Setting Suspension Sag

[Fudge]

OK I spent yesterday setting up my rider sag numbers on both my FJ and my neighbors FJR and I wanted to run something by the group. When adjusting for rider sag do you use a set 'mm' measurement (like 28-35mm), or a percent of total suspension travel? My theory is the percent of total suspension travel is the way to go.

While reading about proper suspension setup it notes that you should set your sag to approximately 30% of total suspension travel. Since my bike has 150mm total front travel, I adjusted to 45mm of front sag, exactly 30%. And in the rear I have 120mm of travel, and I adjusted to 36mm sag, which is also exactly 30%.

For my neighbors FJR the total front travel is 137mm and we set the front for 41mm rider sag with 1 line of adjustment left showing, for 30% of total travel. Total rear travel is 122mm and the rider sag ended up being 35mm or 28% of total travel.

If I were to follow the mm theory I would have to tighten up the front to get to the 28-35mm recommended sag. This would put both bikes at less than 30% and closer to 20% of the total suspension travel which doesn't seem right.

 

[sportryder]

Something a lot of people do not realize is most forks now have a hydraulic bottom out device or "oil lock" installed either on the cartridge rod or at the bottom of the fork tube. This device comes into play during the last 3/4 to 1" of travel. It's purpose is to prevent a hard metallic "clank" when the forks do actually bottom. So, keeping this in mind, if you go by total fork travel and use the 30 percent rule, you are cheating yourself out of having enough suspension travel in reserve to absorb medium to larger bumps.

 

[Leghorn]

I'm no guru, but I use the percentage method for initial setup and then adjust to taste after test rides. Wilbers recommends that static sag be set to 25-30% and 10-15% of total travel, front and rear, respectively, and about 33% front and rear for dynamic sag. I think the key is to establish a starting point, keep good notes and fine-tune from known settings to get what you want.

 

[sportryder]

Total travel according to the service manual is 135mm. The hydraulic bottom out device comes into play during the last 25mm of fork travel during high velocity fork movements like hitting the exiting side of a pothole or over a larger bump. So usuable fork travel is around 110mm. Using the upper end of your static sag range of 30% leaves 77mm of fork travel that is usuable and you haven't added the rider yet. If the springs are correct and you add the rider, you can subtract another 10-20 mm of usuable travel. That puts you down around 2.5 inches of fork travel remaining that you are riding on before you get a soft bottom out from the hydraulic oil lock in the bottom of the fork. Apply the brakes and lose another inch or more and you have an inch or less to absorb a bump. It's all good if the roads are smooth. Does anyone know where that might be here in the US of A?

Static and dynamic sag rules have been a baseline to work with for a long time. However, they do not take into account road surface conditions experienced on a daily basis by the majority of street riders. They also do not take into account the hydraulic bottom out devices present in most modern forks. Because of that, many suspension shops do a couple of things to extend available fork travel. They run stiffer springs and internally preload them less. This alone extends the reserves of usuable fork travel without making the ride harsh. They also partially disable the "oil locks" present in modern fork legs so usuable travel reserves are extended a bit more.

For the guys that follow the old sag rules, a general improvement to suspension performance is experienced. But, there is still a substantial improvement to be made from there. I don't speak about any of these things here to put down others or other products. Everyone has their opinion of what is good for them. I'm simply trying to share this information to other FJR owners so they can maybe try thinking outside of the box.

I don't receive a commission on any product sold at our company. We have plenty of business already so it's not that either. But, as an FJR1300 owner with our full zoot suspension setup, I like to see other FJR owners happy with their suspension setup. If I can help that happen in any way, it would please me and you guys would also benefit.

 

[Klunkshift]

Somebody tell me if this would work for front suspension setting.

I can see the dust ring on the fork tube indicating maximum suspension travel during regular use. If you can’t see the dust ring, substitute for cable tie method to mark the maximum suspension travel for a given set up

1) Put bike on center stand,raise front wheel, and measure distance from fork seal to dust ring. Mine is 95 mm with the current set-up. This means I am using 95 mm of the fork available travel during my rides (my ride style is non-aggressive).

2) Maximum fork travel is 135 mm (by FJR specs), thus I have about 40 mm of travel left.

3) From this 40mm, about 25mm will get me to the hydraulic oil lock phase. This means I have a “fork travel savings” of about 15mm to absorb a big unusual bump.

The suspension feels really good (for me) this way. Firm without being obnoxious. It is a different world with the Wilbers springs. I am using Sylkolene RSF 7.5 , which has about the same viscosity as Bel Ray 10, with 100mm of air gap. My weight is close to 200lb ready to ride.

 

[sportryder]

The suspension feels really good (for me) this way. Firm without being obnoxious. It is a different world with the Wilbers springs. I am using Sylkolene RSF 7.5 , which has about the same viscosity as Bel Ray 10, with 100mm of air gap. My weight is close to 200lb ready to ride.

To me, your complete post presents a valid way of evaluating your front suspension performance. It's giving you a way to collect the data in order to tune further. The only thing I would be curious to know is how much you have tried to use as much fork travel as possible. Severe braking? Rough roads? Braking over bumpy sections of pavement? Only you know that type of information. Knowing the answers to those questions would tell you just how much reserves you actually have.

If you like the way it feels then go with it. If your average riding is leaving you with this reserve of suspension travel, you could try experimenting with the height of the air gap and/or fork oil viscosity. A thinner oil might provide better bump compliance with the OEM compression valving. A taller air gap would bring the progressive nature of the air spring into play just a bit later. More suspension travel is a good thing. The trickiest part is using nearly all of your suspension travel without bottoming. It's a balancing act but worth it when you get it just right.

 

[sanqhar]

The approach here is empirical for the front.

