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Moved from the ecu thread:

suspension talk has got me thinking. FYI, I am ~220lbs, and I have the stock settings fully hard. I ride what I think is very aggressively, in the city that is known for crappy roads...like mega pot holes, street car tracks, and cobblestones. By aggressively, I mean I have 1 wheel off the ground about half the time (not quite, but close, lol) and I have scrubbed all of my rear tire....I ride fast and angry, like all the time.

That being said, I have not been bothered that much by the suspension...yeah, I guess it's a little soft...but it does nicely soaking up the big bumps at every intersection. Yeah, sometimes the rear slides out, but it adds to the fun. I've never been in a situation that I've though "woah, my crappy suspension almost caused me to bite it"
That being said, I already have a zx6rr shock that I'm ready to install, and I'm seriously considering the stoltec spring upgrades....mostly because of peer pressure I guess. I am sure most of the track riders here like triple threat and cdolan would smoke me in the twisties...and maybe if I was as proficient as them, or rode in their areas primarily I would feel the suspension lacking too. My concern is that if I do the upgrades, that the suspension will be too stiff and jarring for the city streets that I ride 90% of the time. It's like my buddy who got a decked out BMW 3 series that could haul ass on the back roads, but driving in philly was a miserable experience because of how crappy the roads are here.

So nick and others, how would these upgrades handle the conditions I face most of the time? Thanks
 

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I think it's a common misconception that softer suspension soaks up bumps better than properly setup suspension. Having too much sag for a given bike causes the suspension to be starting (at the sag level) farther along the damping curve, which is incorrect.

Now, with the FZ09 forks for example, there isn't nearly enough damping for the springs that came stock. So the harshness that would come from being into the stiffer part of the damping curve with too much sag isn't really there. On the flip side, there isn't enough rebound damping to keep the front wheel under control. Not a huge deal when going straight, but in a corner, if you hit a big bump it will compress a lot due to improper spring rate and poor compression damping, then it will rebound way too quickly. All of this equates to not keeping the tire properly planted. Also, poor suspension setup puts undue stress on the tire, making it do things it shouldn't, which can lead to loss of traction.

Here's an example. My dirt bike was too softly sprung for my weight. It felt okay to me... I then got proper springs installed for my weight. Yes it's stiffer, but it soaks up bumps way better because it's able to use the damping properly.

A proper ride should be both firm and plush.
 

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Luke, these are good questions that demand a more thorough response for others who have been wondering the same things.

Spring rate selection

The stock fork springs are about 0.75 kg/mm and are very soft by current suspension practices. However, the 'right' spring comes down to more than your weight. Your riding style and intended use play a very large role in spring selection.

There are several targets we try to shoot for when sizing a spring for a rider, but the most well known (and measurable) is sag. While opinions and specs vary from application to application, the general rule is that you should shoot for approximately 1/3 of the available suspension travel for your rider sag. This number applies to front and rear, and is commonly tailored to adjust the bike's effective steering geometry and grip during weight transfer. The idea behind the 1/3 rule is that you want to leave enough available travel in reserve to soak up whatever the road throws at you and enough sag/droop to allow the suspension to extend into dips/holes/cracks/etc. Bottom line is that you want to maintain contact between the tire and road surface; if you break contact, there is no available grip.

Ideally, we'd size a spring that gives you the proper sag with your adjuster in approximately the mid-point of the adjustment. Favoring the low side of the adjustment can reduce harshness under transitionary motions, but this isn't generally a problem unless you really have a lot of preload dialed in. Notice the word 'generally'. There are exceptions to everything.

If you're running around city streets doing 30-60 mph, you're going to need a softer spring than you would if you were braking hard down the front straight of your local track from 150 mph. Given that a spring stores energy, heavier springs are required to store more energy. Not to overly simplify things, but energy generally increases with speed (both vehicle and suspension actuation). You can also make due with less travel on the track than you would on the street...think Baja trophy truck versus F1 car. Both are on the bleeding edge of suspension technology but the applications require two different approaches.

So, 'proper' spring rates are directly related to your riding style, conditions, and personal preference. The personal preference is an important deciding factor, because some people like a firm ride whereas others don't. Neither is wrong...just different.

