fully out at 3-rings and offered to make an adjustment when we were at FJRay's. Barry declined on the basis it was a borrowed bike, but I knew it wasn't giving anywhere near maximum performance. The rear shock is still dry so at least it hasn't been blown by the miles and loads. I rebuilt my forks at about 24K miles and it made a lot of difference, but like Don, I could really use a rebuilt or aftermarket main shock. I'm kind of looking at the Sasquatch rebuild.

Actually, fully out for the fork preload is 5 lines. At 3 lines, his was set in the middle the way it comes from the factory. Yes, no doubt you need to do something with your shock. The Sasquatch is not a bad option, but imho, aftermarket is the way to go. Stock shock gives no separate compression and rebound damping adjustment and I really like the remote preload adjusters of aftermarket shocks. Best is to snag a $1100-$1200 shock used for $450-$600!

As you said, the fork results are not what one would expect but there could be an explanation. I don't how you measured sag but you could get some misleading results depending on the amount of stiction in the forks or because of a difference of weight on the front end due to differences in sag at the back end. If Don's bike has 57 mm of sag and you only have 31 mm, that is going to impact both the steering geometry and the weight on the front end. If you re-measure the fork sag, try comparing how much tube is showing between the dust caps and the triple clamp to verify he actually has less sag than you do.

I think your desired sag in the rear is on the high side but every suspension guru seems to have a different idea of what is ideal, the only thing that really counts is the relationship between the front end and the back end the rider determines what steering geometry he likes the best. I suspect your harsh ride from the shock is due to too much compression damping, the damping adjustment actually changes both compression and rebound damping so if you are getting a harsh ride you need to reduce the damping as far as you can without losing your desired rebound damping. My experience is that the damping is designed for the soft setting, you can get a pretty plush ride and still have adequate rebound damping; the hard setting is quite different, it is always going to be a harsh ride with the correct rebound damping.

I was hoping you would post. You are very knowledgeable on the subject and I was hoping for your input. I did take the three measurements to account for stiction. I also measured the forks in the manner you describe.

Here are the actual measurements:

Don's 03: L1=139.5mm, L2=111.5mm, L3=89mm. So he had 22.5mm of stiction. I have been told that is not necessarily excessive. But obviously his forks need to be serviced.

My 09: L1=148mm, L2=100mm, L3=92mm. Only 8mm of stiction. And I just realized - why are my and Don's L1 so far off? Something wrong there as they were measured in the same way using the same locations. I am going to have to redo some of this. I wonder if my L1 should actually be 138mm???

I was thinking yesterday that I wonder if it was a mistake setting Don's front sag correctly when his rear sag is so out of whack. I added to the rear down, front up attitude. Now Don is not an aggressive rider, but I imagine it's not helping his handling at all to be so uneven in front to rear sag.

I didn't know that the bottom shock adjustment controlled both compression and rebound. Where did you get that? I thought there was no compression damping. I believe yesterday when I adjusted mine I ended up taking some damping out. It has definitely helped the harshness though I still need to ride it more. And harshness is still there. I have been spoiled by the custom suspension on my 04 FJR. I've got it dialed in nicely and get a plush ride and excellent handling. No $$$$ so no custom suspension on the 09 anytime soon so I am stuck with what I got. Oh, and even before measuring, after playing a little bit, I keep my lever in the 'soft' setting with just me riding the bike. Yesterday I had to give a friend a short ride two-up. He's got to weigh 200ish. With the lever in 'hard' I felt the FJR sag quite a bit when he got on. But the ride quality was very plush.

At 60K miles the fork oil has probably completely broken down in BeemerDons' FJR. Step #1 is to pull the forks apart and replace all the bushings and seals and get some fresh oil in there. After doing that I strongly suspect that you will find that there will be a difference in the sag settings. I did not see any mention of the free sag readings. If the sag with the rider on board is correct but the free sag is too small or non existent then the fork springs are too weak for the load they are being asked to carry. Measuring free sag is also a very good way to tell how much stiction there is in the forks. The proper way to measure free sag is to first measure the forks fully extended with no weight on the front wheel. Next with no rider on the bike and the bike on its wheels and someone holding it so it doesn't fall over, gently raise the front end and allow it to gently settle to its resting point. Measure the fork length. Next gently push down and allow the bike to return to the resting point without bouncing. Take a second measurement. If there is a difference of more than 10mm between the two measurements than there is too much stiction in the forks and you should consider corrective action. The final free sag number is the average of the two free sag measurements subtracted from the fully extended measurement and ideally should be between 20-30 mm.

