Ninja H2 banner
1 - 20 of 35 Posts

·
Registered
Joined
·
836 Posts
Discussion Starter · #1 ·
After reading GoFasters thoughts on the H2 suspension I thought a new thread may help complete suspension idiots like myself .

Poorly handling bike have been the norm throughout my riding history as I started in 1980. Bucking and pitching
bendy bike frames have never phased me even when I was racing in the 350 LC headbanger class , subsequently when bikes became better equipped I was so used to bikes squirming around I have never really played with settings .

I find the H2 very harsh and probably would benefit from some tweaking but I don't know where to start . Can I have some basic advise on a good starting point ?
I am around 180-190 lbs and I ride on UK B roads only ( two lane back roads )
The roads are OK but a long way from racetrack smooth. Looking for a compliant smooth starting point .
Any advice is welcome and I won't be offended in you write it like you are talking to a suspension moron as that's exactly what I am .
 

·
Registered
Joined
·
503 Posts
Ah, the black art of suspension

First place to start is setting your suspension sag, there are two ways, static (bike weight only) and rider sag (with ya ass on it)

for road riding, static sag is ok, aim or 25 to 30mm front and 10 to 12mm rear, both set by adjusting pre-load

damping, compression is the rate/speed that the forks/shock compress, rebound is the rate/speed they return from compressing

A good starting guide basis is to set the damping 2/3 hard 1/3 soft and adjust from there

A key factor to correct damping is, when you compress the front (by pushing down on the front of the bike)they should return and drop down slightly on their own weight

I'm no expert but have set my own or road and track riding for years

This is a good site or basic information Motorcycle Suspension Set-up

Rob
 

·
Super Moderator
Joined
·
699 Posts
Oh boy. This is an exceptionally complicated topic. My perspective is from 25 years of regional-level roadracing on mostly tracks that are, ahem, a little short of international standards.

Here are your priorities. Always keep your priorities in order. There is a reason they are in this order. You can twiddle the clicker adjustments all you want but if the geometry is not right, it will never work right, and if the spring rates are wrong, it will never work right.

First, geometry (Rake, trail, swingarm down-angle i.e. swingarm pivot height, center of gravity height and wheelbase and weight distribution play into this). This affects how the bike responds to steering inputs and throttle inputs ... which are also partially steering inputs.

Then, springs (both preload and spring rates). This establishes where your suspension acts within its range of travel. You do not want it bottoming, and you want it to be in an operating range where it does not screw up the geometry.

Then, damping (low speed, high speed). "Speed" here refers to the speed of suspension movements. Bulk motions of the vehicle in pitch or rebound are low-speed motions. Small irregularities can be in the low-speed range as well but bump hits that you really feel are in the high-speed range.

If you can get a chance to read this book Suspension Bible do it. It explains this in far more depth than I ever could. But I will try ... in the next posts to tackle those priorities one by one.
 

·
Super Moderator
Joined
·
699 Posts
How geometry affects the bike. First, rake and trail.

"Rake" is the inclination angle of the steering axis from vertical. If you draw a line in 3-D space through the steering head bearings and project that down to ground level, it will reach ground level some distance ahead of the tire's contact patch. That distance is the "trail". These affect stability and they affect the amount of effort that it takes at the handlebars to change the bike's lean angle (i.e. initiate a turn). There is a balancing act between this geometry and the profile of the tires, because these also affect how much effort is required at the handlebars to KEEP the bike turning. I strive for "neutral" steering - after I have set a lean angle, "neutral" feeling feels like you could take your hands off the bars and the bike would stay at that lean angle, not straightening up, and not falling into the corner.

Rake and trail are both affected by ride height front and rear. If the front end is sitting up higher or the rear is lowered, it rakes out the front end and adds trail. The consequences will be higher effort to turn in, and if taken too far, it will require a constant effort to hold the bike at a certain lean angle - the bike will want to straighten up. If you go the other way, the bike will want to fall into the corner, and try to wash out the front end, which is unstable and is extremely unnerving. The balance - "neutral" steering - is a fine one. I adjust ride heights 2 mm at a time in order to achieve this.