Damping

Good damping is a critical piece of any suspension set up. The springs are part of the equation, but the damping is what controls the spring's motions. This is where the real money goes when you upgrade your suspension. Tighter tolerances and better designs tend to separate aftermarket suspensions from the original equipment. But, if I were to summarize the requirements of a damper, it would be to provide a smooth, controlled response across a variety of uses. What does that mean? In engineering, we use terms like critically damped, under damped, and over damped. But a picture usually helps:



The job of a damper is to allow the suspension system as a whole to work efficiently...no more or less motion than necessary to absorb bumps. In the case of the FZ-09, the suspension is under damped; the lack of rebound damping is what causes the rider to feel like they are riding a pogo stick or being bucked off the bike. The heavier the rider, the worse the effect. The lack of compression damping is what causes excessive squat during acceleration and dive under braking.

My personal experience is that absolutely everyone can benefit from good damping. This is my personal opinion, and I realize it sounds like a sales pitch. But so be it...I believe in what I sell. The spring rate question is a tricky bit that not always easy to answer. Every application is a different, and many riders often try multiple rates before settling in on a final configuration. So I really hate to say it, but "it depends".
 

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Disclaimer: this is only my opinion- I am not a track rider,yet. I consider myself an average street rider, but I ride mountain roads that are curvy and often dip/bump unexpectedly in the turns.
I will say in town is less important is some ways than on twisty roads. My bike always felt very twitchy on the stock setup, especially in a corner that has a bump or dip. I didn't trust myself to be able to control the direction. When the forks dive it changes the geometry and therefore how quick that the bike wants to turn. Granted, when I bought the FZ, I had been off of a street bike for 15 years. I was pretty uncomfortable pushing it through the mountain roads. Once I upgraded the shock and added the spring and oil to the forks, it immediately felt better and more controlled.

IMO if you mostly ride in town/commute, you might be able to get away with it, but the XZ shock/fork spring upgrade is cheap.
I ride for fun and in different conditions. My bike would have much less use if I hadn't done the upgrades. Worth every penny IMO, and I have the full bling Stoltec Moto setup-LOVE IT! Do what you think you need, hype is a waste of money.
I will tell you that the spring/oil mod will be harsh compared to the re-valve or the cartridges-and yes, I had the springs-then upgraded to the cartridges
 
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I forgot to mention, the better suspension drastically improved the twichyness of the throttle too. Every harsh bump has the potential to make your throttle input "less than smooth" . Don't get me wrong I still got the ecu flash, but it is all connected.
 

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My personal experience is that absolutely everyone can benefit from good damping. This is my personal opinion, and I realize it sounds like a sales pitch. But so be it...I believe in what I sell. The spring rate question is a tricky bit that not always easy to answer. Every application is a different, and many riders often try multiple rates before settling in on a final configuration. So I really hate to say it, but "it depends".
I think for those of us who've been spoiled by good suspension (for any of road course, dirt track/trails, street riding) won't see it as a sales pitch, and totally agree with you. Suspension is the number 1 thing to make any bike work properly.

In terms of track riding, there's no point in having race tires (vs street tires) if your suspension isn't set up right for you. Then after that, there's no point to start tweaking the damping clickers until you have tire warmers for said race tires so that they're working properly. Everything works together for the given bike, rider and ride.
 

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On the FZ09 it is worth every damn penny. It was only half a bike before I upgraded the suspension. There's no way I would keep this bike if I had to keep the stock suspension.
 

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I think the stock suspension of the FZ is just fine for me...... upgrading might be worth while if I was track riding.
 

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Not having a technical background and being a mostly high level thinker - the world of suspension blows my damn mind - i wish someone developed a chart that took into account riding style and weight to recommend which shock to go with. The biggest source of confusion that has prevented me from buying is i have no idea what spring rate to get. Mountain bike suspension is so much easier to figure out IMO (not sure why). Think i need to give the suspension for dummies thread a thorough read.

The second is installation. I was going to get the parts from stoltec and take it down to my local dealer (something small that doesnt have a big impact on my riding i'd be fine with doing - but suspension - i'd rather have someone who knows what they're doing install it).

