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Preload and rider sag confusion!

20K views 50 replies 15 participants last post by  Swamper 
#1 ·
Fellow Supersporters! I thought I would make proper use of the additional "S" on my SS and actually tune the suspension. I've gone through threads in this forum and watched tons of Youtube clips on how to set up rider sag and I'm very confused on how much the rider sag should actually be. I've heard/read number ranging from 35-50mm in the front and 25-40 in the rear.

- My impression is that a more accurate aim is to have the rider sag be 30-35% of the wheel travel. Is this correct?
- Do you know what the total wheel travel is front and rear?
- How much should the difference in rider sag be between say track and street riding?
- Is it true that the front rider sag should be higher than the rear? Any specific ratio?

Based on the numbers I'd gotten from various places I thought a reasonable front rider sag would be 40mm but I found that I couldn't go below 43mm of front rider sag with the preload set to maximum. I found this very surprising as I only weigh 61kg => approx. 70kg with gear. As I've read threads on this forum it seems to be a fact though that the front springs are quite soft.

Any input?
 
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#2 · (Edited)
Hi Karishh its good you are going down this road. I think everyone should get to know and understand there suspension as best they can. In saying that you should be able to achieve ideal SAG at your weight ? so to answer some of your points 1) ideal SAG is between 25% - 30% of the spring Travel. 2) Front travel is 130mm therefore your ideal SAG should be between 32.5 - 39 3) Rear Travel is 144mm therefore your ideal SAG should be between 36 - 43.2. 4) your Question on if the front should be higher than the back, I can try and answer this way. Setting your Sag is a combination of having your bike sit in the ideal suspension range and adjusting the ride height to suite. So you will need loads of paper and a pen to jot down your figures as you adjust an play about. I had my bike level and found that it was better (For Me) to have the front of the bike lower than the back. I will not go into the ins and outs as it may throw you off achieving what your after. I would put your bike back to stock settings (which should be close to what you are after) and then create a chart and start adjusting again Front then back, Front then back, Front then back, small changes at a time as one adjustment affects the other. Hope this helped. Please look in your user manual for Front and Rear Spring Travel as I'm pretty sure that the figures I gave you are correct but I'm going from memory.
 
#3 · (Edited)
So I went about first setting the rider sagt and left it at 48mm front and 33mm rear, without trying the bike out since I saw sag adjustment more as "there is a predefined number you should aim for" compared to damper tuning which has to be tested back and forth until you find the optimum.

I then went about setting the dampers. I found a nice stretch of curvy road with medium long sweeping corners and followed the tips from the "Ohlins Suspension Setting" thread where I started by dialing back the dampers to their softest setting and working my way up from there, rebound then compression, rear to front. I ended up with the following:

FRONT:
Rider sag: 48mm
Rebound: 15 clicks
Compression: 22 clicks

REAR:
Rider sag: 33mm
Rebound: 18 clicks
Compression: 16 clicks

The problem is that I have a hard time telling what it is I should be "looking for" when trying the different settings. I mostly just thought "okay, I feel more confident now than before and the bike is doing more what I want it to do" until I ended up with this setting which I must say feels pretty good. With that in mind, I think "trying out" different sag settings would be even harder for me to distinguish the differences...
 
#4 ·
Ok so you went straight into it :grin2: It is very important to get your SAG set up 1st as this is your Starting point from where you them start playing with Compression and dampening.
If your SAG is not correct for you these are some of the effects. Your bike Falls too quick into corners.Your bike runs wide into corners. Your bike dips when braking moving your weight forward.Your bikes front wheel lifts too easy when accelerating. Your bikes rear tyre sags under when accelerating out of corners.
When your bike has a correct SAG set it will glide through corners sticking to the line you set it. It will feel light and fluid etc..... there is a huge difference in having it right. before you start Compression and Dampening.
The way I adjust REB & DAMP is to think of it like this if you SLOW the UP and DOWN motion of your spring you will get more Feel for the road therefore if your adjusting the REB & COMP so that it moves quicker it will feel softer and if you slow the REB & COMP speed it will feel stiffer,... stiffer gives better feel of the road in sport, Race and Twisties and therefore gives more confidance. When I ride the twisties in my sport setting I go much quicker than when I use my touring settings. BY the WAY (as John quite correctly pointed out to me a while ago when I was experimenting) you will find that you will only have between 2 - 4 clicks between Touring setting and sport setting........ I think you should figure out why your not getting ideal SAG.
 
