Humble time - teach me more about 919 suspension/handling
As I am becoming more familiar with the 919 I am, naturally, pushing more. I am noticing a recurring theme with corners - running wide on exit. It's not at a dangerous point yet, but I can see that without special attentions payed it could easily, and quickly, become an issue.
Specs thus far;
*rider - ~175 pounds full gear
*bike front - stock fork, no preload, raised 10mm, damping as per Honda manual
*bike rear - stock shock, full preload, damping as per Honda manual
*tire pressures - f=35 r=38
*riding style - racer wannabe? Not sure how to describe it other than with a question - Is the world my race track? "No". But really, i'm not too crazy out there, fast, but not Rossi. I corner with the desire to exit it.
I'm not gonna sit here and say what I do and don't know or have or have not experienced because it doesn't matter much. You guys know this bike, you tell me, please, what I can/should look at. What are the bike's characteristics that I should be aware of that can help me to be better educated with this regard.
Thanks.
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Andrew (aka hunnybun)
05 919 and 04 599 shared with the missus (Jenerator)
Have you set the sag on your bike? Made a world of difference for me having it setup properly with the stock equipment. Also I found the 10mm drop in the front to be un-needed. Yes, it provides a quicker turn-in, but it just seems to be more stable all around at stock height.
My $0.02. I'm a newbie, with little (if nothing) to offer here other than my opinion.
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Have you set the sag on your bike? Made a world of difference for me having it setup properly with the stock equipment. Also I found the 10mm drop in the front to be un-needed. Yes, it provides a quicker turn-in, but it just seems to be more stable all around at stock height.
My $0.02. I'm a newbie, with little (if nothing) to offer here other than my opinion.
I found that my riding style has changed a lot when on the 919 vs super sport bikes, I almost always sit upright and counter steer, hanging off just does not work well for me on the 919.
As I am becoming more familiar with the 919 I am, naturally, pushing more. I am noticing a recurring theme with corners - running wide on exit. It's not at a dangerous point yet, ....
Well, actually, it's already dangerous isn't it?
Wide on exit might mean you are carrying too much speed on the way in, or you are picking up the throttle too soon or too hard as you leave the corner, and pushing yourself wider.
You could counteract all this with more lean angle, but maybe you don't yet have confidence in your grip to lay it over any more than you are already. In which case, take some speed out of the equation, and give yourself some safety margin.
You wanted to focus on the bike, but I'm going to tell you something because going wide is a really dangerous event.
The number one cause of going wide for any rider with less than racer speed is focus: your bike will go where you look if you relax and trust the bike. Very rarely is a go wide situation a result of exceeding a bike's capacities. Many accident investigations have made this conclusion.
Target fixation on where a rider thinks they are going to go (shoulder, ditch, guard rail) actually make it far more likely that they will go there (with the addition of survival reactions like coming off the gas, getting on the brakes, etc.).
Best reaction: stay on the gas to maintain proper weighting off of the front tire (keep front tire traction), look deliberately around to the corner exit and relax, continue the counter-steer and let the bike do the work.
The number one cause of going wide for any rider with less the racer speed is focus: your bike will go where you look if you relax and trust the bike. Very rarely is a go wide situation a result of exceeding a bike's capacities.
Best reaction: stay on the gas to maintain proper weighting off of the front tire (keep front tire traction), look deliberately around to the corner exit and relax, continue the counter-steer and let the bike do the work.
What he said.
Although the suspension benefits greatly from upgrades, and good tires are important, Riders using great technique on old tires and the stock suspension could probably whip me on my upgraded suspension/new-tired bike...so, a significant percentage of the performance is the technique of the rider.
Seeing as your rear has damping adjustment, it means it's a 2004 or later model with the mush rear spring.
Are you really running the rear spring at full preload, or is it a full soft ?
How hard do you get on the gas when you leave a turn ?
How much throttle do you using mid turn and on ?
Do you more or less coast in and coast through?
Do you use some maintenance throttle all the way through ?
What are you running for tires ?
Is this on the street only ?
Are you grinding your footpegs at all ?
Wide on exit might mean you are carrying too much speed on the way in, or you are picking up the throttle too soon or too hard as you leave the corner, and pushing yourself wider.
uh no... Wide on exit is generally a function of geometry in that the bike usually doesn't have enough trail.
Proper suspension set-up is a combination of geometry (front & rear ride height) which overlaps into the sag numbers (springing) and then damping characteristics of the suspension. They are however 3 separate facets of tuning the handling of the bike.