Tire profiles play into this. If your tires are worn in the middle due to too much riding in straight lines (happens a lot around here, not enough corners) it will make the bike want to stand up and not want to turn. So, you can kindasorta compensate for worn tires up to a point by lowering front ride height as the tires wear ... of course, eventually it's time for the proper fix, new tires.

And, spring preload i.e. "sag" settings - to be discussed below - plays into this. When you are riding straight up and down and you initiate a turn, what matters is not the topped-out (no weight on the tires) ride height ... what matters is the rider-aboard position of the suspension, which is the total of the ride height setting minus the rider-aboard sag. I told you it was complicated.

Now ... Swingarm pivot height.

This affects what happens when you are in a corner and you start applying throttle. The geometry of the rear suspension of a chain-driven (or belt-driven) motorcycle is such that the forces that lead to driving the bike forward at the rear tire contact patch, also have a vertical component that tries to plant the tire further into the ground and raise the bike itself up, which is called "anti-squat". This is another fine balance. The same sort of acceleration is transferring weight rearward. On the one hand, you have rearward weight transfer which attempts to compress the rear suspension. On the other hand, you have the anti-squat geometry which attempts to stretch out the rear suspension.

If you have the swingarm pivot too low (suspension lowered too much) you will not have enough anti-squat. The rear will try to slide out in that moment when you first apply throttle before the suspension has had time to settle (compress). Now, as you are accelerating, the rear suspension has compressed ... which leads to ... more rake angle and longer trail, and now the bike wants to run wide on corner exit AND slide the rear tire. This is one of the reasons I cringe when I see bikes that have been slammed low to the ground.

On the other hand, if you have the swingarm pivot too high (raised too far up) acceleration out of the corner will unload the front end too much leading to the bike wanting to wash out the front end as you are accelerating.

The normal range of swingarm down-angle is 11 to 12 degrees with the weight completely taken off the wheels. When combined with the normal range of rider-aboard sag (next post) this will normally place the swingarm pivot height "in the ballpark" of where it needs to be. Any rule-of-thumb like this can only be a starting point for further fine-tuning.
 

·
Super Moderator
Joined
·
699 Posts
Now - Suspension preload and spring rates. Bear in mind that how much the springs compress affects the actual rider-aboard ride height of the suspension as you are rolling down the road ... and that affects "Geometry" as per above post.

The suspension needs to be able to move up and down to absorb irregularities in the pavement and it needs to do so not only while rolling straight down the road but also while on the brakes and while leaned over in a corner. In fact from the handling point of view, the straight-up-and-down condition is unimportant but when loaded due to braking or cornering, it becomes really important.

When you hit a bump, something's gotta give. Either the suspension is going to give, or the tire is going to give. If the suspension ever reaches the bottom travel limit and you still hit a bump, you have no more suspension travel available for it to compress, which means the tire has to take the hit. That's why suspension that bottoms out is bad, bad, bad. (and it's something that I've been fighting with my race bike).

Now, for reasons that are related to "damping" below, suspension that almost bottoms out is almost as bad as suspension that actually bottoms out. When you have a hard compression hit due to whacking into a big bump, or landing a wheelie really hard, the suspension has to do everything it can to avoid slamming into the hard stop. So, the compression damping is position-sensitive. The last 10 millimeters or so of bump travel before the hard stop, have a big extra dose of compression damping. You do not want to get into that, either.

So, the spring rates need to be high enough so that under the maximum foreseeable compression loads due to braking or cornering, plus some reasonable extra amount of bump travel, keeps the suspension out of the bump-compression damping zone of the forks. But, not so high as to upset the chassis over pavement irregularities.

The high-zoot racing teams use fancy data logging systems with suspension travel instrumentation front and rear so that they can analyse where the suspension is operating in its travel everywhere on the track.

The rest of us use a small zip-tie tightly tied around a fork leg and an O-ring assembled onto the shock rod to see how much travel we're using "somewhere" on the track ...

