Suspension Setup

Hi everyone,

Last week i installed some new fork springs on my bike and i thought i would write a quick report in case any one is on the verge of doing and needs extra convincing.

My bike is a 2009 with 6000miles, i weight 180 lbs and measure 6'2".

From the beginning i always felt that the forks were to soft, like many people on the forum i didn't like the dive i would get under braking and the unsettling wobble i got whenever i made any mid turn adjustments.

I changed the oil to 15w (actually it was 10w!) last summer, which really helped, but i still wanted to change the springs and get the setup done properly.

I ordered Racetech springs, they recommended 0.88 for street and 0.92 for racing so i went with 0.90.
The installation was pretty easy, i had bought a length of cheap tubing to experiment on spacer length with, ended up having to tear everything down 3 times before i got the spacer length correct (175mm). I think all together it took around 3 hours from start to finish.

I first wanted to go with 0.95 springs but i really don't regret going with 0.90, they give a great ride, they don't feel to hard, but do get rid of any unwanted dive. More importantly the bike is a lot more stable in turns, it also is a bit more direct in turns and wobbles less in general.
On very bad roads things do get a bit rough though, it gets a bit bouncy in the rear. I suspect that the better reactions of the front now makes the short coming of the rear more obvious.

In the end i ended up with:

Front static sag: 20mm
Front rider sag: 32mm
Cable tie on the fork shows i have 1/2" of travel left before i bottom out.

Rear preload on 5
Rear static sag: 7mm
Rear rider sag: 30mm

Now, although those numbers are pretty much exactly what i was aiming for, and the ride is a lot better than stock, i can't help but wonder how much better it would be with some emulators in the front and a Nitron shock in the rear...

If anybody has done the front in two stages, how much improvement did the gold valves do compared to springs alone?
Is it worth upgrading the shock?

Since threads are better with pics, here isone, since these pics the bike has had new pegs, and an FZ1 bar...

I did the spring and oil change and thought the same as you, what would the next step be? Instead of emulators, I went with the r6s fork swap.

Carlos840 said:

Hi everyone,

Last week i installed some new fork springs on my bike and i thought i would write a quick report in case any one is on the verge of doing and needs extra convincing.

My bike is a 2009 with 6000miles, i weight 180 lbs and measure 6'2".

From the beginning i always felt that the forks were to soft, like many people on the forum i didn't like the dive i would get under braking and the unsettling wobble i got whenever i made any mid turn adjustments.

I changed the oil to 15w last summer, which really helped, but i still wanted to change the springs and get the setup done properly.

I ordered Racetech springs, they recommended 0.88 for street and 0.92 for racing so i went with 0.90.
The installation was pretty easy, i had bought a length of cheap tubing to experiment on spacer length with, ended up having to tear everything down 3 times before i got the spacer length correct (175mm). I think all together it took around 3 hours from start to finish.

I first wanted to go with 0.95 springs but i really don't regret going with 0.90, they give a great ride, they don't feel to hard, but do get rid of any unwanted dive. More importantly the bike is a lot more stable in turns, it also is a bit more direct in turns and wobbles less in general.
On very bad roads things do get a bit rough though, it gets a bit bouncy in the rear. I suspect that the better reactions of the front now makes the short coming of the rear more obvious.

In the end i ended up with:

Front static sag: 20mm
Front rider sag: 32mm
Cable tie on the fork shows i have 1/2" of travel left before i bottom out.

Rear preload on 5
Rear static sag: 7mm
Rear rider sag: 30mm

Now, although those numbers are pretty much exactly what i was aiming for, and the ride is a lot better than stock, i can't help but wonder how much better it would be with some emulators in the front and a Nitron shock in the rear...

If anybody has done the front in two stages, how much improvement did the gold valves do compared to springs alone?
Is it worth upgrading the shock?

Since threads are better with pics, here isone, since these pics the bike has had new pegs, and an FZ1 bar...

Click to expand...

Thanks for the write up!
That really helps people see progress, time required, money and return on all of above!

Glad you shared!

FWIW: I also have R6 forks (2004), R1 rear shock (2003 - revlaved, FZ6 Spring) and pretty close to the same rider sag numbers you post. Results are AMAZING and it really makes the bike a joy to ride as it corrects allot of bad behavior!

Regards,
FI

FinalImpact said:

Thanks for the write up!
That really helps people see progress, time required, money and return on all of above!

Glad you shared!

