Setting Static/Dynamic Sag

Having finally finished the installation of my new Wilbers springs and shock, it was time to select the initial suspension settings. There's a ton of good suspension info out there, most of which has probably been referenced on this forum. Having read every article I could locate, I defaulted to the general guidelines that were provided with my Wilbers package. Here's how I did it. YMMV.

Static Sag/The Front: Wilbers recommends a "road" setting (as opposed to "race") static sag of approximately 25-30% of the total maximum suspension travel. Therefore, with a fork stroke of 135mm, I was looking for a static sag in the range of 33.8-40.5mm. First, I got some help from my very capable wife. She took an initial measurement from the top of the fork seal to the bottom of the lower triple clamp, while I elevated the front wheel to fully extend the suspension. We compared this measurement to six additional measurements: full soft (preload adjusters backed fully up), 4 lines showing, 3 lines showing, etc. to full hard (no lines showing, preload adjusters flush with top of the fork cap). As you can see from the following graph, static sag varied from 31.9-45.3, full hard to full soft. This range works out to be 24-34%, nicely bracketing the range that I was looking for.



Static Sag/The Rear: Wilbers recommends a setting of 10-15% of total maximum suspension. Rear stroke=125mm; therefore, desired static sag range is 12.5-18.75mm. First, I made a "V" with two short pieces of electrical tape and placed the apex of the "V" on the fender plastic directly above the rear axle. While the bike was on the center stand I took an initial measurement from the axle nut with the suspension fully extended. This is the measurement that I compared to all other measurements. My shock has the remote preload adjuster. While determining the factory setting on the adjuster, I learned that there is a discernable detent "click" for every 180 degrees of turn. For that reason I decided to take readings for every 1/2 turn of the knob. There turned out to be 9 full turns plus a little on either side for full hard and full soft. Per the chart below, I measured a static sag of 14.3-29.4mm, full hard to full soft, which works out to a range of approximately 11-24% of the total stroke. (This sounds like too soft a spring to me, but it's a bit early to know for sure as I haven't test ridden the bike yet. According to my paperwork, my spring is a 59/59-95-150. My rider weight is 180, including riding gear. Typical cargo weight is 35 pounds. I've sent Klaus an e-mail to get his thoughts.)



Dynamic Sag: Based on the above static sag data, I selected a setting of 3 rings showing (40.1mm) for the forks and 3 turns off of full hard (19mm) for the shock, as starting point to find a suitable dynamic sag. According to the Wilbers info, the goal for dynamic sag is about 33% of total stroke. After a series of measurements and adjustments, I ended up setting the fork preload at 4 lines showing and the shock preload at 1 turn off of full hard, yielding percentages of 32 and 35.5, respectively. (Again, my settings are merely pre-test ride starting points.)

Compression and rebound came factory preset on the Wilbers shock. I will make no changes on those adjusters until I'm satisfied with sag and the fore and aft attitude of the bike. For the compression and rebound settings on the forks, I will probably center everthing and refine it from there.

I'll post a follow up when I know more.

Great info, keep us informed of your findings and thanks for teaching me a new phrase "Dynamic Sag"....(smile) I will use it tactfully!

Having finally finished the installation of my new Wilbers springs and shock, it was time to select the initial suspension settings. There's a ton of good suspension info out there, most of which has probably been referenced on this forum. Having read every article I could locate, I defaulted to the general guidelines that were provided with my Wilbers package. Here's how I did it. YMMV.<snip>

Static Sag/The Rear: Wilbers recommends a setting of 10-15% of total maximum suspension. Rear stroke=125mm; therefore, desired static sag range is 12.5-18.75mm.

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YIKES!!! Can that be right?? 1/2" - 3/4" static sag in the rear? Seems awfully tight to me. Is our local suspension guru out there? Lee, can you comment on this? I thought 20% - 25% were good numbers which would put it at 1" or a tick over that. What was the static sag as the shock came shipped to you?

Even though I have "OHLINS" and have defected to the other side from all of you Wilburs guys, dont hold it against me.

When I set the sag for the front here is what I did differently.

1. put the bike on the center stand and sit back to get the wheel off of the ground. Measure the full extended length. This is the top of the stroke.

2. COMPRESS the front end. Have another person push down on the front end and get this measurement. This is the bottom of the stroke.

3. Let the bike settle, with the rider/Owner on the bike while in the most common riding position. Try to get the bike to settle into the mid stroke or at whatever percentage you want it in. If it sags too low, or too close to the bottom, then tighten the preload adjustment. Make less lines show at the top of the shock. This will raise the shock and front end into the desired stroke zone. Mine is a little higher in the stroke then mid stroke while sitting in position. I guess it is about 30-40% squished. If it settles too high in the stroke then loosen up the preload; more lines showing.