#5 · (Edited)
When your bike has a correct SAG set it will glide through corners sticking to the line you set it. It will feel light and fluid etc..... there is a huge difference in having it right. before you start Compression and Dampening.
But if the dampers are set to their softest setting I have a hard time seeing that the bike will glide through corners and feel light and fluid the way you describe it, even if the SAG is spot on. No? Because as you say SAG should be set first, but then what settings should the dampers be on as a "default" or "reference point"? Bit of a catch-22 situation...
 
#6 ·
After SAG set up you must start from the standard Default settings (which would be Ohlin's standard settings) and then proceed as per Ohlins instructions as you did before. There is a technique most experts use which is to bounce the bike in a standing position and watch how it dips and springs back. What I know for sure is that if you are not at a satisfactory start point then you can click away in any direction and it wont seem to make any difference its just going to be different but always wrong. I know you think its a catch 22 situation but its not. if you return the COMP & DAMP (Front and Back) back to Default. Then address your SAG I guarantee your bike will be better than it is now (When your bike has a correct SAG set it will glide through corners sticking to the line you set it. It will feel light and fluid etc..... there is a huge difference in having it right. before you start Compression and Dampening.)
 
#11 · (Edited)
Lots of good tips! Thanks all!

After SAG set up you must start from the standard Default settings (which would be Ohlin's standard settings) and then proceed as per Ohlins instructions as you did before.
Would you then say that I should first set SAG according to your suggested 25-30% (with comp/reb @ default) and then tune SAG from there before starting on comp/reb? If so, this would require me to set front preload to maximum, and even then I would only achieve 33% front SAG.

psyopper said:
If the front were at 20% and the rear at 40% (a pretty extreme difference to show the point), then it would be said to be front biased, or titled forward. Balancing front/rear is important because an out of level bike changes other critical aspects of the suspension geometry, specifically fork rake and trail, which will also alter handling.
Did you perhaps write the SAG percentages opposite of what you meant? If the relative front SAG is less than the rear, this means that the bike is tilted backwards, no?

And again, it seems as if it would be impossible to balance front/rear SAG on this bike as the front spring is so soft, at least for track use. As I mentioned earlier the least amount if sag I can achieve in the front is 43mm = 33%. Since the front SAG is then limiting, what should the least amount of rear SAG be if I am to keep front/rear balanced? Also it doesn't feel optimal to set maximum preload on the front springs just to get inside of the ball park of what the front SAG should be. Poor front spring choice by Ducati? Again, I only weigh 61kg.

theresanothersteve said:
Make a record of all your changes. I use a spreadsheet so I can see previous settings at a glance, but I'm a little bit OCD.
Fellow OCDer here! :grin2: I've made recordings, albeit pretty messy. But I will go for a second round after the suggestions I've gotten here and will be more thurough.
 

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#14 ·
Did you perhaps write the SAG percentages opposite of what you meant? If the relative front SAG is less than the rear, this means that the bike is tilted backwards, no?
I did, my apoligies. But it seems like you understand the principles pretty well based on your correction. :)

I work night shifts and had a pretty strong margarita while I was writing that. I was pretty blasted by the time I got to the end. You should see how many times I had to restart some of those sentences.:p

On some videos it was said that front static sag should be about 30mm. Could anyone tell me this figure in percentage of total wheel travel?
Was that a specific Supersport video? A lot of those videos are aimed at track bikes, which commonly limit travel to 120mm front and rear. Being a sport-touring oriented motorcycle, Ducat gave us more travel, and then even more travel in the rear. This is also why we talk about percentages rather than static numbers.

Front travel is 130mm ... Rear Travel is 144mm
This is where the math comes in. 30 is what % of 130? 30/130=0.23 == 23%

As for spring choices, again Ducati built this to be a sport-touring bike with more compliance up front and more capacity (for baggage and/or passenger) in the rear. The bike is really sprung for about 300 lbs of rider/baggage weight in the rear. Big heavier guys like me (230 lbs) are close enough to the intended capacity that we don't need to respring. Lighter riders who ride without passengers may want to find a lighter rear spring.