At the cost of overstepping my limitations, might I chime in and say the PO might simply be hitting his apex too soon? He doesn't know what sag is, so it's not out of the realm of possibility that he also doesn't know how to choose a line in a corner. Since I know without a doubt that the previous four posters (at least) have way more experience than me, I'll leave it to you guys to explain what that means if the PO doesn't understand it.
uh no... Wide on exit is generally a function of geometry in that the bike usually doesn't have enough trail.
Proper suspension set-up is a combination of geometry (front & rear ride height) which overlaps into the sag numbers (springing) and then damping characteristics of the suspension. They are however 3 separate facets of tuning the handling of the bike.
...and what the rider does plays no part? The bike's going wide all by itself?
...and what the rider does plays no part? The bike's going wide all by itself?
Yea pretty much... If the geometry is off causing the bike to run wide on exit the only choice the rider has is to let off the gas causing the geometry to be altered to keep the bike online.
Or you physically correct the problem by altering the geometry increasing the trail by raising the front end or by reducing the offset of the triple clamp etc, but what do I know...
LDH - I think you are over analysing from the perspective of a racer. You know damn well that you could kick most of our asses on a wreck of an old bike and not go wide in turns!!
For non-racers I stick with my premise that target fixation on the hazard (shoulder, ditch, etc.) and panic reactions of letting off the gas and braking are WAY more relevent in going wide than bike geometry.
Let me preface this by saying I don't think I have ever had a problem with the 919 going wide on corner exit. The 919's lazy geometry numbers are very compliant, let me rephrase that, very forgiving in my opinion. I also find the stock front end on the 919 that most people complain about being too soft to be very friendly in the way it dives and alters the geometry of the bike while trailbraking to aid in the agility of the steering the bike into the turn. If you are smooth on the brakes and not trying to slam them on in a ham-fisted assault every time you approach a turn the bike won't bottom out the forks even under extremely aggressive track conditions.
Back on topic though, my intent on replying to the post above was merely to point out that a motorcycle running wide on exit is not typically a "mistake" of a rider, but rather a function of proper geometry set-up.
Sure the rider might be able to cure the problem by backing off the gas or simply not riding as fast, but the root problem is the bike not the rider. That's like blaming spoons for fat people One really has nothing to do with the other except they are part of the end result. Tell the fat bastards to stop eating so much and you don't have to worry about the spoon.
Fix the bike's geometry and you don't have to tell the rider to slow down...
LDH - You just admitted that you never had a problem going wide on the 919. Others are stating that they are having the problem. Same bike, different rider. It's all about the rider for 90% of us that aren't truly approaching the bike's limits.
LDH - You just admitted that you never had a problem going wide on the 919. Others are stating that they are having the problem. Same bike, different rider. It's all about the rider for 90% of us that aren't truly approaching the bike's limits.
My own 919 never had an issue except when I tried lowering the front end for testing purposes. That is how I know what the root cause of the problem is. I experienced a tiny bit of it when I went to the 60 series front tire riding solo, but with a passenger on the back the rear squatted enough to alter the geometry back to an acceptable level of trail to cure it.
I also rode a guys 919 with an F4i front end once at TGP that ran me VERY wide on every single corner exit. I don't remember the exact details, but I think the F4i forks are shorter which meant the front end was lowered overall.
So, basically, he needs to set the forks back to stock height, set his sag properly (zero preload front and max preload back definitely isn't it), and if he still runs wide after that, go back to square one and learn to ride? Or am I oversimplifying, LDH?
Location: Santa Maria, CA Otherwise known as heaven on earth.
Posts: 1,797
Quote:
Originally Posted by Blackheart
What he said.
Although the suspension benefits greatly from upgrades, and good tires are important, Riders using great technique on old tires and the stock suspension could probably whip me on my upgraded suspension/new-tired bike...so, a significant percentage of the performance is the technique of the rider.
Precisely!
You can play with suspension adjustments, tires and pressures, and dozens of other things and still have the same problem as long as you view the motorcycle as solely responsible for what happens while riding. You are an integral part of the bike, and have the responsibility to listen to it and make adjustments to control inputs and body position to help it to do what you want it to do, and not just for the 919 but any bike you ride from now on.
As an example, the first time I rode my '02 through a corner it tended to try to stand up if I didn't apply some pressure to the inside bar pretty much regardless of how much throttle was applied. This told me I had to move in the saddle toward the inside of the turn (hang off, but not very much) and suddenly it became absolutely neutral. Adjustments to the path in a corner became child's play by a slight change in body position, throttle, and steering. In short order it became second nature.
By all means work with the adjustments available, tires and pressures, and all that other stuff -- it helps to familiarize you with the bike -- but most importantly listen to the messages the bike is sending (such as running wide in corners) and develop refinements to your riding technique. That is the most important adjustment you can make by far.