The "sag" is the amount that the suspension compresses with the bike stationary. Rider-aboard sag is the one that matters. There are quite a number of videos on youtube that illustrate how to set it. Starting point for a sport bike is for the rider-aboard sag to be around 25% of total suspension travel. If you have 140mm of total travel available (not unusual) then the rider-aboard sag should be somewhere in the 35mm range. You adjust "sag" by adjusting preload on the forks.

And now for the wrench in the works ... Top-out springs. It is entirely possible that, when you adjust the preload on the forks, and then check your results, you will not get the result you expect! You would expect that an adjustment of 5mm of preload results in a 5mm change in sag ... which would be true, were it not for the top-out springs in the forks.

What are top-out springs? They cushion the extension motion of the forks so that, when accelerating, the forks don't go straight to the mechanical travel limit, and instead they counteract the fork-extension motion so that the forks still can react to bumps. If they were topped-out against the mechanical top-out limit they wouldn't be acting like suspension any more.

Traditionally, top-out springs were short enough and with a high enough spring rate that they didn't affect the static ride position. But, if the forks have long, soft top-out springs, they could. The manufacturers started doing this because doing so makes the static rider-aboard ride height of the bike less sensitive to the weight of the rider.

If you try to adjust front sag and you are not getting the results that you are expecting, you may be dealing with forks that have long, soft top-out springs. It's not a big deal, just be aware that your preload adjustments are kindasorta acting like ride-height adjustments.

So, with sag set, and your zip-ties and O-rings up against the seals, go ride, and see where the zip-ties and seals are when you are done. That's how much travel you are actually using. If it's near bottoming out, you need springs of a higher spring rate to stop it happening.
 

·
Super Moderator
Joined
·
699 Posts
Now, for the thing that everyone loves to fiddle with first, but which they should actually be fiddling with LAST, after the tires are right, and the geometry is right, and the spring rates are right.

There are "body" motions, and there are "bump" motions. Bump motions lead to body motions but they're not the only cause of body motions. Braking, cornering, and acceleration all affect how much weight the suspension has to counteract on both front and rear, and the springs compress and extend to balance it until the spring force balances the suspension load. This leads to the bike pitching fore and aft or heaving up and down. "Pitch" and "heave" are normal descriptions of "body" motions (sorry, car terminology, don't know how else to explain it though) - they're not necessarily something bad. If the bike is leaning backward (compressing rear, extending front) or forward (unloading and extending rear, compressing front) that's "pitch" - it affects the angle of the bike as it is rolling down the road and guess what, that's also changing your rake and trail in real time. "Heave" is the motion of the entire bike up and down (car terminology), it could for example be associated with cresting a hill or going through a dip ... or coming out of a corner (unloading) or entering a corner (loading up and compressing the suspension).

Pitch and heave might sound bad but they are entirely normal suspension actions. What's bad is "uncontrolled" pitch and heave ... which could also be called "wallowing" or "bouncing". These are low-speed suspension motions because they operate in the vicinity of the vehicle's ride frequency ... which is a function of its mass and its wheel rates (the spring rates reflected to the wheels to account for mechanical leverage between the wheel vertical motion and the suspension motion). The ride frequency (that needs to be controlled by the low-speed damping circuits) is commonly in the 1.5 - 2.5 Hz range, with soft-riding luxury vehicles in the lower end of that range and sporty vehicles in the higher end. It can readily be calculated. I just plugged in the numbers for my race bike, which is of known weight and spring rates and the like, and I got 2.2 Hz.

Bump motions force suspension movements at much higher speeds - particularly in compression. If the suspension puts too much instantaneous loading into the chassis, it is perceived as a harsh ride, and in the case of motorcycles, if it forces the chassis to move instead of soaking up the bump, it changes the instantaneous geometry and it may no longer be possible for the wheel to "follow" the other side of the bump back down. Wheels not in contact with the ground - wheelies aside - is A Bad Thing.