I enjoy the slightly plusher ride from the lighter front springs. It might slow the bike down slightly, but when I was first learning performance driving I had an instructor drill into me the mantra "slow is smooth and smooth is fast." Part of that was driving an underpowered Miata, where carrying corner speed is really important because you don't have the spare HP to correct on the corner exit. I really do ride faster because of it. I also think this is the same mental change that Dovi went through last year when he talks about reorienting his mentality to his racing. He's is much smoother and more fluid than many of the other riders, and rides much more zen like.
 
#15 ·
I work night shifts and had a pretty strong margarita while I was writing that. I was pretty blasted by the time I got to the end. You should see how many times I had to restart some of those sentences.:p

Was that a specific Supersport video? A lot of those videos are aimed at track bikes, which commonly limit travel to 120mm front and rear. Being a sport-touring oriented motorcycle, Ducat gave us more travel, and then even more travel in the rear. This is also why we talk about percentages rather than static numbers.
Haha if you were blasted I must say I'm pretty impressed with how thorough and descriptive you were in your post! :D

It was not a specific Supersport video, more a general video on how to set sag. Which is why I'm looking for static sag percentage on a sporty tourer rather than the static numbers given.

It's clear to me now that I need to reduce the preload on my rear spring but my question still remains on the importance of front/rear sag ratio. As previously mentioned I cannot achieve a front sag less than 33% (unfortunate for track riding I guess?) but should I then not go below 33% sag in the rear as well? Should one always strive to have the same percentage sag front and rear?
 
#7 ·
Maybe it would help you visualize what you're doing for yourself with sag adjustments. There are two directions that the suspension travels, up and down - or compression and extension respectively, and you want your suspension to hover somewhere in the middle of the two extremes of these. The idea is that road irregularities are of two types - protrusions and depressions. When you roll over a protrusion you need your suspension to compress to absorb the difference and give you a controlled ride; conversely, when you encounter a pot-hole (depression) you need your suspension to extend into the irregularity without upsetting the bike balance. Setting sag gives you this extension.

When you set your sag you are setting a value of how much extension and compression you have available when the bike is flat and level, and are defining the percentage at which the suspension can travel either way. So, when you set the sag to 30% you are pre-compressing the spring 30% of the shock's stroke to give you that number in extension. If you were setting up a track bike, you might set your sag to 15%-20% because tracks are relatively flat smooth surfaces, setting up a sport bike for road use might be more like 20%-35%, and a cruiser might be set with even more sag than that. The number you select is based on the frequency and size/shape/depth of your extending road irregularities and personal comfort in negotiating them. In other words - it depends. Start with 30% and go from there.

Because our bikes have more suspension travel in the rear than the front the sag numbers are considered level by measuring their percentage of total stroke. If both front and rear are at 30% then the bike would be considered "level." If the front were at 20% and the rear at 40% (a pretty extreme difference to show the point), then it would be said to be front biased, or titled forward. Balancing front/rear is important because an out of level bike changes other critical aspects of the suspension geometry, specifically fork rake and trail, which will also alter handling.

If your roads are rough, start with your sag set to about 35% at both front and rear (so that you have compressed 35% of the free length of travel) to give that much travel available in suspension extension into negative road irregularities. This would be best in cold weather states that often have frost heaved roads, large potholes, etc. If you live in Southern California and have glass smooth roads, you might reserve less sag and opt for 25% (or even less).
 
#8 · (Edited)
My take on this is yes if you like playing as much as riding that's Good, but sometimes one can over analyse things


What I have always done over the past 50 years is ride the bike with the factory settings first, put it through its paces in the corners etc, if it feels good leave it alone, if you are not happy & it does not feel right then look at adjustments that might suit better.. however if you are planning lots of track days on a nice smooth circuit then you may want to tweak it a tad..
I am 6ft approx' 99 kg with all the gear on, My Thruxton R has the Ohlins front & rear & the factory settings are more than adequate & I do like to ride hard & fast.
My Ducati SSS has finally arrived at my dealership so it will be on the road quite soon [that's when they have fitted the extras]
if I decide the suspension needs any adjustment I wont touch it until i have put some miles on it & given the factory setting a chance.
 