Infinitely adjustable, made of the finest materials available, and completely sourced from local suppliers -- gotta support the local economy! Order today and know handlebar Nirvana.
LDH - You just admitted that you never had a problem going wide on the 919. Others are stating that they are having the problem. Same bike, different rider. It's all about the rider for 90% of us that aren't truly approaching the bike's limits.
I think this is a valid point, too. Just speaking for my own half-ass skills, I will run wide once in a blue moon, and it's usually because I tipped into the turn too early and hit the apex too soon. I've done exactly one track day and Dallas doesn't have enough twisties to keep me in good practice (my tires are embarrassingly flat in the center), so once in a while I'll blow one. And when you do blow one, it is very tempting to fixate on that rail/ditch/curb/whatever that you're rapidly approaching on the outside of the turn.
Nope, you made it sound just as easy as it actually is...
My guess is the a 10 mm tube rise in a later model 919 would be like a 15 mm rise on an early one.
Rear shock at max preload so there is zero compliance near extension.
Sounds like a great initial setup, eh?
How about stock tube height, adjusters at mid point, rear preload around # 4, and be real smooth in an effort to control the mush rear ?
My guess is the a 10 mm tube rise in a later model 919 would be like a 15 mm rise on an early one.
Rear shock at max preload so there is zero compliance near extension.
Sounds like a great initial setup, eh?
How about stock tube height, adjusters at mid point, rear preload around # 4, and be real smooth in an effort to control the mush rear ?
Unless you're Rob there, then you can just ride around the issues
Unless you're Rob there, then you can just ride around the issues
Nah, can't do that, I'm a Chassis Margin Guy !
I want as much gap between me and the chassis as I can get, hence all my mods and some fairly deep study, certainly well beyond superficial. Hey, who else measured swing arm angle on the 919 ?
Anyway, with the chassis margin now built into the bike, I know two very important things:
1
I am the limiting factor by at least 110% so I know what to focus on and what not to kid myself about and blame.
2
I have fairly conservative margin of safety between my pace and the chassis.
Well, most of the time, but while I may have tickled the edge once or twice, I never went past it. Rule # 1 at home is no getoffs on the family bike.
PS: You are correct about the F4i forks being a tad shorter. I had some internal lengthening done and they are the same as the 919 now, otherwise they'd be about 5 mm shorter. Anyone running pure stock F4i forks and springs would have their front down at least 10 mm from a stock 919.
PS: You are correct about the F4i forks being a tad shorter. I had some internal lengthening done and they are the same as the 919 now, otherwise they'd be about 5 mm shorter. Anyone running pure stock F4i forks and springs would have their front down at least 10 mm from a stock 919.
hmmmm. more info pls mcromo! how do you lengthen the internals and how much does it cost?
hmmmm. more info pls mcromo! how do you lengthen the internals and how much does it cost?
You get that from a full build that includes a modified internal top out setup.
Basically a set of AMA Super Sport level forks with street and track type shim stack builds.
$ 800 or so.
In your case, you can just run your fork cap tops flush with the top deck of the top triple clamp, so obviously you'll have to remove the skinny wire circlips that the F4i forks have at the top.
I have been trying to hone my cornering skills as well. Right now I think Betty White might give me a run for my money but I have found two things that have really helped me more than anything else. First is to relax...I was so tense that I believe my front end could not do what it wanted or needed to do. Second was to look farther down the corner and visualize where I want to go.
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In your case, you can just run your fork cap tops flush with the top deck of the top triple clamp, so obviously you'll have to remove the skinny wire circlips that the F4i forks have at the top.
got it, that's what i'll do. hopefully 5mm isn't too much of a difference lol.
So that's been a lively little thread that has covered a good bit of territory - let's hope it's been of some use to the original poster....
... like you wouldn't believe. Before I make any comments I have one more question. Something that I may have been misunderstanding all this time ...
With regards to me dropping the front end 10 mm - how would this cause the bike to run wide? My understanding is that with this change resulting in a quicker turn-in that it should, equally, result in the ability to "keep the bike down" and NOT run wide. What, if anything, am I missing here?
LDH - spoons, fat people ... love it!
I'll post more tomorrow night, guys. My head is in a very bad place right now. Thanks for the input!
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Andrew (aka hunnybun)
05 919 and 04 599 shared with the missus (Jenerator)
Well, let's hope the chassis guys chime in here again - LDH's earlier post suggests that it relates to loss of trail at the front end as you steepen the fork relative to the rest of the bike by sliding it up through the clamps - but remember you are now asking about 2 different things. On the one hand, you are talking about enhancing turn-in, corner entry, and then going on to talk about running wide on exit...with the approach you are currently taking, you might be in a classic trade-off position....