I'm assuming whatever i order from Stoltec can be installed by a professional (dealer) - but i'm unsure if they will set sag or if that will be on me to understand and adjust (probably should ask them duh :) )
 

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I think the stock suspension of the FZ is just fine for me...... upgrading might be worth while if I was track riding.
IMO, unless you are 120-140 lbs and never ride faster than the speed limit, the stock suspension is way off and compromises the traction available and limits your ability to use the motorcycle to avoid hazards.

Most of the time, when I meet someone that says "the stock suspension is fine" when it clearly is not, indicates they have no idea what a properly set up suspension does actually feel like and what advantages (better traction, better cornering, better control in all situations) that a properly set up suspension provides.

Many THINK an upgraded suspension = stiffer suspension and that is entirely wrong.

An upgraded suspension's job is to keep the tread of the tires in contact with the road at a relatively predictable amount of downforce over all sorts of pavement irregularities. This provides a corresponding relatively predictable amount of traction.

A properly set up suspension should absorb the bumps.
A suspension that is too soft will bottom out and then cause the tire to slide.
A suspension that is too stiff will skip over the bumps, losing traction while not in good contact with the pavement.
 

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Most of the time, when I meet someone that says "the stock suspension is fine" when it clearly is not, indicates they have no idea what a properly set up suspension does actually feel like and what advantages (better traction, better cornering, better control in all situations) that a properly set up suspension provides.
i'm definitely guilty of being in this camp having 2 bikes with bone stock suspension that's likely inadequate - my experience has just been to get used to it because it's all I've known. Same goes for the twitchy throttle - I had that with my SV so this throttle and suspension felt like an upgrade to me when i first started riding it.
 

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Luke, these are good questions that demand a more thorough response for others who have been wondering the same things.

Spring rate selection

The stock fork springs are about 0.75 kg/mm and are very soft by current suspension practices. However, the 'right' spring comes down to more than your weight. Your riding style and intended use play a very large role in spring selection.

There are several targets we try to shoot for when sizing a spring for a rider, but the most well known (and measurable) is sag. While opinions and specs vary from application to application, the general rule is that you should shoot for approximately 1/3 of the available suspension travel for your rider sag. This number applies to front and rear, and is commonly tailored to adjust the bike's effective steering geometry and grip during weight transfer. The idea behind the 1/3 rule is that you want to leave enough available travel in reserve to soak up whatever the road throws at you and enough sag/droop to allow the suspension to extend into dips/holes/cracks/etc. Bottom line is that you want to maintain contact between the tire and road surface; if you break contact, there is no available grip.

Ideally, we'd size a spring that gives you the proper sag with your adjuster in approximately the mid-point of the adjustment. Favoring the low side of the adjustment can reduce harshness under transitionary motions, but this isn't generally a problem unless you really have a lot of preload dialed in. Notice the word 'generally'. There are exceptions to everything.
Different spring rates will net different sags right? So how would you choose a new spring rate for a new shock if the current sag of the stock suspension is all you have or am i understanding this incorrectly?
 

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Different spring rates will net different sags right? So how would you choose a new spring rate for a new shock if the current sag of the stock suspension is all you have or am i understanding this incorrectly?
Riding style and type plays a factor. You can get the proper rider sag with more than one spring rate, but static (just bike) sag will be different, and fully loaded (mid-corner) spring compression will be different. ie, track riding would likely call for a stiffer spring because of higher max-lean angle cornering loads.
 

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Could you please elaborate with details? Your comment would be much more useful with a brief explanation of your riding style, skill level, weight, etc.
Well riding style ranges from putting around town to fast speeds and riding wheelies on back country roads. Skill level, well been riding all sorts of bikes since I was 5, started on a honda 50r. Last bike was an 2005 R1. My weight is 205 with gear.

I dont know if I got a different spring rate than others on here or some kind of oddity for suspension, but a lot of people say suspension is too soft, I on other hand find suspension to hard, almost like a log wagon. I had adjusted front preload .710 and maxed out rebound, out back set preload to minimum and rebound to max. I find the suspension just about right for the kind of riding I do. Soaks up bumps without throwing me out of seat and hasn't bottomed out. Just my thoughts.
 

