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IanC

Cannot set sag on rear?

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D.A.

I’ve come across a lot of contradictory info on the internet — some of which seems rather dubious — regarding how to measure static sag. Which technique are you using to measure yours?

Edited by D.A.

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IanC

So here is how i'm doing it:

Start with bike level on the ground...

  • For the front
    • Give the suspension a few bounces and let it return naturally.
    • Mark the position of fork (I use a zip tie).
    • Lift up the front at the triple clamp and measure - this is what I have been calling static sag, and targeting ~10mm.
    • Get on the bike, either with someone holding it or in my case I used a front wheel chock. Mark the fork, get off and measure distance from static position. This is what I've been calling rider sag, and targeting ~25mm.
    • I've also done the above by myself by attaching a steel rule to the fork, and then recording the above and reviewing the video.
  • For the rear
    • Bounce and let return.
    • Hold rule to measure a fixed part of the rear from the ground.
    • Repeat as above, lift up rear to get static, get on for rider. Targeting the same values as up front.

Ian.

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IanC

As an aside I made some changes to the front as recommended in this DMT video yesterday and am really happy with the result.

The forks seem to behave much better with the thicker oil, and the nose dive is reduced quite a bit!

Ian.

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cornerslider
22 hours ago, mossrider said:

So here's my 2 cents. Granted I'm not a suspension guru or even knowledgeable for that matter but I have spent countless hours fooling with suspension. 

No one in the history of motorcycling has ever riden their bike w/o being on it. What I mean is static sag is great in a perfect world but it's not the end-all. If you have zero static sag but can get around an inch and a half or so rider sag you're in the ball park. If you can't get enough rider sag then your spring is too stiff. 

It's that simple in basic terms.

Now, having said that: You do need a fair amount of sag for the suspension to function properly, to keep the tires in contact with the road surface, to give a comfortable ride and to let the motorcycle perform well over rough terrain and on the brakes/gas.  As to your mention of "pogo". Pogo is more a result of uncontrolled or poorly damped suspension than it is related to sag. (assuming both ends have the proper spring rate) If the front forks have proper compression damping they don't over-dive on the brakes. In like fashion if the rear shock has proper rebound damping it doesn't over-rise on the brakes. The converse is true on the gas; rebound on the front, compression on the rear. A properly set up suspension will work in unison, feel settled and composed over rough ground, feel like it squats rather than pitch or rock when hard on the brakes and rise not rock on the gas. The bike will also handle better, hold a line in corners, change direction easilly to avoid hazards and tighten or relax it's line in turns effortlessly and w/o drama. 

I don't know if any of this makes sense but there it is.

BLR

 

@mossrider and I use the same suspension tuner.....  I'm gonna try to convey what I learned from hiring an experienced tuner that doesn't do "YouTube" videos to scare half the FZ/MT-07 riders into cutting 10mm out of a spacer, and expecting a miracle....  I tried the "do-it-myself" method after upgrading my suspension (front & rear). After a couple years, I learned that trading my money for knowledge was a MUCH better option..... I was obsessed with "static sag/sag" numbers, and nearly lost my mind chasing it. I got to the point of what I refer to as "analysis-paralysis", too much data/information. I then hired a well respected/local suspension tuner. I told him what I had done with trying set static sag/sag numbers, and he stopped me.... Then he asked me "When was the last time you rode your bike without being on it?" I didn't understand the question? He then suggested I get the proper rate springs for my weight (front & rear), and not obsess about "sag" numbers. Get the right springs for your given weight, and find what works your YOU.... As it turns out, I like more rebound dampening than most people. Does that make me "faster" than anyone else on the track- absolutely NOTl!!! My personal set-up increases my rear tire wear slightly- I don't care... I was fortunate enough to learn what worked, and felt  right to me. Another person of my same weight could easily ride my bike and absolutely HATE my suspension set-up... I don't want to sound condescending to anyone trying to tune the OEM suspension on their bike. That being said, the OEM suspension is very limited of our beloved bikes. I'm not suggesting that you need to spend thousands of dollars in upgrades to your suspension. You can do it on a budget. I recently upgraded the suspension (front & rear) on my "street" 2019 Yamaha R3 for $750. Those same components are available for the FZ/MT-07. I'd assume the result would be about the same-

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""W.O.T. until you see god, then brake"

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rfmueller

It seems like it is a matter of personal taste and what works for you.  I love the suspension on my FZ.  According to the so-called standard, I have the tension set too tightly for cruising, but it feels great to ride it.  I'm 155 pounds + gear, and have the tightening gear set on smack in the middle, (whatever step that is).  It only sags about 28mm total, including no-load sag.  The sitting position is wonderful on the back, and I enjoy feeling the road.  And, when loaded up with road trip gear, there's no need for more tightening.