The first step in a good suspension setup is to match the spring rate to the load since it is the springs that set the static ride height that affects geometry. If you have so much pre-load dialed in that here is no free sag the bike suspension will be harsh over small undulations since the suspension will not react. If the suspension is not moving no amount of playing with the clickers is going to fix it.

Adjusted front rebound. I got where I wanted but it was with max rebound dialed in - only one click out. Would have liked to try a bit more, but obviously couldn't. His forks have never been serviced.Adjusted rear rebound acceptably too, but funny on his stock shock, after about 8 clicks the 'clicks' just went away! So I have no idea where it's at. But it seems ok.

This is just scary. Are you sure someone didn't use tap water for fork oil. When you take the rear shock off, beat Don with the shock for letting things get this bad.

Yes, Don needs to get his forks serviced. I told him that. I think I finally convinced him to do some upgrading too. I'm not too good about servicing forks either. I once went 92k miles between servicing, and on my 04 with the Traxxion AK-20s, they are currently at about 80,000 miles. I have been meaning to get to it for quite some time ...........

While I understand what you are saying about Free Sag I am not sure if I buy into if it's an important measurement or not. Now all my suspension knowledge is for the most part from Lee Parks (and therefore also RaceTech) training and he doesn't use Free Sag. I guess to my thinking it's like who cares about Free Sag when all that REALLY matters is the static sag measurements with the rider on the bike being important. Right? I did take into account stiction as I went into above, but I have been told that 20-30mm of stiction in forks is not necessarily unreasonable though obviously not desireable.

And as for mi bastard step-pappy, it's like preaching to a wall. Do you know how many times I have provided him a link to a great deal on a used custom shock and urged, no.... PLEADED for him to buy it only for him to get that stupid shit eating grin he has? Aye Carumba!

 

[wheatonFJR]

Had a little party today with mi bastard step-pappy.

For his rear, well, the results weren't so good. With the lever in the 'hard' setting, his rear had 57mm of SAG. I find the results interesting.

Amazing what you get when you read between the lines. Probably should've been labeled NWS!

Me thinks Odot is rubbing off on me.

That right there is not worksafe...please refrain. :lol:

 

[SkooterG]

Had a little party today with mi bastard step-pappy.

For his rear, well, the results weren't so good. With the lever in the 'hard' setting, his rear had 57mm of SAG. I find the results interesting.

Amazing what you get when you read between the lines. Probably should've been labeled NWS!

Me thinks Odot is rubbing off on me.

That right there is not worksafe...please refrain. :lol:

:rofl: :rofl: :rofl:

Swing and HOME RUN by Wheatie! Can't believe I missed that softball myself.

 

[Bustanut joker]

Odot rubs off on everybody.. Some strange Eskimo ritual or sumpin... :blink:

As far as Don's bike.. I'm no speed racer, those days are passed. Self preservation mode kicked in years ago when I woke up with an unexpected zipper in me chest.

After being spoiled by the upgrades to my fat pig I'd forgotten what a good thing a half pocketfull of $ can do.

That being said the gurl has been road hard an put away wet a few too many times. :lol: You'd think A high quality gal like that a man would respect and treat her kindly...60K and still swimming in the same bathwater???

I think you should put her in touch with a divorce lawyer Scoot.. Or at least get her an Don into counseling.

 

[MCRIDER007]

Here are the actual measurements:

Don's 03: L1=139.5mm, L2=111.5mm, L3=89mm. So he had 22.5mm of stiction. I have been told that is not necessarily excessive. But obviously his forks need to be serviced.

My 09: L1=148mm, L2=100mm, L3=92mm. Only 8mm of stiction. And I just realized - why are my and Don's L1 so far off? Something wrong there as they were measured in the same way using the same locations. I am going to have to redo some of this. I wonder if my L1 should actually be 138mm???

I was thinking yesterday that I wonder if it was a mistake setting Don's front sag correctly when his rear sag is so out of whack. I added to the rear down, front up attitude. Now Don is not an aggressive rider, but I imagine it's not helping his handling at all to be so uneven in front to rear sag.