FWIW: I also have R6 forks (2004), R1 rear shock (2003 - revlaved, FZ6 Spring) and pretty close to the same rider sag numbers you post. Results are AMAZING and it really makes the bike a joy to ride as it corrects allot of bad behavior!

Regards,
FI

Click to expand...

Glad i'm able to help...

Number wise, i am happy.
In a perfect world i think the rear could do with a stiffer spring, i would want to have a bit less rear rider sag. The preload set to 6 would give me 25mm rider sag, but the static sag ends up being close to zero, which i don't want.

Although i really want to see what emulators and a new shock would feel like, I don't think my skills are good enough to make the most of them.
Next, brake levers and SS hoses!

Regarding value for money i would rate the springs/oil upgrade right up there!
I definitely is in my top three mods, i would say number one is the 15t sprocket, number 2 the FZ1 bar and number 3 has to be the spring/oil.

Carlos840 said:

Glad i'm able to help...

Number wise, i am happy.
In a perfect world i think the rear could do with a stiffer spring, i would want to have a bit less rear rider sag. The preload set to 6 would give me 25mm rider sag, but the static sag ends up being close to zero, which i don't want.

Although i really want to see what emulators and a new shock would feel like, I don't think my skills are good enough to make the most of them.
Next, brake levers and SS hoses!

Regarding value for money i would rate the springs/oil upgrade right up there!
I definitely is in my top three mods, i would say number one is the 15t sprocket, number 2 the FZ1 bar and number 3 has to be the spring/oil.

Click to expand...

What have you learned or what lead you to believe the static sag being low (zero) has any impact? I've never heard of that being a concern.

Front of mine has 0.88kg/mm rates and sag is 32 mm
Rear R1 w/OEM spring, 29 mm sag.
Both ends now have compression and rebound damping and work very well together. Its an option but it not without cost. With a fleebay shock, revalve, and adjusting collar, it could be 2 - $300 usd. Thread: http://www.600riders.com/forum/fz6-...-alternatives-how-install-r1-shock-w-pic.html

FinalImpact said:

What have you learned or what lead you to believe the static sag being low (zero) has any impact? I've never heard of that being a concern.

Front of mine has 0.88kg/mm rates and sag is 32 mm
Rear R1 w/OEM spring, 29 mm sag.
Both ends now have compression and rebound damping and work very well together. Its an option but it not without cost. With a fleebay shock, revalve, and adjusting collar, it could be 2 - $300 usd. Thread: http://www.600riders.com/forum/fz6-...-alternatives-how-install-r1-shock-w-pic.html

Click to expand...

I did do a lot of reading on suspension setup and basically from what i understand the relation between static (free) sag and rider (race) sag allows you to determine if your spring rates are correct.

"The rate of the spring is critical. If desired Rider Sag is 35mm and desired rider contribution to the sag is 15mm, then that means Free Sag should be 20mm. Any spring will give you 35mm of Rider Sag, given some preload position, but only one spring (rate) will also give 20mm Free Sag with the same preload position. In other words, given specific goal numbers, only one correct spring rate exists. "

The general rule being that you want around 30-35mm of rider sag in the front, and 25-30 in the rear. If your springs are correct for your weight, you should be able to get these numbers while still keeping "correct" free sag numbers, which are around 20mm in the front, and 10mm in the rear.

Now, if your springs are not the correct rate you can still get the same rider sag numbers, but you are going to have to preload your springs a lot more and you are going to end up with weird static sag numbers.

There are a couple problems with that:

-It's not the right way of doing things!
-You increase your chance of topping out your suspension.
-You influence ride height.

"Because preloading the spring too much will make it too stiff in the top of the stroke and will not allow any free sag. By not having any free sag there could be a traction issue during hard extended braking if rear end is close to topping out and the track or road surface becomes uneven then the wheel may not have enough extending travel to fill the void. This equals the rear wheel to not have continuous contact with the surface and the bike will loose traction and become unstable. "

I think that's it...

Basically, i just followed the guidelines of people who know a lot more about suspension than i do! (have look at the Dave Moss videos on youtube!)

In my situation, setting 5 on the back gives me 7mm free sag, and 30mm rider sag.
If i go to 6 i end up with 25mm rider sag, which is good, but only 2mm left of free sag.

It doesn't sound like much, but i could actually feel the difference when doing emergency braking in a car park.
With the rear preload on 6 the rear wheel felt noticeably lighter and bouncier than with the preload on 5.