So that's the theory, here's the implementation. All modern vehicles use hydraulic dampers. The suspension moves a hydraulic piston and various arrangements of flow-control orifices and spring-loaded valves guides the fluid and applies controlled pressure drops as it flows around the insides of the damper. It should be apparent from the above explanation that we want to have a reasonably decent amount of low-speed damping to keep pitch and heave under control (no "wallowing", no "bouncing") but we DON'T want to have so much high-speed damping that the ride becomes harsh, or forces the tires to absorb the loads that the suspension can't (overloading the tire = overheating the tire on the track), or forces too much of the bump impact into the chassis that it destabilizes the chassis, or is such that the tire cannot maintain contact with the ground.

The problem is that hydraulic fluid flowing through a fixed orifice applies more and more force the faster the fluid flows. A simple damper with a fixed orifice tends to have too much high-speed damping (harsh ride). If you open up the orifices to address the harsh ride, then they have insufficient low-speed damping (wallowing, bouncing ... pitch and heave are not under control). So the dampers are built with stacks of spring-washers that act as check valves (to separate compression from rebound) and also pressure-limiting valves. With small suspension movements the fluid goes through an orifice that establishes the low-speed damping (hopefully effective in the 2.0 - 2.5 Hz range associated with low-speed body motions). If the suspension is forced at a speed higher than what corresponds to this, then the pressure across the orifice builds to the point that the shim stack starts opening to "blow off" the higher pressure.

The "clickers" on adjustable suspension are simply needles that are inserted through fixed orifices so that the effective size of the orifice can be adjusted. This is low-speed adjustment only. (Part of the flow in high-speed movement is still going through the low-speed circuit, so a low-speed adjustment has some effect on high-speed operation, but it is rather limited.)

Some suspension (including that on the H2) have so-called high-speed damping adjustment. But, normally, all this is doing is changing the preload setting of a spring in a secondary bypass circuit. The "main" high-speed damping adjustment is established by the characteristics of the spring-washers in the shim stack.

The newfangled electronic damping adjustments on some bikes are simply automating the "clickers" - the low-speed adjustment. They have no effect on the shim stack ... and that's why the first thing a lot of race teams do is to rebuild the internals the way they want them anyhow, regardless of the electronic adjusters; they frequently ditch the electronic system ...
 

·
Super Moderator
Joined
·
699 Posts
"Everything affects everything else"

It sounds like you want high-speed damping that "blows off" excess compression damping pressure for better ride on bump impacts, but you want good rebound damping to control body motions. BUT. If you have not enough compression damping relative to rebound damping, and you go through a series of bumps, you can get a suspension reaction called "packing down". You hit the first bump, the suspension allows the wheel to compress, then the high rebound damping allows the body to drop down on the other side only to hit the second bump that compresses the suspension further, then the high rebound damping allows the body to drop down even further, and so forth, and before you know it "Why is the bike feeling so wierd on those chatter bumps" and you've bottomed the suspension. So, yes, you want decent rebound damping, but you also need compression damping to balance it.

Rear suspension on bikes these days operates through a linkage that generally has a "rising rate" - the mechanical ratio makes it stiffer and stiffer as it compresses. If you raise or lower the suspension, it puts you in a different spot on that linkage.

On a high-powered bike ... you need healthy compression damping in the rear. Squishy rear suspension plus a wicked rear-end slide plus either rider or traction-control intervention to cut power in an attempt to keep the slide under control, results in suspension compressing as the tire re-grips ... and then launching the rider in a high-side. Firm rear suspension will force the tire to continue the slide as it tries to re-grip. Better than launching the rider and crashing.

It is not possible to have suspension that operates ideally in every conceivable circumstance. There is always a trade-off.
 

·
Registered
Joined
·
1,412 Posts
Pretty hard to add anything after those last excellent posts.