I didn't know that the bottom shock adjustment controlled both compression and rebound. Where did you get that? I thought there was no compression damping. I believe yesterday when I adjusted mine I ended up taking some damping out. It has definitely helped the harshness though I still need to ride it more. And harshness is still there. I have been spoiled by the custom suspension on my 04 FJR. I've got it dialed in nicely and get a plush ride and excellent handling. No $$$$ so no custom suspension on the 09 anytime soon so I am stuck with what I got. Oh, and even before measuring, after playing a little bit, I keep my lever in the 'soft' setting with just me riding the bike. Yesterday I had to give a friend a short ride two-up. He's got to weigh 200ish. With the lever in 'hard' I felt the FJR sag quite a bit when he got on. But the ride quality was very plush.

You are going to have to explain your L1, L2, L3 measurements to make sure we are on the same page but I think sag is way overrated. Sag is very useful for determining if you have the right springs but pretty useless on the forks for setting your suspension. Why? You can't change the sag unless you preload the main spring and the adjusters on the forks do not preload the main spring, they actually compress the top out springs that are on the cartridge. This increases the length of the forks making it appear that the sag changes but it actually stays the same, you are just measuring from a different point. The bottom line is that the adjusters change the ride height and the steering geometry...not the actual sag. I would say that your numbers look pretty accurate for the OEM springs and they are a bit under sprung.

The OEM shock is a standard emulsion shock (oil mixed with nitrogen) and contains a double shim stack. Oil passes through the shock's shim stacks in both directions giving both compression and rebound damping and the adjuster limits the oil flow to a common valve. The shock has to have both compression and rebound damping and this is probably the lowest cost way to build it. I think they choose to call it a rebound damping adjustment because the rebound damping is the most important and that what you should strive to get right. When you change the damping you are probably changing the rebound more than the compression but that would depend on the design of the shim stacks...but the change is always in the same direction and that is the problem because your compression and rebound damping needs are going to change (usually in opposite directions) depending on spring weight, load, speed, and road surface. If you go to a heavier spring on a balanced system then you need more rebound damping but less compression damping. There is about a 200 pound spring difference between the FJR's soft and hard settings and its not possible to be able to have the correct damping settings for both spring sizes unless you have individual adjustments although an ideal setting for a solo rider on the soft setting may not be that bad for riding double on the hard setting.

I think you should try to find a good damping setting for a plush ride on the soft setting and then adjust your ride height on the forks to give you a neutral steering geometry for long distance riding...don't worry about the sag unless you feel that you are bottoming under heavy braking. When you get to the twisties and want to greatly increase the pace, go to the shock's hard setting. This will give you more ground clearance and quicker steering, the ride will be harsher but you probably won't notice when you are on the verge of dragging the pegs.

 

[beemerdons]

And as for mi bastard step-pappy, it's like preaching to a wall. Do you know how many times I have provided him a link to a great deal on a used custom shock and urged, no.... PLEADED for him to buy it only for him to get that stupid shit eating grin he has? Aye Carumba!

What stupid shit eating grin, eh? Oh, did you mean this one? Thanks everyone for your advice and huge thanks to you SkooterG, Si Hombres I promise to upgrade my forks and buy an aftermarket shock before I leave for Cabo San Lucas in January. Verdad!

 

[SkooterG]

You are going to have to explain your L1, L2, L3 measurements to make sure we are on the same page but I think sag is way overrated. Sag is very useful for determining if you have the right springs but pretty useless on the forks for setting your suspension. Why? You can't change the sag unless you preload the main spring and the adjusters on the forks do not preload the main spring, they actually compress the top out springs that are on the cartridge. This increases the length of the forks making it appear that the sag changes but it actually stays the same, you are just measuring from a different point. The bottom line is that the adjusters change the ride height and the steering geometry...not the actual sag. I would say that your numbers look pretty accurate for the OEM springs and they are a bit under sprung.

The OEM shock is a standard emulsion shock (oil mixed with nitrogen) and contains a double shim stack. Oil passes through the shock's shim stacks in both directions giving both compression and rebound damping and the adjuster limits the oil flow to a common valve. The shock has to have both compression and rebound damping and this is probably the lowest cost way to build it. I think they choose to call it a rebound damping adjustment because the rebound damping is the most important and that what you should strive to get right. When you change the damping you are probably changing the rebound more than the compression but that would depend on the design of the shim stacks...but the change is always in the same direction and that is the problem because your compression and rebound damping needs are going to change (usually in opposite directions) depending on spring weight, load, speed, and road surface. If you go to a heavier spring on a balanced system then you need more rebound damping but less compression damping. There is about a 200 pound spring difference between the FJR's soft and hard settings and its not possible to be able to have the correct damping settings for both spring sizes unless you have individual adjustments although an ideal setting for a solo rider on the soft setting may not be that bad for riding double on the hard setting.