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I understand people are dancing around a recommendation of what someone should use because of the variables and it may be different from person to person- but is there a baseline to start with?

I see the Penske 8900 has a spring rate of 500lb to 750lb in 50lb increments is there anyone to nail a basic baseline to understand context.

For example -If you were to assume an average rider (not canyon carving, but not riding on highway all the time) at 200lbs -

is that maybe 600lbs (middle of the spectrum)

if you weigh 20lbs more is that an extra xlb increase in spring rate

or if you ride more spiritedly is that the same lb increase as weighing more

or if you weigh 20lbs more and ride spiritedly is that a 100lb increase in spring rate
 

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I'm assuming whatever i order from Stoltec can be installed by a professional (dealer) - but i'm unsure if they will set sag or if that will be on me to understand and adjust (probably should ask them duh :) )
Setting up the suspension (sag and ride height) is fun once you learn how. And then you understand it and know it's done right.

I created a little suspension worksheet almost ten years ago that makes it easy.

Feel free to save it and print as many as you need.

Stoltec Moto (Nick) will be happy to upgrade the forks for you; getting them off is fairly straight-forward. But I would recommend a triple-tree front stand. The shock I wouldn't call an easy job. But with a few tools and patience, it's within most people's abilities. You can always take photos and ask questions on the board for help.

I have the Fork Piston Kit and Penske 8983. The proof is in the riding. Massive improvement in handling and braking. More safe, more fun.

Nick is a very credible person and skilled engineer. I would highly recommend him for your suspension work.
 

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IMHO, suspension upgrades are important when you are really pushing the limits- and sometimes for commuting too- based on individual needs.

I think the stock is fine for city limits or straight forward highway riding- in my experience with my height and weight (5'11.5" x 145lbs) and double up as well. I haven't gone canyon carving yet on this but yes, it is a bit lacking, even with its adjustments. The previous KTM mini thumper that I had has non-adjustable WP 43mm forks and a 6 step spring preload adjustable shocks- out of the box it was great and seemed better than the bigger Yamaha. I never had to adjust anything after setting the shock to 4 and I had insane lean angles in the mountains without ever feeling any dive or nervousness from either end. Another Indian make 150 single that I had was never adjusted and I pushed the limits on the mountain roads and even non-existent roads- and the bike performed perfectly.

Compared to these lithe single mills, there are many differences with the FZ with its extra weight, engine size and outright power. The FZ had a tendency to be bouncy out of the showroom- hardening the shock to about 5/6 and tweaking the front (forgot what I dialed in) has given me good feel without ever being twitchy or nervous. I am sure one ride to the mountains may just change all that. Even with a similar basic set up like the mini KTM, the Duke 690 seems to have a good set up right out of the box. Makes one think what Yamaha is doing wrong.

In the end, one can endlessly change things since we cannot all feel the same thing on the same thing! That's why we call it "customization", don't we? There is no one right answer and we should acknowledge and respect that.
 

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I understand people are dancing around a recommendation of what someone should use because of the variables and it may be different from person to person- but is there a baseline to start with?

I see the Penske 8900 has a spring rate of 500lb to 750lb in 50lb increments is there anyone to nail a basic baseline to understand context.

For example -If you were to assume an average rider (not canyon carving, but not riding on highway all the time) at 200lbs -

is that maybe 600lbs (middle of the spectrum)

if you weigh 20lbs more is that an extra xlb increase in spring rate

or if you ride more spiritedly is that the same lb increase as weighing more

or if you weigh 20lbs more and ride spiritedly is that a 100lb increase in spring rate

I could post a generalized curve for you guys to look at, but honestly, I won't. Not because this is secret rocket science, but because the average consumer will misinterpret the information. The fact is, the spring rate your suspension tuner picks should be based on your weight, modifications to the bike (weight added or removed), riding style, terrain, intended use, budget, and personal preference. After doing this for a while, you can learn a lot from one well-written email or phone conversation. Everyone's needs are different and generalized guidelines usually get people on the wrong springs.
 
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