Zip tie the legs, go for a ride, adjust suspension, reset zip tie and go for another ride.

https://www.moto-racing.co.uk/Guides/motorc...tup.htm#DAMPING

 

[zzkenoman]

Total travel according to the service manual is 135mm. The hydraulic bottom out device comes into play during the last 25mm of fork travel during high velocity fork movements like hitting the exiting side of a pothole or over a larger bump. So usuable fork travel is around 110mm. Using the upper end of your static sag range of 30% leaves 77mm of fork travel that is usuable and you haven't added the rider yet. If the springs are correct and you add the rider, you can subtract another 10-20 mm of usuable travel. That puts you down around 2.5 inches of fork travel remaining that you are riding on before you get a soft bottom out from the hydraulic oil lock in the bottom of the fork. Apply the brakes and lose another inch or more and you have an inch or less to absorb a bump. It's all good if the roads are smooth. Does anyone know where that might be here in the US of A?
Static and dynamic sag rules have been a baseline to work with for a long time. However, they do not take into account road surface conditions experienced on a daily basis by the majority of street riders. They also do not take into account the hydraulic bottom out devices present in most modern forks. Because of that, many suspension shops do a couple of things to extend available fork travel. They run stiffer springs and internally preload them less. This alone extends the reserves of usuable fork travel without making the ride harsh. They also partially disable the "oil locks" present in modern fork legs so usuable travel reserves are extended a bit more.

For the guys that follow the old sag rules, a general improvement to suspension performance is experienced. But, there is still a substantial improvement to be made from there. I don't speak about any of these things here to put down others or other products. Everyone has their opinion of what is good for them. I'm simply trying to share this information to other FJR owners so they can maybe try thinking outside of the box.

I don't receive a commission on any product sold at our company. We have plenty of business already so it's not that either. But, as an FJR1300 owner with our full zoot suspension setup, I like to see other FJR owners happy with their suspension setup. If I can help that happen in any way, it would please me and you guys would also benefit.

I visited your company web site, and I read the information about your products. How close can I set my stock settings on my FJR to your replacement fork setup? Do you have anyone here, who bought your race/Touring fork system, give us thier opinion in ride differences on real road testing, to help me decide if that is the avenue I want to go to? Would it be easy to install by a novice mechanic like myself?

 

[sportryder]

I visited your company web site, and I read the information about your products. How close can I set my stock settings on my FJR to your replacement fork setup? Do you have anyone here, who bought your race/Touring fork system, give us thier opinion in ride differences on real road testing, to help me decide if that is the avenue I want to go to? Would it be easy to install by a novice mechanic like myself?
zzkenoman - there are a few guys out on the west coast (maybe half a dozen) that have Penske shocks installed along with our AK-20 cartridge kit in their FJR forks. I don't know if they visit this forum or not. Some of them have the top of the line 8987 Penske shock. We sold the kits and shocks to a small motorcycle business owner who did the work and those folks were his customers.

Here on the east side of the US, I might be about the only one with the AK-20 kit up front with a Penske out back. I've put some time in (weather permitting) while working on rear shock spring rates and fine tuning the front end using our new cartridge kit.

The AK-20 kit was designed so a person handy with general mechanical knowledge and tools could perform the work on their own. To get the very best performance, for a couple of models of motorcycles, we recommend that we do the install. The FJR1300 forks could be done by someone handy with tools, but to get the best performance from it, the work envolves just a little more than some people might feel comfortable with. It's not difficult, but it does envolve modification of the hydraulic bottom out device (oil lock) in the bottom of the fork tube. We can gain about 15 mm of usable suspension travel through this mod without risking a hard bottom out. It's not required to do that mod, but it's one of those extra things we would do to maximize the performance of the FJR forks.

 

[zzkenoman]

I visited your company web site, and I read the information about your products. How close can I set my stock settings on my FJR to your replacement fork setup? Do you have anyone here, who bought your race/Touring fork system, give us thier opinion in ride differences on real road testing, to help me decide if that is the avenue I want to go to? Would it be easy to install by a novice mechanic like myself?
zzkenoman - there are a few guys out on the west coast (maybe half a dozen) that have Penske shocks installed along with our AK-20 cartridge kit in their FJR forks. I don't know if they visit this forum or not. Some of them have the top of the line 8987 Penske shock. We sold the kits and shocks to a small motorcycle business owner who did the work and those folks were his customers.

Here on the east side of the US, I might be about the only one with the AK-20 kit up front with a Penske out back. I've put some time in (weather permitting) while working on rear shock spring rates and fine tuning the front end using our new cartridge kit.

The AK-20 kit was designed so a person handy with general mechanical knowledge and tools could perform the work on their own. To get the very best performance, for a couple of models of motorcycles, we recommend that we do the install. The FJR1300 forks could be done by someone handy with tools, but to get the best performance from it, the work envolves just a little more than some people might feel comfortable with. It's not difficult, but it does envolve modification of the hydraulic bottom out device (oil lock) in the bottom of the fork tube. We can gain about 15 mm of usable suspension travel through this mod without risking a hard bottom out. It's not required to do that mod, but it's one of those extra things we would do to maximize the performance of the FJR forks.

I wish I knew who could install them here, I'll email you when time comes to buy your system. Looks very promising since its what I've been looking for, thanks for the info.

 

[sportryder]

zzkenoman - Recently, a company out in Palo Alto became one of our Axxion centers. Their company name is Aftershocks. Here is a link to their web-site:

https://www.aftershocks-suspension.com/pages/home.htm

The owner of that company is Phil Douglas and he is well respected for his work. You might want to contact him. I know he is north of you a good ways but the turn around time should be much less than shipping your forks all the way to the east coast.

 

[madmike2]

Hmmmm, Palo ALto. Hmmmmm, really close to me. Hmmmmm, might be the next major farkle.