I think you should try to find a good damping setting for a plush ride on the soft setting and then adjust your ride height on the forks to give you a neutral steering geometry for long distance riding...don't worry about the sag unless you feel that you are bottoming under heavy braking. When you get to the twisties and want to greatly increase the pace, go to the shock's hard setting. This will give you more ground clearance and quicker steering, the ride will be harsher but you probably won't notice when you are on the verge of dragging the pegs.

Sorry, I should have clarified. For the forks, measurements were from bottom of lower triple clamp to top of dust seal. L1 = Suspension Free Length, or suspension fully extended (wheel off ground). L2 = Rider mounted, assistant steadying bike, and suspension lifted, then slowly let down. L3 = Rider mounted, assistant steadying bike, and suspension pushed down, then slowly let up.

Interesting - I just remeasured my 09's L1 for the forks again and it is indeed 148mm. For comparison, I measured my 04's L1 and it is only 128mm. These forks do have the Traxxion AK-20s. But obviously some differences here between Gen I and Gen II.

As for the forks, I followed most of what you said. Not so much this: (I think I need a diagram )

they actually compress the top out springs that are on the cartridge. This increases the length of the forks making it appear that the sag changes but it actually stays the same, you are just measuring from a different point.

I think sag is important in that you want to have travel for both compression and extension. And no matter what the method is, if you are adjusting how much the bikes sags with rider on board, then you are adjusting sag. You might not be preloading the fork springs in the conventional manner, but if static sag (rider onboard) is altered, the it's working. Right?

Thanks for the explanation of the shock and the double adjusting of the shim stack. I was unaware. So do you have any idea if when Sasquatch rebuilds the stock shock, does he change that at all? Or is it the same. Because that to me would be a major limitation vs. going aftermarket. I agree rebound damping adjustment is much more critical than compression, and that going to a heavier spring really exacerbates that.

I like your advice except for the hard setting for the twisties. While you are right that if I am riding aggressively I am really not too concerned with a harsh ride but I would be concerned with the suspension getting upset going over bumps while leaned over. I'll have to do some experimenting.

Thanks for your help. Suspension stuff is newer to me. I have much to learn and I am determined to figure it out as best I can

 

[MCRIDER007]

Sorry, I should have clarified. For the forks, measurements were from bottom of lower triple clamp to top of dust seal. L1 = Suspension Free Length, or suspension fully extended (wheel off ground). L2 = Rider mounted, assistant steadying bike, and suspension lifted, then slowly let down. L3 = Rider mounted, assistant steadying bike, and suspension pushed down, then slowly let up.

Interesting - I just remeasured my 09's L1 for the forks again and it is indeed 148mm. For comparison, I measured my 04's L1 and it is only 128mm. These forks do have the Traxxion AK-20s. But obviously some differences here between Gen I and Gen II.

As for the forks, I followed most of what you said. Not so much this: (I think I need a diagram )

they actually compress the top out springs that are on the cartridge. This increases the length of the forks making it appear that the sag changes but it actually stays the same, you are just measuring from a different point.

I think sag is important in that you want to have travel for both compression and extension. And no matter what the method is, if you are adjusting how much the bikes sags with rider on board, then you are adjusting sag. You might not be preloading the fork springs in the conventional manner, but if static sag (rider onboard) is altered, the it's working. Right?

Thanks for the explanation of the shock and the double adjusting of the shim stack. I was unaware. So do you have any idea if when Sasquatch rebuilds the stock shock, does he change that at all? Or is it the same. Because that to me would be a major limitation vs. going aftermarket. I agree rebound damping adjustment is much more critical than compression, and that going to a heavier spring really exacerbates that.

I like your advice except for the hard setting for the twisties. While you are right that if I am riding aggressively I am really not too concerned with a harsh ride but I would be concerned with the suspension getting upset going over bumps while leaned over. I'll have to do some experimenting.