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IanC
13 hours ago, cornerslider said:

@mossrider and I use the same suspension tuner.....  I'm gonna try to convey what I learned from hiring an experienced tuner that doesn't do "YouTube" videos to scare half the FZ/MT-07 riders into cutting 10mm out of a spacer, and expecting a miracle....  I tried the "do-it-myself" method after upgrading my suspension (front & rear). After a couple years, I learned that trading my money for knowledge was a MUCH better option..... I was obsessed with "static sag/sag" numbers, and nearly lost my mind chasing it. I got to the point of what I refer to as "analysis-paralysis", too much data/information. I then hired a well respected/local suspension tuner. I told him what I had done with trying set static sag/sag numbers, and he stopped me.... Then he asked me "When was the last time you rode your bike without being on it?" I didn't understand the question? He then suggested I get the proper rate springs for my weight (front & rear), and not obsess about "sag" numbers. Get the right springs for your given weight, and find what works your YOU.... As it turns out, I like more rebound dampening than most people. Does that make me "faster" than anyone else on the track- absolutely NOTl!!! My personal set-up increases my rear tire wear slightly- I don't care... I was fortunate enough to learn what worked, and felt  right to me. Another person of my same weight could easily ride my bike and absolutely HATE my suspension set-up... I don't want to sound condescending to anyone trying to tune the OEM suspension on their bike. That being said, the OEM suspension is very limited of our beloved bikes. I'm not suggesting that you need to spend thousands of dollars in upgrades to your suspension. You can do it on a budget. I recently upgraded the suspension (front & rear) on my "street" 2019 Yamaha R3 for $750. Those same components are available for the FZ/MT-07. I'd assume the result would be about the same-

Absolutely agree there is no substitute for an actually human that knows what they are doing advise.

No one should be scared into doing anything. I chose to do what I saw there as it is a $0, fully reversible change, and more than anything just gives me an excuse to spend some time tinkering with my bike. However, I probably should not have posted that here and instead in its own topic as it was an aside to why I started this topic.

 

I phrased the initial topic as "can't get static sag", only because thats what I believe to be the issue - I agree with you the most important thing is not the sag numbers, but how the bike feels...and mine doesn't feel great in certain situations. I still believe this is due to the rear having no free play above it's resting position - each time the suspension rebound on a bump or hump in the road it rebounds onto a hard and abrupt stop - I assume right now this can be cured by adding some amount of static sag/free play at the top of the shock's stroke. Even a millimeter would be welcome, at the very least so that I could ride the bike and verify if that is actually the issue. 

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IanC
11 hours ago, rfmueller said:

It seems like it is a matter of personal taste and what works for you.  I love the suspension on my FZ.  According to the so-called standard, I have the tension set too tightly for cruising, but it feels great to ride it.  I'm 155 pounds + gear, and have the tightening gear set on smack in the middle, (whatever step that is).  It only sags about 28mm total, including no-load sag.  The sitting position is wonderful on the back, and I enjoy feeling the road.  And, when loaded up with road trip gear, there's no need for more tightening.

Seems like your experience is similar to others.

In my case, i'm 190lbs + gear, and even with the preload adjuster at at minimum the shock is way to stiff, and sags less than yours. Maybe Yamaha ran out of springs that day and used one from a Ford F350?

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Yakko Warner

I finally got around to measuring my sag.  I'm 180lbs and wore street clothes.  My 2018 MT-07 was in a front wheel chock, so the front wheel was off the ground a bit.  After minimizing preload, I got 2-3mm free sag, and 30mm rider sag.  My front end was even more oversprung.

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le druide
13 hours ago, Yakko Warner said:

I finally got around to measuring my sag.  I'm 180lbs and wore street clothes.  My 2018 MT-07 was in a front wheel chock, so the front wheel was off the ground a bit.  After minimizing preload, I got 2-3mm free sag, and 30mm rider sag.  My front end was even more oversprung.

Are you happy with this zero preload set up on the road ? 