Do the same procedure for the rear. Full squish, measure, full extend, measure, hop on and settle, preload for mid stroke of the shock or whatever % of squish you want.

Now all you need to do is to set the damping.

I was bogged down with the terminology of compression and rebound attitude until someone at Racetech told me the key to success.

Ask yourself what you want to happen faster or slower. If it is compressing too fast and bottoming out with a bump then you want to turn up the compression damping tighter. If it is not compressing fast enough and feels harsh then turn it down looser.

If it is rebounding too fast and the front end is rearing up after hitting a bump turn the rebound damping stronger/tighter. If it is packing down with multiple bumps loosen the rebound damping so it will recover faster.

I like when the front end rebounds just a bit faster then the rear end shock. Just a bit is all.

At this setting, I can go behind a truck, on the freeway, after dark and notice that the headlight beam stays steady without moving up and down. I notice that the bike feels great in the twisties and I can feel the suspension compress in the turns and the bike carves evenly. Dosnt fall in or out, just tracks great. No more diving stops either.

First of all, Leghorn didn't mention measuring stiction on the front end. It's crucial to account for that amount or else any measurements made will be different for each person who checks sag.

To answer DD's question on sag, we recommend a "range" of numbers that are closer to race standards for a baseline. We've found it also works very well for street use unless the road pavement conditions are pitifully bad. For the front, the bike supporting it's own weight and being balanced straight up and down, we like to see 20-25mm of sag with stiction accounted for. At the rear, we like to see 10-15mm. With the rider aboard, we like to see 30-35mm in front and 30-35mm at the rear. Again, these are baseline numbers and their sole purpose is to help the suspension tuner select the proper springs. If you can't get these numbers then you should decide on your course of action - either softer springs, or stiffer springs. You also need to combine that information with how much preload you need to apply to those springs in order to get into those ranges. If you have to apply too much preload to a spring in order to get it close to the desired sag, then the spring is too soft. If you have to run too little preload to the spring to get close, then the spring is too stiff.

One of the most important things to consider is not every rider likes the same setup as another rider. Road conditions, rough or smooth play a part in the suspension settings since a lot of it is about compromise. There is no perfect setup for ALL conditions.

Getting back to measuring stiction - to accurately measure stiction, you need to lift up on the end of the bike you are measuring and let the bike down slowly. This will be your "stuck-up" position. Measure it and write it down. We'll call that F2. Then, push down on the suspension at that end and let it rise slowly. This is the "stuck-down" position. Measure it and write it down. Call it F3. The actual sag will be the average of F2 and F3 subtracted from the fully extended (F1) measurement. We can express that in an equation - F1 - (F2+F3/2) = sag

Do this for sag with and without the rider aboard. It takes 3 people to accurately measure sag. One person to balance the bike from the opposite end that is being measured, the rider in their normal riding position when measuring the "with rider aboard", and the person measuring the actual sag. Doing it any other way will not provide you with repeatable measurements.

Hopefully, this will help you guys.

Forgot to answer one of your questions DD. With my Penske 8981 and a 950 lb/inch spring and 9mm of preload applied to the spring, we measured 11.5 mm of static sag at the rear. With me aboard, we measured 32.5 mm. The ride felt firm and very well controlled with that spring and that setting 1-up or 2-up but over the worst of the bumps, it felt just a bit harsh. I've since backed off the preload to 7mm and it is better. I've not measured sag again with less preload dialed in. I'm pretty confident that spring is close for me at 215 lbs without gear. We've discussed it at the shop and consider a 900 lb/inch spring to be our standard starting point for average weight riders that ride the FJR alone most of the time. 2-up riding most of the time you'd have a choice based on your weight + the weight of your passenger + the amount of luggage/gear you normally ride with.

I'll be taking the forks into the shop today to prepare them for the AK-20 cartridge kit install. I cannot wait to get this done.

Thanks for all the info! You're right, sportryder, we didn't account for stiction. I knew about those measurements but thought that a shortcut wouldn't matter so much. I stand corrected. (On the other hand, did you notice on the graph how linear the measurements came out?)

I think that I'll do the whole thing again, especially for the rear, because I want to make the right decision before Spring (no pun ) on whether to substitute a stronger spring. Removing and reinstalling the shock is not a job that I relish -- I've got the Wilbers model with the remote hi/lo compression adjuster and, with the remote preload arm to also deal with and ABS in the way, it's a challenge to get everything into place without scuffing things up. As they used to say in the navy, another opportunity to excel! :blink:

Thanks for all the info! You're right, sportryder, we didn't account for stiction. I knew about those measurements but thought that a shortcut wouldn't matter so much. I stand corrected. (On the other hand, did you notice on the graph how linear the measurements came out?)
I think that I'll do the whole thing again, especially for the rear, because I want to make the right decision before Spring (no pun ) on whether to substitute a stronger spring. Removing and reinstalling the shock is not a job that I relish -- I've got the Wilbers model with the remote hi/lo compression adjuster and, with the remote preload arm to also deal with and ABS in the way, it's a challenge to get everything into place without scuffing things up. As they used to say in the navy, another opportunity to excel! :blink:

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The FJR has pretty low numbers for stiction if the pivot points out back are lubed correctly. We measured 1mm of stiction in the rear on my '05.