If you look at a picture of an FJR cartridge you see a small spring about halfway from the bottom. This is the top out spring and what the bottom of the tube makes contact with when it is extended. When you screw in the adjusters you are putting pressure on the main spring but you are also lifting the cap and tube it is attached to. The weaker spring is the one that is going to compress and that is the top out spring. As the bottom of the tube compresses the top out spring the tube gets longer. If the main spring is not compressed by the adjusters, then it is going to compress the same amount (sag) when weight is applied regardless if the adjusters are full end or full out. Try taking your L1 measurement with both adjusters full in and full out, I think you will see about 10-12 mm difference.

I transferred the entire cartridge (with its GP Suspension components) from my 05 to my 08 and the only difference in the fork tube that I could see was the the 08 had a larger hole in the bottom so you could extract the oil cup with the tube in place. The cartridge sits in the tube and can be removed without removing the tube. When you installed the Traxxion AK-20s you changed the entire cartridge, which may have have had longer top out springs, the main springs...which were probably a different length, and spacers. Any one of those changes could change your L1 measurement.

Sag is important for the reasons you stated, but my point was that when top out springs are involved, you probably are not preloading the main spring and sag is actually fixed....the only way to change sag is to change the springs. You should be concentrating on getting your damping and steering geometry correct.

My comments about switching between soft and hard in the twisties is based on experience. Higher speeds require more spring to avoid excessive loading and bottoming, and I found the hard setting was a lot more stable both on smooth pavement and bumps...but I'm heavier than you. Try it and decide which you like the best.

I'm going to send you a PM regarding the other question you asked.

 

[Fred W]

There's a really easy way to measure your sag on the forks. Just zip a ty-wrap somewhat loosely around the stanchion (stationary) tube on one of the two legs and push it down to the dust cap. Then load the bike up gently. The ty-wrap will slide up the stanchion tube as far as the slider pushes it up. Again, gently unload the bike, set it up on the center stand without bouncing the forks, and measure the distance between the top of the dust cap and the ty-wrap. That is your dynamic sag. If you want to measure those stiction differences you'll need to have an assistant to push the ty-wrap down after you do your compress and release move.

I find the differences that you measured and attribute to stiction to be fairly appalling. I'm not sure if it was a measurement error or a misunderstanding of what you said on my part, but if there was that much difference on my forks I'd be really really worried.

I also agree with MCRider's assertion that setting up the sag is very over-rated. I think that stems from the fact that it is really easy to measure and do, more than the fact that it makes a huge difference in suspension compliance. All you really want to accomplish is to have the suspension operating in (roughly) the middle part of it's operating range as you go down the road, so you don't bottom out on big hits nor top out on big drop-offs. And secondarily, to have the suspension geometry (steering angles) in a good place.

We always talk about steering stability issues, it's a common complaint in the NEPRT section (wobbles, quickness of turn in, etc.) and steerring angles has a big influence on steering stability and responsiveness.

One thing that is sometimes overlooked in the whole sag setup is that the air space over the oil level acts as a supplementary, progressive spring. You could adjust that level somewhat to fine tune the spring rate. Most of us just set it to spec and forget it, which is fine. Just remember to check it before you fiddle with sag, 'cause it will effect it if you change the level later. Either way, because this supplementary "air spring" is progressively increasing as the fork is compressed (and decreasing when it is extended) don't be afraid to set your dynamic sag a little larger than the oft quoted 1/3 of total stroke. If you start taking hits that bottom the fork, you'll know it really quick, and can up the pre-load to avoid that.

 

[RadioHowie]

Considering the topic of this thread, and the participants currently involved, i.e., SkooterG, FredW and MCRIDER007...even BeemerDons, since he and I are both "hefty bags", plus my 04 is swiftly approaching 75k miles and the front and rear suspension $$$ bits are still stock, I wanted to jump in and ask a question or three.

First of all, a quote from Skoot's 4th post, #13 in the thread, he says

I think sag is important in that you want to have travel for both compression and extension. And no matter what the method is, if you are adjusting how much the bikes sags with rider on board, then you are adjusting sag. You might not be preloading the fork springs in the conventional manner, but if static sag (rider onboard) is altered, then it's working. Right?

...and this confuses me. I've been to several different web sites and keep getting different definitions of what static and dynamic sag are. Some say static sag is the amount of spring sag of JUST the bike while others define dynamic sag as the amount of JUST the bike, and Skooter's post above states the same thing (rider onboard). This is confusing the hell out of me.