I'll just say this...look in the manual.It should have factory settings in there...which is where it sounds like it is right now.Do ONE setting at a time.Start with preload.Set to factory setting.(rear).push on seat firmly.Does it abruptly bounce back up when pushed(probably what it's doing now).It should rise in a second.With no settling at the top stroke.Turn the preload adjuster counterclockwise about three clicks.Now,to the front.Same thing here.It should behave the same way.1 second to rebound.Apply front brake...push down.No dropping after the stroke.Ok.NOW...turn preload counterclockwise three clicks turn on each tube.Check the rebound action.It should be rebounding a bit slower,but not topping out then falling any.Go ride.See how that feels.Front and rear suspension SHOULD rise at the same speed pushing firmly on the seat and releasing.Watch closely.You'll see it if it isn't.IF the top out happens and the suspension(s) 'settle' at all...it's probably going to feel sloppy in some way.Either in turns,or it may bottom,which you'll feel and hear.If it's still too harsh,turn the preloads out another few clicks,equally,and ride again.Start with that.It can be softened up...I softened mine a bit.You don't want the bike to start wallowing in a curve.Make sure it's not doing that leaned over and at a good clip.If it is,snug the preloads up a small amountYou do not want the chassis pogoing when you add front or rear brake.Slightly firm dive,but nothing crazy.Keep working with it,you'll find a sweet spot for you.If you get 'lost' on how many clicks whichever way,go back to the manual and start over.I'm 165 lbs.Mine is smooth as glass,no harshness,yet it handles excellent,never any drama.The neutral(taking hand's off in a curve' is a good way to test the steerability.It should as was mentioned remain virtually steady.Adjusting the forks up or down will definitely change the factory steering action.Personally,I'd leave that area alone.

Take her for a spin.If that corrects it,you're basically done.HOWEVER,compression damping may also need to soften just a bit also.And rebound adjustments.Same thing...small amounts counterclockwise(clicks).Go ride after each adjustment.Includes rear damping adjustment as well.
 

·
Super Moderator
Joined
·
699 Posts
I've been fighting a rear-tire-wear issue for the last couple of seasons on my race bike, which is a Yamaha FZR400.

The issue cropped up after installing a set of Dymag magnesium wheels (17x3.5 front, 17x4.5 rear, can't go any wider on the rear, I have no more than 2mm of clearance between the tire and the chain) and switching to Bridgestone slicks that are the same sizes used by 250 Grand Prix bikes ... lots of grip. Took a while for me to get used to it but once I got somewhere near a decent cornering pace, the bike started destroying the right side of the tire in the carousel at Grand Bend. (Satellite view https://www.google.ca/maps/place/Gr...66f5bcaa!8m2!3d43.2933105!4d-81.7194525?hl=en the corner in question is the one at the bottom of the picture when going clockwise).

The O-ring on the shock rod revealed that the shock was bottoming. The bike felt OK on track but destroys the rear tire at race pace. At other tracks that don't have this long corner, it doesn't happen. (If I'm not up to pace, it doesn't happen, If I'm held up by traffic, it doesn't happen, etc.). Evidently the shock (which is a Fox Twin Clicker ... vintage!) was not designed with the grip of today's tires in mind.

Step 1, stiffer shock spring. Not enough. Step 2, increase rear preload (less rear sag). Nope. Step 3, stiffer shock spring again (about 13.5 kg/mm now, which is off the scale by modern 600cc sportbike standards). Getting there. Increase rear preload again, now at about 25mm rider-aboard sag. Now it's not bottoming any more, but it's still destroying the tire.

The next discovery is that no matter what the rebound clicker adjustment is set to, the shock rebounds too quickly. Step 4, replace the shock oil and recharge the gas reservoir in the shock. Nope. This was pretty much one weekend at a time, and accounting for a couple of cold or wet weekends where I wasn't up to speed, that was more than a whole season to get to that point. Further work required intensive fiddling with shock internals (the shim stack) which would be a winter project ... which is now.