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IanC
18 hours ago, Yakko Warner said:

I finally got around to measuring my sag.  I'm 180lbs and wore street clothes.  My 2018 MT-07 was in a front wheel chock, so the front wheel was off the ground a bit.  After minimizing preload, I got 2-3mm free sag, and 30mm rider sag.  My front end was even more oversprung.

Sounds like maybe its common to the 2018 platform...maybe they got tired of having everyone complain about the 'soft' suspension and decided to go in the exact opposite direction.

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Yakko Warner
8 hours ago, le druide said:

Are you happy with this zero preload set up on the road ? 

I'm in California, sheltering in place, so unfortunately riding my motorcycle would be nonessential travel, which is prohibited.  So I haven't ridden it.  But I expect it to be a little better.  The preload was originally in the middle at "4", where I got 0 free sag and 26mm rider sag.  The ride was harsh on bumpy roads before.  So minimizing preload to get an additional 7mm sag will likely make some improvement.  We'll see.

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le druide
3 minutes ago, Yakko Warner said:

I'm in California, sheltering in place, so unfortunately riding my motorcycle would be nonessential travel, which is prohibited.  So I haven't ridden it.  But I expect it to be a little better.  The preload was originally in the middle at "4", where I got 0 free sag and 26mm rider sag.  The ride was harsh on bumpy roads before.  So minimizing preload to get an additional 7mm sag will likely make some improvement.  We'll see.

I think the ride will be softer at zero preload and less harsh on bump.

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Bigturbomax
On 4/2/2020 at 12:37 PM, le druide said:

Ok so it's the OEM spring , I think the rate for 2018 and up is in the 625 lb/in range , I don't think it's defective, just too stiff, maybe other 200 lb rider can share sag values to compare.

To my research rear shock spring rate on 2015 to 2017 models is 625lbs/in and i found 2 unverified magazine reviews for the 2018+ model rear spring being 11% stiffer. Which would mean the 2018+ rear spring is in the range of 693lbs/in. 

All that having been said i put a 2018 rear shock on my 2017 model. I am 205 lbs WITHOUT gear and on the 2nd preload notch i have 32.7 mm rider sag in the rear. I believe my static sag was only around 5mm if i remember correctly. 

Im actually considering swapping my 2017 spring onto my 2018 shock as the 2018 shock has WAY better valving but i think its oversprung a bit. 

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le druide

Wow near 700 lb/in that's pretty stiff !  This is why I replaced the OEM spring with a softer one, the  rear sag with me on the bike was only 10 mm with the OEM spring, ok I'm not the heaviest guy at 135 lbs with gear so I put  a 475 lb/in spring and the sag is now 30 mm and static sag is 2 or 3 mm only

maybe a 450 or 425 lb /in spring would give a 35 -40 mm ?

 

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maz20
On 4/3/2020 at 8:07 PM, IanC said:

Which is certainly happening with my bike. 

I let a friend of mine with an R3 ride it and he had the same criticism without being prompted. He mentioned he felt like he was being launched out of the seat...which I'd agree with!

So if increasing rebound over what would be considered ideal is not helpful, and sag doesn't exist even at the lowest available preload setting, then I guess that just how it is (unless it is mechanically binding/stuck/defective) as mentioned above.

I'm going to look again in the morning, but I've stared at that thing long enough that I should have noticed a mechanical issue with the spring.

Ian.

If you're experiencing "fling-off" symptoms then it's time to "roughen-up" the rear shock (as I like to say). In other words, increase your compression damping. Preferably, with an aftermarket shock with adjustable compression damping.

Generally speaking, for any shock to absorb a given amount of "bump energy" within some distance (your compression travel, that is!), you usually only have two options:

  1. Use a stiffer spring with less compression damping -- you will get less "hit" but more "fling". For example, running over a speed bump quickly in this scenario will feel "smooth" (which is nice!) but will also fling you off more (not so nice!). Generally speaking, small bumps might feel nicer, but big bumps will give you much more of a "fling"!
  2. Use a softer spring, but with more compression damping -- you will get more of a "hit", but less of a "fling". So, in this scenario, for example, running a speed bump quickly will just give you a little more initial "hit" (just from encountering the bump), but will not fling you off as much.

Note that the heavier the rider and stiffer the spring, the more "baseline damping" (i.e., the 'middle point' in the range of damping adjustment for the compression/rebound clickers/adjusters) has to be built into the shock. Yes, there is a "range" of adjustment, but even that whole "range" can often be way too narrow -- so once again that's why the best is an aftermarket shock built to your weight range and your riding preferences. Most aftermarket shock manufacturers should be able to build one for you based on the weights & preferences you specify through their online order forms.