^^ Very Good!
I never found actual proof in writing but that is all true! What were you saying about not benefiting from better parts? lol What you found and measured does make a huge difference. Now if you get control of the rates of compression and rebound on both ends you'll be way ahead of the game in making your bike work with you and balancing each end such that you and the bike are fluently coupled (couples)!

To many people over-spring the bikes trying to stop dive. Ride height w/w/out rider and getting just the springs set to the proper settings really matters! That's why I was happy to see someone record it all and verify it. PLUS - Should anything change you now have records and basic starting ground.

But ya, truth is I never found literature (or looked for it) as I was so accustomed to dirt bike setup and making them handle what I needed.

I'm just saying, if you find a deal for the early forks or can swing the late model inverted forks, its real sweet to dial it in to a perfect balance. I'm working with my suspension guy to get the rear squat on acceleration, plus chop (rough roads) a little better. I've ran the valving through the ALL motions making so many stops to tweak it and its good but I likely need a shock that has actual high speed control as this doesn't, so its jarring on rough roads but great on 85% of where I ride.

Hats off! Tks

Thanks!

Like you said, so many people over spring the front, most people my weight or even lighter go for heavier springs, I was about to follow that trend but the place i ordered the springs from managed to make me realise it was a bad move.
The dive is to blame on the design of the forks as much as it is on the spring rate, and there is no need to go mental on the spring!

I think the main issue is that not many people take the time to read about suspension, they just assume stronger/stiffer is better.
There are so many different people saying different things, so many different opinions, it really takes time and dedication to read through all of it, and take the information you need from each source.

In case you guys feel like doing some reading, here are a couple websites i found really useful:

Peter Verdone Designs - Motorcycle Springs

Motorcycle Suspension Set-up

Also, i really think it is worth watching the Dave Moss videos on youtube, (two clicks out)


Now, i don't know what my next step will be, i think i will ride next summer with my current setup. I don't think i will do the fork swap, here in europe the forks tend to be more expensive and if i do something more to the front it will be emulators.
I do like the idea of a new shock in the rear, might have to give that a go at some point.

Stupid question, how do you change the rear shock without a center stand?

You guys are the bomb!

Thank you for this post. You have taken a lot of the guess-work and research out of this for me. I am 180lbs. and 6'2" as well, so these numbers really help. I've reached that point in my riding where I can really see the short-comings of the FZ6's suspension, and was wondering what I would do to correct it. For the money this has got to be the best upgrade.

Glad i could help!

If you haven't done it yet, bump the shock preload to 5 and change the fork oil to 15W, it already helps a lot and won't cost you much.
From then on if you want to change the springs it isn't much more work, just take it apart, cut the spacers to 175mm and dump it all in.

If you really want the spacer length to be perfect do what i did, buy a length of cheap tubing, use that to figure out what your exact length should be, and then cut the provided spacer to the right size.

Although we are the same weight, you can't assume your spacer will be exactly the same size as mine, my bike is naked (20lbs lighter) has no rear pegs, an aftermarket exhaust, and my gear is not going to weight the same as yours!

Don't hesitate if you have any questions.

Carlos840 said:

Glad i could help!

If you haven't done it yet, bump the shock preload to 5 and change the fork oil to 15W, it already helps a lot and won't cost you much.
From then on if you want to change the springs it isn't much more work, just take it apart, cut the spacers to 175mm and dump it all in.

If you really want the spacer length to be perfect do what i did, buy a length of cheap tubing, use that to figure out what your exact length should be, and then cut the provided spacer to the right size.

Although we are the same weight, you can't assume your spacer will be exactly the same size as mine, my bike is naked (20lbs lighter) has no rear pegs, an aftermarket exhaust, and my gear is not going to weight the same as yours!

Don't hesitate if you have any questions.

Click to expand...

Is it simply a matter of trial and error to find out what size to cut the spacers to? Like, do you have to keep taking the entire front end apart to readjust it? This is something I'm leaning more towards after looking into the R6/R1 shock.. Seems more affordable, and at this point in my riding career, all I will need anyways.

Yes it is... And yes, you have to tear it down every time...

It took me around 3 hours with a friend, i bought a second length of tubing, followed the instructions given by racetech and cut it to size.
Put everything back together, put my gear on, measure sag, tear everything down, shorten spacer, put everything back together.

At that point i had enough info to get the spacer size correct, so i went to the provided piece of tubing and cut it to the final length, which was a bit shorter than the second one, and put everything back together.