So now the shock is off to the shop for the winter for them to fiddle with it. Fox no longer supports this model of shock so we are on our own, hence the amount of time that this is taking. With the shock out of the bike and the bike hanging by tie-down straps from the ceiling, the next step is to measure the motion ratio (the ratio between wheel movement and shock movement). That has been established to be 2.67:1 in the normal range of suspension motion ... from 0.5" extended from nominal ride height to 1" compressed from nominal ride height (as established by a 2x4 piece of lumber sitting under the still-installed rear wheel) and measuring the distance between the shock mounting points (with the shock not installed). This is quite exceptionally high by modern standards; the usual motion ratio is 2:1 or possibly a smidge more on current 600cc through 1000cc sport bikes. No wonder it wants such high spring rates. But with that, it also needs more preload on the shim stack so that the damping is in a useful range. The current suspicion is that the high spring rate is "blowing through" the high speed damping circuit, forcing the shims open even during normal suspension motion, and that the resulting messed up damping has something to do with the tire wear. We know that turning the damping adjustments between minimum and maximum, rebound or compression, accomplishes nothing perceptible ...

You'd think that on a 28 year old bike, this would have been sorted a long time ago, and perhaps it has, by someone else; then we run into the usual trouble of the people that know, not telling, and the people that don't know, spouting nonsense.
 

·
Registered
Joined
·
70 Posts
I changed the front spings on my 2015 bike within 2 weeks of getting it into the garage.
With the front preload adjusters fully wound in, I was still getting 40mm sag. Indicating that the springs were not strong enough to support my lardy arse!

The guys at Ktech were brilliant in helping with spring rates etc.



A mono H2!



If you need any help, just shout. I am based down near Brighton.
 

·
Registered
Joined
·
836 Posts
Discussion Starter · #12 ·
Wow ! Amazing advice that I'm going to make a point of acting on in the coming months , I have never felt confident enough to fiddle with the H2 ,I have been left way behind on suspension technology since the late 80s .
GoFaster bloody good effort, thank you. enzo200500 also , I may one day take you up on that offer .

When my friends follow me on my standard CBX 1000 they laugh out loud when we pull up and seem amazed I'm OK with all the movement going on beneath me , that's the problem I think I've never had to fiddle with suspension to get along but I'm beginning to recognise it's slowing me down on the H2 , not only that it's uncomfortable as it's so harsh on poor roads .

New 2016 clutch and ergo bars being fitted as I write and I'm going to refer back to this post in Spring to sort my suspension out , probably should buy an SX SE but I still feel privileged to own the H2 so I have the" need to heed" good advice . Thank you once again for all the replies.
 

·
Registered
Joined
·
70 Posts
Haha, no problem matey.

I have just fitted some of the ergo bars as well.

Also have a new 2016 full clutch kit in a box somewhere too!

Typical, sun comes out and they chuck more salt on the roads.....
 

·
Super Moderator
Joined
·
699 Posts
When my friends follow me on my standard CBX 1000 they laugh out loud when we pull up and seem amazed I'm OK with all the movement going on beneath me , that's the problem I think I've never had to fiddle with suspension to get along but I'm beginning to recognise it's slowing me down on the H2 , not only that it's uncomfortable as it's so harsh on poor roads .
In a nutshell, too much damping and not enough spring ... Many cars have this issue as well; mine does.

In a slightly more complicated nutshell - too much high-speed damping (harshness), not enough low-speed damping (if you've backed off the clickers to try to address the harshness), and not enough spring.
 

·
Registered
Joined
·
836 Posts
Discussion Starter · #16 ·
In a nutshell, too much damping and not enough spring ... Many cars have this issue as well; mine does.

In a slightly more complicated nutshell - too much high-speed damping (harshness), not enough low-speed damping (if you've backed off the clickers to try to address the harshness), and not enough spring.
I have read and reread your comprehensive answer and it's starting to sink in , for the first time I'm looking forward to playing with the settings , fingers crossed I don't turn it into a pissed jellyfish.

PS , Pissed in U.K. Is drunk not angry
 

·
Registered
Joined
·
434 Posts
Just had a look at a couple of Dave Moss videos; one on comp/rebound setting and the other on sag setting - very informative and a great visual tool for understanding basic suspension setting!

I'm also just a babe in the woods regarding suspension, even after many years of road riding and occasional track days and trawling through several suspension write-ups etc. This is a very good thread to have on any bike site.

Don.
 
1 - 20 of 35 Posts
Top