P.S: with respect to the "pogo"-effect you brought up, that's most likely (as others have mentioned) due to too little rebound damping. The stock shock is not adjustable for rebound damping, so that's another reason to get that aftermarket one!

Edited by maz20
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IanC
20 hours ago, maz20 said:

If you're experiencing "fling-off" symptoms then it's time to "roughen-up" the rear shock (as I like to say). In other words, increase your compression damping. Preferably, with an aftermarket shock with adjustable compression damping.

Generally speaking, for any shock to absorb a given amount of "bump energy" within some distance (your compression travel, that is!), you usually only have two options:

  1. Use a stiffer spring with less compression damping -- you will get less "hit" but more "fling". For example, running over a speed bump quickly in this scenario will feel "smooth" (which is nice!) but will also fling you off more (not so nice!). Generally speaking, small bumps might feel nicer, but big bumps will give you much more of a "fling"!
  2. Use a softer spring, but with more compression damping -- you will get more of a "hit", but less of a "fling". So, in this scenario, for example, running a speed bump quickly will just give you a little more initial "hit" (just from encountering the bump), but will not fling you off as much.

Note that the heavier the rider and stiffer the spring, the more "baseline damping" (i.e., the 'middle point' in the range of damping adjustment for the compression/rebound clickers/adjusters) has to be built into the shock. Yes, there is a "range" of adjustment, but even that whole "range" can often be way too narrow -- so once again that's why the best is an aftermarket shock built to your weight range and your riding preferences. Most aftermarket shock manufacturers should be able to build one for you based on the weights & preferences you specify through their online order forms.

P.S: with respect to the "pogo"-effect you brought up, that's most likely (as others have mentioned) due to too little rebound damping. The stock shock is not adjustable for rebound damping, so that's another reason to get that aftermarket one!

Agreed - At least with the front forks I could tinker... with the back I suppose my only option is to replace. I suppose I could try a softer spring if I can find one for a reasonable price, however at that point should probably pony up for a whole shock with compression damping.

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stickshift
On 4/22/2020 at 1:40 AM, IanC said:

Sounds like maybe its common to the 2018 platform...maybe they got tired of having everyone complain about the 'soft' suspension and decided to go in the exact opposite direction.

The stock suspension is not soft at all, front and rear spring rates are right in the ballpark for average rider weights. It's the lack of damping that magnifies all the issues.

Throw a quality aftermarket shock and cartridges on (with same spring rates as stock) and it's a much different beast.

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thetyrant

Old thread resurrection!

Just found this thread when searching about rear sag on the MT07, i have recently acquired a low mileage 2019 mt07 so guessing same suspension s the OP's 2018, likewise i have rear preload on lowest notch and zero static sag and while overall i feel rear suspension isnt too bad i do on occasion get bucked out the seat as damper tops out, so i feel rear spring is just a touch too hard for my weight which is around 80kg/170lbs.

 

Interesting with a slightly lighter weight passenger on back and no adjustment suspension is very plush feeling, bit on soft side  but not bad for 2 up riding and could up preload and damping to help with that.

 

Anyhows im wondering if fitting a earlier pre-2017 rear spring is worth trying as read they are approx 10% softer, has anyone tried this ?

 

Thanks

 

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Julian
22 hours ago, thetyrant said:

Old thread resurrection!

Just found this thread when searching about rear sag on the MT07, i have recently acquired a low mileage 2019 mt07 so guessing same suspension s the OP's 2018, likewise i have rear preload on lowest notch and zero static sag and while overall i feel rear suspension isnt too bad i do on occasion get bucked out the seat as damper tops out, so i feel rear spring is just a touch too hard for my weight which is around 80kg/170lbs.

 

Interesting with a slightly lighter weight passenger on back and no adjustment suspension is very plush feeling, bit on soft side  but not bad for 2 up riding and could up preload and damping to help with that.

 

Anyhows im wondering if fitting a earlier pre-2017 rear spring is worth trying as read they are approx 10% softer, has anyone tried this ?

 

Thanks

 

It's virtually impossible to have 0 static sag. You may not have a lot but you will always have some. Most likely you are not measuring it correctly or you are referring to something else. If you post the steps you are taking I can check. 

In the meantime have a look at my post with my settings. 