Out front, we measured 5mm of stiction on my FJR which is good for forks in general and normal for most standard right-side-up forks. Now OTOH, USD forks vary quite a bit and tend to average around 9-10mm.

The front is where you might see some variance on stiction with the FJR but with the heavier bikes, it takes quite a bit of stiction to make a substantial change in the measurements. Some guys just bounce the front end gently and measure it after it settles to a stop. This could work ok for the heavier bikes, but in our business, we work on a lot of race bikes that are 1/2 - two-thirds the weight of the FJR. This is why we always account for stiction because it WILL make a difference in what is measured. On the FJR or other heavy bikes with standard fork design (RSU), it might only show up as 1-2mm difference with your sag measurements. Either way, if you are going to go to the trouble of measuring everything then why not do it as precisely as you possibly can?

Thanks for posting your sag measurements and other info Leghorn. Good on ya!

First of all, Leghorn didn't mention measuring stiction on the front end. It's crucial to account for that amount or else any measurements made will be different for each person who checks sag.
To answer DD's question on sag, we recommend a "range" of numbers that are closer to race standards for a baseline. We've found it also works very well for street use unless the road pavement conditions are pitifully bad. For the front, the bike supporting it's own weight and being balanced straight up and down, we like to see 20-25mm of sag with stiction accounted for. At the rear, we like to see 10-15mm. With the rider aboard, we like to see 30-35mm in front and 30-35mm at the rear.

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After you said that, I went back and re-read the original post. I just realized that nowhere does he say that he was astride the bike. Hence my confusion. The numbers I typically use are with rider aboard...never actually tried it without. Does that even work?

And yes, I always compensate for stiction by taking two measurements...one by lifting up and letting it fall, one by pushing it down and letting it rise...split the difference. Thanks for responding Lee.

First of all, Leghorn didn't mention measuring stiction on the front end.  It's crucial to account for that amount or else any measurements made will be different for each person who checks sag. 
To answer DD's question on sag, we recommend a "range" of numbers that are closer to race standards for a baseline.  We've found it also works very well for street use unless the road pavement conditions are pitifully bad.  For the front, the bike supporting it's own weight and being balanced straight up and down, we like to see 20-25mm of sag with stiction accounted for.  At the rear, we like to see 10-15mm.  With the rider aboard, we like to see 30-35mm in front and 30-35mm at the rear.

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After you said that, I went back and re-read the original post. I just realized that nowhere does he say that he was astride the bike. Hence my confusion. The numbers I typically use are with rider aboard...never actually tried it without. Does that even work?

And yes, I always compensate for stiction by taking two measurements...one by lifting up and letting it fall, one by pushing it down and letting it rise...split the difference. Thanks for responding Lee.

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DD - I believe Leghorn used the terms static and dynamic sag and reported his measurements. Without being familiar with what he actually meant, I can only guess he was using static sag as the bike supporting it's own weight and dynamic sag was with him aboard. I may be wrong, but his reported sag numbers suggest that was what he was telling us.

You're right, sportryder, "static" and "dynamic" sag were the terms used in the Wilbers paperwork and I went with it. Static = bike with no rider. Dynamic = bike with rider in riding position with full riding gear.

As a follow up, Klaus asked for a couple of additional measurements: Dynamic sag with preload at full stiff (47.6mm) and preload a full soft (61.1mm). He also asked that I recheck my own weight (186.5 in full gear). Having received that info, he suggested that we replace the spring. My current spring is a "95"; it looks like I need something between a 110-115. Anyway, Ive pulled the shock assembly and as of today it's on its way to Wilbers for the replacement.

As a follow up, Klaus asked for a couple of additional measurements: Dynamic sag with preload at full stiff (47.6mm) and preload a full soft (61.1mm).  He also asked that I recheck my own weight (186.5 in full gear).  Having received that info, he suggested that we replace the spring.  My current spring is a "95"; it looks like I need something between a 110-115.  Anyway, Ive pulled the shock assembly and as of today it's on its way to Wilbers for the replacement.

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I'm a little surprised to see Wilbers are still fitting this spring for your weight range of 185lb's. The numbers you have published are what I was seeing when I first got mine. Did you also feel how much the rear would squat when you were hard on the gas?