#9 ·
Some advice (take it or ignore it as you will)...

Make a record of all your changes. I use a spreadsheet so I can see previous settings at a glance, but I'm a little bit OCD.

Set sag first, front and rear. Then look at fork rebound, then fork compression. Then shock rebound and then shock compression. Make one small change at a time, ride and evaluate.

I must admit the first thing I did after setting sag was a major front compression change, but mine was way out. Then I did the slowly, slowly approach (and I'm still fine tuning).

I posted some figures that Radskills used on my bike for initial setup, but I find I'm fine tuning back towards the figures Rhino posted.

One of the suspension tuning books I've been reading suggests there is a maximum feel setting, and a maximum traction setting (usually closer to a comfort setting). What you are trying to do is set your suspension between these settings.
 
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#12 · (Edited)
Ok:grin2: lets get on the same page. you should have 3 measurements 1st measurement is called FREE SAG (when your bike is lifted off the ground allowing your spring to full extend.) 2nd measurement is called STATIC SAG ( This is when your bike is standing on its own) 3rd is called RIDER SAG ( With the rider fully kitted in a riding position ) So It stands to reason that your FREE SAG measurement should always be the same.. Yes. This is also the Same with your STATIC SAG as the bike is still the same weight (unless you have added fuel or attached something to the bike) Yes. RIDER SAG can change if you move your position forward or back etc and this is why we measure 3 times to be sure. the only reason I say this is that the measurements you have written down have changed. I cant see how your not achieving SAG in the front because you should be able to so something is wrong somewhere. Can you do me a favour and Put the Bike back to stock Preload and take your measurements. Then back the rear preload off completely (the rear is quite hard) Then take measurements (this should naturally lift the Front.) Then back the preload off from all the way in to half way out and take your measurements. those 3 measurements should build a picture of what is happening. (If you look at your rear measurements it is showing that the rear of your bike is way too high)
 
#13 · (Edited)
Then back the preload off from all the way in to half way out and take your measurements. those 3 measurements should build a picture of what is happening. (If you look at your rear measurements it is showing that the rear of your bike is way too high)
How do I know what "all the way in" is? Is there a maximum? I figured it depends on how long the handle of your c-spanner is/how strong you are :p During these three measurements I should keep the front preload in stock setting?

On some videos it was said that front static sag should be about 30mm. Could anyone tell me this figure in percentage of total wheel travel?
 
#19 ·
Karish, like you, I can only get to 43mm rider sag in the front at maximum preload. I’d like to have 35-39mm. So really I could use stiffer front springs. But despite the less than ideal sag, it actually handles nicely. So I’m okay with it until (and if) I get around to swapping out the springs. Don’t worry about being at maximum preload, as the adjustment range is somewhat arbitrary and even at max settings still allows the springs to work fully. I see Rhino answered your other questions accurately. So you’re in good shape.
 
#21 ·
I just watched this from Dave moss the most interesting point was when he measures the front and winds the preload all the way in. It changes his start measurement from 0mm to 6mm. not that it maters in the end when you have reached your SAG numbers and re check but interesting to see how it makes the difference. Dave is the Man... he knows his stuff:grin2:
 
#25 ·
So, regarding static sag. In the rear, I get absolutely no static sag. Measurement is the same when bike is on both two wheels and when rear wheel is off the ground. I know the shock spring is massive at 105N/mm and the SS tail is really tiny/light, but I haven’t seen such behaviour on other bikes. I bought the bike second hand, so probably previous owner has fiddled a bit with suspension settings, just trying to find out what’s normal. At this heavy preload, I still got 30 mm of rider sag (measured from forward edge of rear indicator to the inside top of the wheel axle).

I did unload the preload ring on the shock a bit, and still got the same rider sag (30 mm), but a few mm:s of static sag. Seemed a bit funky, but maybe that’s how it is with this massive spring? To get to the Öhlins app suggested sag of 28 mm, i should in fact have increased, rather than decreased preload but then it’d have been superstiff?

Front rider sag was 55 mm when I got it (30 mm static sag), but I set it to 45(ish) mm rider sag, per the Öhlins app. Just to be clear, the figure for rider sag includes the static sag, correct? That is, I shouldn’t add the suggested 46 mm to the 30 mm of static sag, that’d be way to much (half the suspension travel), correct?
 