 

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thetyrant
45 minutes ago, Julian said:

It's virtually impossible to have 0 static sag. You may not have a lot but you will always have some. Most likely you are not measuring it correctly or you are referring to something else. If you post the steps you are taking I can check. 

In the meantime have a look at my post with my settings. 

.

Thanks for your input, by zero static sag i mean when  hold the bike upright at the back and bounce the suspension then let it settle it tops right out and cant lift it up any at rear, well maybe a tiny bit 1mm say but not really measurable, i would say its right at the top of its travel until i sit on the bike.

 

Its only just at the top and not like it slams up to it as i have the damping set to allow it to rise smoothly but Im going to add a little more rebound and see how that feels, ive read others have done similar and its improved the kick out the seat problem, just dont want too much damping to give other issues keeping tyre on ground etc.

Edited by thetyrant

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Julian
4 minutes ago, thetyrant said:

Thanks for your input, by zero static sag i mean when  hold the bike upright at the back and bounce the suspension then let it settle it tops right out and cant lift it up any at rear, well maybe a tiny bit 1mm say but not really measurable, i would say its right at the top of its travel until i sit on the bike.

 

Its only just at the top and not like it slams up to it as i have the damping set to allow it to rise smoothly but Im going to add a little more rebound and see how that feels, ive read others have done similar and its improved the kick out the seat problem, just dont want too much damping to give other issues keeping tyre on ground etc.

As I suspected, you are likely talking about damping not sag. They are two different things and the measurements and settings are independendt from one another.

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thetyrant

Im talking about how much the bike sags on the springs under its own weight with no rider on and held upright, so to me thats static sag?.

Damping of course is a factor  and ive always been taught to set the rebound damping so that when you press the rear down and release its just got enough damping so its not springing up fast, starting with it at minimal so you can see it move fast... which on this bike was fast! then adjust until its rising smoothly and i have it like this now but maybe it will benefit from a touch more.

 

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M. Hausknecht

Yes, what is meant by "static sag" is the amount of sag, front or rear, without a rider on board. Its easy to set up a bike without any static sag by adding preload or a combination of a stiffer spring and some preload to that spring. As a practical matter, it is the addition of preload which eliminates static sag, since a stiffer spring without installed preload will always sag at least a little bit under the weight of the bike.

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Julian
36 minutes ago, thetyrant said:

Im talking about how much the bike sags on the springs under its own weight with no rider on and held upright, so to me thats static sag?.

Damping of course is a factor  and ive always been taught to set the rebound damping so that when you press the rear down and release its just got enough damping so its not springing up fast, starting with it at minimal so you can see it move fast... which on this bike was fast! then adjust until its rising smoothly and i have it like this now but maybe it will benefit from a touch more.

 

For sag you need 3 measurements, A B and C. The measurements should always be taken between the same two points, one being the rear axle and the other one a fixed point on the tail of the bike directly above the rear axle. You can put a piece of tape on the tail to make sure you are measuring to the same point, and the same person should take the 3 measurements for consistency.

For measurement A you need to grab the bike under the tail or from the pillion pegs and lift it until the rear tyre is in the air and there is no weight on it at all. You need two people to lift the bike and a third one to measure, unless you are very strong. 

Measurement B is done between the same points with the rear wheel on the ground and the bike unsupported.

Measurement C is done between the same points with the rider on the bike in the normal riding position and the feet on the pegs.

A-B is your static or free sag, and it will not be 0 because the bike does not weigh 0 and the suspension is elastic. 

A-C is your rider sag. 

You are aiming for 5-10 mm free sag and 30-40 mm rider sag but on a street bike with stock suspension you will never get the ideal numbers that you see in the videos. I have 6-7mm free sag and 34 rider sag which is very acceptable.

Edited by Julian

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M. Hausknecht

Julian, all correct except for your assertion there cannot be zero static sag. To have zero static sag all you need is sufficient preload on the spring, such that the preload on the spring (for example, one inch of preload on a 7oo inch/lb spring, so 700 pounds) is a higher weight than the force placed on the spring by the unladen weight of the motorcycle (of course, because of linkages and the angles of the linkages and the spring assembly itself, the relationship between spring preload and load on a tire is not one-to-one). You are correct that a spring without installed preload will always collapse a bit when a load is placed on it; installed preload can reduce or eliminate that collapse (that is why we add preload to get the laden sag where we want it).  Finally, to get the correct static sag and the correct laden sag, you need the right spring(s) and preload.

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