I have to say that the racetech formula put me in the correct range, and i am sure most people would have left it at that and been happy with it.
I am a bit OCD, and i decided i wanted as close to 30mm as possible, which is why it took me 3 times to get it right!
I really wanted to tear it down again and get 30mm exactly, but i think my friend would have killed me, and i doubt anyone can feel the difference between 30mm and 32mm...

Regarding the fork springs vs shock dilemma, i have to say that although the shock is far from great, and i will probably replace mine at some point, the fork springs are by far the weakest link in the stock configuration.
Changing them really makes the bike a lot more stable and better overall. Also, you get a lot more results for your money.
A rear R1/R6 shock would need complete overhaul to work on the FZ6 and i doubt it would cost you less than a set of springs, they would also be useless with stock fork springs.

bdevries said:

Is it simply a matter of trial and error to find out what size to cut the spacers to? Like, do you have to keep taking the entire front end apart to readjust it? This is something I'm leaning more towards after looking into the R6/R1 shock.. Seems more affordable, and at this point in my riding career, all I will need anyways.

Click to expand...

Yamaha did not design the forks to work with 15W oil. I found it so heavy it slowed down the action of the forks so much they could not react to bumps leading to a very harsh ride.

It's better to review viscosity ratings when choosing fork oil. Here's a chart I used to make an informed decision. I marked Yamaha 01 which is what the manufacturer recommends, the Silkolene I went with and where the 15W oils are.

darius said:

Yamaha did not design the forks to work with 15W oil. I found it so heavy it slowed down the action of the forks so much they could not react to bumps leading to a very harsh ride.

It's better to review viscosity ratings when choosing fork oil. Here's a chart I used to make an informed decision. I marked Yamaha 01 which is what the manufacturer recommends, the Silkolene I went with and where the 15W oils are.

Click to expand...

I think this is a very personal and subjective subject!

Since we have no control over rebound and compression, the only way we can affect it is with oil weight.

Personally i find the suspension very scary with the stock oil weight.
It dives all over the place when you brake, it wiggles in turns, it is very unstable.

Changing the oil to 15w got rid of 90% of my issues, it controlled the dive during braking, it got rid of the wiggling, made the bike feel so much more planted.

I have not detected any deterioration of the ride quality, if anything it made it better.

That said, i attach more importance to feedback and feel than to ride comfort.

If you enjoy a bit of spirited riding, it's a no brainer.

If your idea of fun riding is a plush ride, in a straight line, while trying to maintain your rpm under 5k then by all means stay with the pillowy stock weight.

Carlos840 said:

I think this is a very personal and subjective subject!

Since we have no control over rebound and compression, the only way we can affect it is with oil weight.

Personally i find the suspension very scary with the stock oil weight.
It dives all over the place when you brake, it wiggles in turns, it is very unstable.

Changing the oil to 15w got rid of 90% of my issues, it controlled the dive during braking, it got rid of the wiggling, made the bike feel so much more planted.

I have not detected any deterioration of the ride quality, if anything it made it better.

That said, i attach more importance to feedback and feel than to ride comfort.

If you enjoy a bit of spirited riding, it's a no brainer.

If your idea of fun riding is a plush ride, in a straight line, while trying to maintain your rpm under 5k then by all means stay with the pillowy stock weight.

Click to expand...

Wow no need to get defensive. Just advising to take a look at viscosity (CST) and make an informed decision.

darius said:

Wow no need to get defensive. Just advising to take a look at viscosity (CST) and make an informed decision.

Click to expand...

Sorry, I really didn't mean to sound like i was attacking your post, just wanted to make sure he got a voice from both end of the spectrum!

My bad...

I will look into the oil chart stuff tonight when i get home. I am intersted in changing that, but I also figure that if the racetech springs arent too pricey, i may as well do it all while I have it apart anyways!

Carlos840 said:

Sorry, I really didn't mean to sound like i was attacking your post, just wanted to make sure he got a voice from both end of the spectrum!

My bad...

Click to expand...

No worries. :thumbup: You're absolutely right though that riding style should be considered.

Carlos840 said:

Click to expand...

Not that it's on topic, but that's a GOOD looking bike.

thisisbenji said:

Not that it's on topic, but that's a GOOD looking bike.

Click to expand...

Thanks, here is a thread with more recent pictures.

http://www.600riders.com/forum/fz6-general-discussion/53102-final-motorcycle-update.html

(just realised you already commented on the other thread, my bad!)