#34 ·
One thing I noticed reading thought this thread is conflicting meaning given to terminology. And that can be found in just about any discussion on 'sag'. The same term being used to describe different things, especially the term 'static sag'.

To me the terms are ...

Suspension travel .... its just called that.
Free Sag ..... the amount just the weight of the bike alone compresses the suspension
Race, Rider, Static Sag ........ all mean the exact same thing. The amount the combined weight of the bike and rider compress the suspension

Now I'm sure the above is not going to straighten out the whole world's use of the terms, so just be aware of this problem when reading any article on the topic. Some 'interpretation' of terms being used is often necessary.
 
#36 ·
I’m going to leave my last response, though this clears some things up. Where some of my confusion sits is in my experience, free sag and static sage are interchangeable, rider sag is the rider sag plus free sag.
 
#42 · (Edited)
I just checked the spring, and it’s the stock 105 N/mm one. I asked this same question on another forum and was so fortunate to get a reply from someone who works for Öhlins at their race department in Sweden (supposedly he’s been consulted during the development of the SS. According to him, normally no static sag would indicate a too soft spring. However, the shock in the SSS doesn’t have a top out spring, which with a stock spring rate that’s on the heavier side for my weight (80 kg in the flesh) can give the behaviour I mentioned. That is, no static sag when correct rider sag has been set doesn’t have to be an anomaly in this case.

John, which spring do you have? Stock? No issues getting reasonable sag?
 
#45 ·
Sure the Ohlins rep didn't say the shock has a top out spring? I wouldn't have expected it would. A heavy or long top out spring can influence sag numbers in a shock or forks.

Me, I don't even own an SS. I joined the forum when the bike was first announced, and just look in from time to time, contributing to 'generic' discussions if I think I can contribute. That's usually just suspensions as they all work pretty much the same (other than semi active, etc,) on any bike.
 
#48 ·
Anyone wanting to learn more than the basics of how to adjust their suspension, or to even better understand just the basics, I highly recommend the following series of videos. They are now a couple year old, but the information is as relevant as ever.

They are in my mind by far the most informative series of videos that I know, narrated by an obviously high-knowledgeable expert (the owner of Traxxion Dynamics).

There are 20 videos in the series, with each 'Chapter' clearly marked and easily found with a Google search. Sometimes the next in the series will load in the correct order, but often it will jump way ahead, so just be aware that at the end of each one check that the next is the correct one, as you may need to exit and manually find the next in the sequence.

https://www.youtube.com/watch?time_continue=403&v=ywkzj1x4YE8
 
#49 ·
Chapter 13 (link below) is the most relevant to this topic. I should highlight I've never previously watch it as someone would easily believe I've just been regurgitating the video in previous posts, so similar is the video.

Truly never watch it before. If I had I would have just posted a link to it and said ....'watch this' instead of doing all that typing.


 
#50 ·
Well, I’m at just over 2000 km on my 950S but haven’t gotten around to setting sag properly just yet. I was feeling quite ok with the settings as they were from the dealer but now after setting comp/rebound to default settings front and rear and setting front sag to about 30%, the difference is quite noticeable! It was feeling a bit wallowy before but much more planted now. That is, I exaggerated sag and on the rear, because I wanted to se what it felt like, so currently at around 25% rear sag. Although I like the front heavy stance for the increased agility, I think that was way too much.

now, some of the difference is surely because I turned down traction control and abs a notch each, to be less intrusive, but I did feel I was pushing the front too much in my favourite highway on-ramp (a tight right corner opening up towards the entrance onto the highway itself). Previously it was planted through out. I also had more noticeable feelings of the rear stepping out on corner exit but surely that is mostly because I lowered DTC sensitivity (I know I know, stick to one change at a time). I should probably dial it back up to default setting to get a proper idea of what effect the adjusted sag really had on the bike.

anyway, set your sag and double check the suspension settings, folks. May have a bigger impact on your driving than what you think!
 
#51 ·
This is an interesting thread. I think for the most part good information is contained here however Sag % figures are just a general starting point. Same as the comp/rebound settings. Balancing the front and rear suspension together is most important.
 
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