As I said, let's see what the chassis guys have to say...
but remember you are now asking about 2 different things. On the one hand, you are talking about enhancing turn-in, corner entry, and then going on to talk about running wide on exit...with the approach you are currently taking, you might be in a classic trade-off position....
You rather nailed it.
Raising the tubes does not cause a bike to run wide on exit nor is it a contributing factor in any way in that regard.
Other things do, rider input(s) included.
How hard does he get on the gas when he leaves a turn ?
How much throttle does he use mid turn and on ?
Does he more or less coast in and coast through?
Does he use some maintenance throttle all the way through ?
What is he running for tires and what shape are they in ?
Is this on the track only only ?
Are he grinding his footpegs at all ?
What gears is this occurring in ? 2 & 3 ?
It's a later model bike so it has the mush rear spring. He has gone to max preload so there is zero compliance in the range of full extension, meanwhile it is a mush spring in the normal operating range of stroke.
If he put a zip tie on his shock shaft, my guess is that he'll find it jammed to the bottom and maybe even stuffed into the bore of the snubber. In other words full shock compression from squat.
919s squat like crazy to begin with, and the late model mush spring makes it even worse. The spring is around 865 # /inch, while a minimum of #1100 is needed, and even that is light for track use.
Even after all I have done to my bike, there was still one place on the track, a fast side to side transition in 2nd, that to keep the front end from skating out on exit under gas, I had to be off the seat on the pegs and up over the tank to keep the skating to a minimum.
I too would run wide on exit on my S3 when I first got it. I then learned that delaying the apex would allow me to consistently run much closer to the right side of the road. This technique does not serve well on the track though as it tends to make all corners much closer to a 90 degree corner.
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I too would run wide on exit on my S3 when I first got it. I then learned that delaying the apex would allow me to consistently run much closer to the right side of the road. This technique does not serve well on the track though as it tends to make all corners much closer to a 90 degree corner.
Most newbies turn in too early on the track.
Too early a turn in puts you on the outside edge later on.
Making things even worse is being too close towards the inside PLUS turning in too early.
Talk about creating an impossible situation if one goes in too fast for the resultant effective line.
This is going way above and beyond the scope of the 919, but if you want to learn about geometry I am going to give you your moneys worth right now.
Raising the front end of the bike increases trail AND raises the CoG. This is very common practice on many newer sportbikes to improve the handling and stop them from trying to run wide on exit. They even sell fork cap extenders for the Ohlins cartridge kits to do just that. When you raise the front though the agility of the bike can suffer so many also raise the rear as well to get that quick steering back.
That's also why Offset Triple Tree mods are becoming so common on proper racebikes now as they allow massive changes of trail while other changes are minimal. Even without different clamps the offset changes to the front ride height have very little effect on other parts of the bike.
These numbers vary from bike to bike ever so slightly, but to give you a good idea of how things are affected take this into account:
6mm of taller rear ride height alters the swingarm down angle slope by .4°
That same 6mm of rear ride height alters the trail numbers by 1.5mm
(a very typical mod we do for the Ducati 848/1098/1198 are the 30mm Offset Triple clamps down from 36mm stock so that is a full 6mm of change in trail numbers and again this is done to keep the bike from running wide out of the turns period)
2mm of front ride height change adds .5mm of trail (that means to get the same results of off-setting the triple by 6mm you would have to add like 24mm of front ride height which is virtually impossible on any current bike due to the length of the forks)
That same 2mm of front ride height change is .07° of slope on the swingarm (negligible at best)
When we raise the front end up on our bikes we are basically just doing the best we can with what we have to work with. The proper race bikes all use a different offset triple clamps compared to OEM
As eluded to though there is some personal preference involved in the geometry set-up process and a myriad of other variables as well that convolute the end result. Hell even orientation in minute degrees of the physical engine position in the frame & how many rpms are spinning the crank around internally cause increased amounts of gyroscopic precession to work against you etc. Sometimes just shortshifting a gear or two can significantly reduce the effort required to initiate a turn at speed.
Ultimately you want a geometry that doesn't have the bike fighting you into and out of the turns. If you are having to put pressure on the handlebars in the middle of a constant radius turn to keep the bike from either trying to fall into the turn or stand up through it then you have a geometry problem.
The second part of that issue is finding the compromise to get the bike to steer properly without running wide when you get on the gas during corner exit.
Some riders want that perfect line trailbraking into the turn and make due on the way out while most others will sacrifice some precision on the way into the turn to get the perfect drive out.
But really, i'm not too crazy out there, fast, but not Rossi. I corner with the desire to exit it.
One really has nothing to do with the other except they are part of the end result. Tell the fat bastards to stop eating so much and you don't have to worry about the spoon.
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