FYI I went from a .95kg to 11.0kg and am now very happy. It is firm when solo, but if you get all options, dialing in the high speed compression makes the difference. I see that you mention the 11.5kg spring in your post. I think this spring will be too stiff for you, unless there's some information you have not added that would require this? I don't have all the pertenant info in front of me, but going from .95kg to 11.0kg with equal amounts of preload will give you an additional load capacity of 80lb's IIRC. If you prefer a less sporty ride and don't load up with a passenger and luggage, the 10.5kg would probably be the better choice for you.

I often wonder how many other's may be unknowingly riding around on shock that is incorrectly sprung for their weight?

You're right about the squat, skyway. It felt abnormally soft, sort of like you might expect a busted suspension to feel, this from just sitting on the bike. On the gas, I can't imagine how it would have handled, but I never took it out -- the weather here hasn't been cooperative.

I don't know beans about spring technology, at least in terms of how to calculate the correct spring. Your suggestions are helpful. I want the ride to be plush, but firm and controlled at the same time. Ideally, I would typically ride solo with the preload at or almost at full soft. Then I would have plenty of preload left for luggage, pillion, track, twisties, etc. I have all the compression/rebound/ride height options, but as you know, it all starts with the spring. I'm going to have to rely on you, sportryder, Klaus and the other experts for that.

I want the ride to be plush, but firm and controlled at the same time.  Ideally, I would typically ride solo with the preload at or almost at full soft.  Then I would have plenty of preload left for luggage, pillion, track, twisties, etc.  I have all the compression/rebound/ride height options, but as you know, it all starts with the spring.

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It looks like you've covered about every riding scenario there is.

Here's my choice and why. Go with the 11.0kg spring for now. Ask Klaus to set it up so that with just you on the bike, sag will be about 40mm with zero added remote preload. Since why would you ever want to ride any softer? I say this because locally where I live, I ride lots and lots and lots (did I mention lots? :lol: ) of tight technical highways, solo and 2-up. Anything less than the 11.0kg spring will not cut it IMO.

When you get the shock installed, play around with the settings, and I don't mean 1 or 2 clicks up and down, go all the way from min to max to really get a feel with whats going on with each setting. Then begin to fine tune and make notes on solo, 2-up etc. Once you dial it in for your riding styles, you will realise that the Wilbers is leaps and bounds better than the stock shock.

I often wonder how many other's may be unknowingly riding around on shock that is incorrectly sprung for their weight?

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Uh, that would be me. With all the incorrect spring weights reported already, I can't help but wonder if mine is undersprung also as I have the .95kg spring also.

One of these days I will get around to measuring everything.

I ended up with the 11kg spring as well. I was not happy having 3/4 of preload used for a weekend jaunt. I now have 1/8 preload solo and it is smooth. Love it. I had to send mine back to up the spring rate.

DRJFJR

I often wonder how many other's may be unknowingly riding around on shock that is incorrectly sprung for their weight?

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Uh, that would be me. With all the incorrect spring weights reported already, I can't help but wonder if mine is undersprung also as I have the .95kg spring also.

One of these days I will get around to measuring everything.

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For me the .95kg spring felt weaker than the stock spring. I would suggest you get vectervp1 over to your place and check your sag #'s.

There is a possibility that given the miles you get out of a set of tires, :blink: you may not have noticed the difference?

For me the .95kg spring felt weaker than the stock spring.  I would suggest you get vectervp1 over to your place and check your sag #'s.
There is a possibility that given the miles you get out of a set of tires, :blink: you may not have noticed the difference?

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My Wilbers is definitely stiffer than the stock shock that I replaced at 36,000 miles. The first time I took it off the centerstand I realized it was stiffer as the rear did not compress as much. It felt stiffer riding also.

Also, when vectervp1 and I switched FJRs this past November on the way home from SPANK, he told me he immediately noticed a positive difference in the handling of my Wilbers equipped FJR compared to his 05 FJR with stock shock and approximately 15,000 miles. (Bikes were loaded up in rally mode though only 1 up) I noticed the difference too. That ride I believe is what convinced him to spend the $$$$ for one. And my Wilbers had about 19,000 miles on it then if that makes any difference.

It was definitely an improvement, just wondering if is truly the correct spring rate since so many others were not.

Some day I will get around to checking it. Or better yet, you should come visit and help me do that as well as install brake lines, Audiovox CC, Autocomm, Garmin GPS, and.........clean my bathroom as well.

Thanks, skyway. Your reasoning seems sound. I'll get in touch with Klaus and tell him about your recommendation for the 11.0 spring. I take it from your certainty that you and I are similar in riding weight. (I'm at 186.5 lb with full riding gear.) Can you confirm -- I would like to include that info in my e-mail to Klaus.