It would make sense that STATIC sag is the measurement of the bike all by itself, as in a weight that is static, or in other words (other than weight of fuel) doesn't change. The bike ALWAYS weighs the same, so the weight is static, therefore the sag measurement is static. Whereas dynamic, meaning (to me) changeable, variable, as in the sag would be dynamic depending on the weight of the rider(s), gear and luggage.

So, based on MY understandings of the two different terms, the STATIC sag is the measurement of spring compression and how it is affected ONLY by the weight of the motorcycle, while DYNAMIC sag is the measurement affected by rider, passenger and gear.

Now, again based on MY definitions, STATIC sag seems to be the only adjustable sag in the discussion. Measure the unloaded extension of the suspension, lower the bike on its wheels and measure again. The difference is the STATIC sag, right??? And you adjust the difference on the forks up or down with the pre-load adjusters. The rear shock isn't really "adjustable" in the way the forks are, with the "soft/hard" settings being the only adjustment to spring force, hence the popularity of aftermarket suspension parts for the FJR.

I say that STATIC sag is the only adjustable setting, since based on MY understanding that DYNAMIC sag is affected only by the rider(s) weight and luggage, if one were to use the adjusters on the fork to set DYNAMIC sag, you've effectively screwed up the STATIC sage, so the only way to compensate is with fork and shock springs with weaker or stronger spring forces.

So, assuming, again based on MY understanding, if you set the STATIC sag to optimal, then find the DYNAMIC sag is off the "accepted" 1/3 total travel, the only way to achieve optimal DYNAMIC sag is to change the springs to match the weight of the rider(s) and luggage.

Is MY understanding correct, or am I 180 degrees off base? (For a change) I'm serious here, as, stated previously, my bike is aging and I'm sure when I measure my STATIC and DYNAMIC sags, I'm gonna be WAY disappointed with my readings, due to spring sack and FRS.

And, for a final question, WHY is STATIC sag important at all? It would seem to me that what matters for optimal performance from the suspension, is that DYNAMIC sag is correct. So why even bother with setting STATIC sag???

Whew...hope I haven't asked TOO MUCH STUFF!!!

'Howie

 

[MCRIDER007]

And, for a final question, WHY is STATIC sag important at all? It would seem to me that what matters for optimal performance from the suspension, is that DYNAMIC sag is correct. So why even bother with setting STATIC sag???

An ideal spring rate would be one that had a linear compression rate leading to the desired dynamic sag. In other words, if the bike's weight on the spring and the rider's weight were the same, the static sag would be half the dynamic sag. What you want to avoid is a situation where it takes so much preload to achieve the desired dynamic sag that the static sag and dynamic sag are almost the same. If that were to happen, you would not have the ability to have enough negative travel....which actually happens quite a bit (high speeds creates negative travel because the bike gets lighter). This situation is not going to happen on the forks but could happen on a shock that has a very weak spring.

While you change the static sag to get to the desired dynamic sag, the relative difference between the two sags is an indication of how close you are to the correct spring rate.

It should also be noted that while a "heavy spring" or preloaded "light spring" may give the same dynamic sag, the heavier spring will give a softer ride when in negative travel and more resistance to bottoming under heavy braking.

 

[Fred W]

First off, static sag is without the rider and other load (just the bike). Dynamic is the whole load.

My take on this is that static sag is not important in the least. The suspension will never see a time when the bike is riding down the road without the full load, so the only sag that is significant is the dynamic one. The use of multiple (static and dynamic) sag measurements is an attempt to pick a spring rate that is strong enough to support the load of the bike and rider and still allow full articulation of the suspension over the nominal road irregularities that are expected. The problem for street risers is that what is nominal in one area (let's say down south for example) may be a lot smoother than up north where the winter freeze thaw cycles rip the crap out of the road surfaces.

In other words, selecting the spring rate for the type pf riding you do is going to be a somewhat subjective process.

Don't know if that helped or hurt, but I think using set formulas like those that are often espoused by ex-racers is detrimental to finding the best suspension setup for real world road riders

 

[SkooterG]

Well the terms as I was taught them:

Free Sag: Just the bike

Static Sag: Bike and rider

Dynamic Sag: Amount of sag when bike is moving and leaned over in a corner. (Obviously not measurable)

Guess that's not the norm?