Lord Duckhunter

Keep in mind that the reason most production bikes are oversprung on the rear & undersprung on the front is because they are built to haul two people. When you have that much weight on the back of the bike the front end tends to get light under normal cruise conditions and therefore does not need to be as stiffly sprung. Of course the downside is they compress even more when on the brakes, but in many cases this is needed as well to alter the geometry of the bike so that it will steer into the turn on the brakes.

of course riding solo presents different demands on the suspension to achieve proper ride characteristics & again geometry for steering. The faster you go the more important all this becomes. That is why when I sell someone a shock or forks etc I spring each unit to the riders weight not the maximum load of the rider & passenger combined. When riding with a passenger they simply dial up the preload as much as possible & make due and it is still better than a stock ride.

There are rare occasions where I have sprung a bike for total weight of rider, passenger and luggage because the rider uses the bike in that configuration 100% of the time. If you try to ride a bike solo with that set-up it would be all, but unrideable by any AFTERMARKET SUSPENSION standards I could impose or you can think of, but that is exactly what everybody does when they ride a bone stock bike it is just to a slightly less degree...

Sniper

The front and rear need to be matched, working together, is one of the things "the suspention guy" at the track stressed. Out of the box, the front and rear of the 919 are a mismatch for a solo rider, and a big reason why they don't ride and handle as well as they could. (I think)

mcromo44

Echo echo echo re the mismatch, extreme on the earliers, mere bad on the laters.

And a bump up in rate at the front, also effectively increase the compression damping force while weakening the effective rebound force BUT there is an external rebound adjuster on the 04s and later, so some built in remedy exists.
I find the 919 to be really "divey" on the brakes, even at low braking levels.
(I wonder if it was sprung for rear brakers that barely use the front, scary thought that those sorts still exist.)
My guess is that in the range of 0.85 kg/mm to 0.90 is the zone, noting Mr. Mikes selection of 85s.

honda ng gingsa

Balancing the front and the rear, now there's a simple concept I can understand.

I have an '03 that has no suspension adjustments whatsoever. I did a trackday with it last weekend and had a blast and will definitely be doing more. I cannot however, afford to do a major suspension upgrade.

In line with changing springs and oil weight to better balance the bike, anyone willing to make a recommendation for me, 180-185 lbs. in my gear?

mcromo44

What tires are you using and what is your spending limit ?

I'll bet you can buy a used 04 or later shock for less than you can put on a new rear spring alone. Pure guess, 75 $ for the used shock. It'll be around 920 #/inch which is theoretically light for you and track days but I'll bet you find it better than the insane spring presently on your 03 shock. A set of 0.90 kg/mm fronts. Put in decent oil, same viscosity as Honda calls for, as in 10W. (Motul ForkOil Expert is decent and not very expensive, something like that) For sure under $ 250 for all the above. If you want, start with the fronts and oil change which will be under $ 150 total. Some might suggest 0.95s for your fronts, but I'd be careful with that - without some internal reworking such a spring rate will have altered your effective compression damping up and rebound down.

honda ng gingsa

I broke-in a new set of Pirelli Corsa 3's on the track last weekend. Happy with those. Coupla' hundred would be what i'm willing to spend on the bike (dependent of course on what I have in hand after spending on few more trackdays first of course).

So in simple terms, without having the options of rebound and compression damping, we are talking about stiffening up the front with stiffer springs than what's in there now and doing what we can to soften the rear with a softer spring in an effort to better balance the bike for solo riding. Yes?

zaq123

I wasn't talking track there, I was talking street.
.85 spring does not have saficient rate to provide proper sag numbers for 220lbs rider for the street,I am not even talking track.
The way I look at it: bikes should be sold like prescription eye glasses, you pick a frame (bike) and you need to tune-in lenses that you need (suspension)

mcromo44

I think you are missing the point. As in staying within the confines of the stock rear and reasonably balancing to it at the front.
85s will do that.
We are not talking about "ideal spring rates", which would necessitate fore and aft changes which the chap expressly does not want to do and won't do.
You would, I would, but he won't and doesn't need to.

mcromo44

You have it pegged, but mark my words, you will get a range of counter opinions and I'll bet you see some within 24 hours.

Nice tires ! I'm running 2CTs but am getting a set of Pures for the dedicated track day 750.

honda ng gingsa

Yep. Just trying to understand the broad strokes at this point. Will decide on the specific course of action on the springs etc. after a few more track days.

Better tires were a big jump in improving the ride for me. Bit more confidence in trying to push my limits harder.

Thanks for the input.

velodesign

AGAIN. my head hurts.

I love the passion here... maybe i just need to call traxxion and let them smoke my ears off. When i rode mykz650, i just put more oil in and bought some dual prosressives and rode it for a bike. Track days? Not going to happen more than likely, surving the normal roads is enough a thrill for me with texting and teens...but i digress.

In my budget: $300 for new springs front and rear - at least to match 220lbs. I do two up ever other month or so for less than a tank each time.

No track.

Maybe i need to starve myself for 2 months and lose 30 lbs and get to 190. Would be cheaper. Would 190 be acceptable on this supension?? Im only half kidding....

zaq123

I'm sorry but this is wrong concept.
You don't need to balance front and rear, you need to adjust front and rear to achieve proper sag number with you on the bike. If you are unable to adjust it due to your front and rear running out of adjustment, you need to start changing components.
On the 919 if you balance front/rear (leave stock shock and change fork springs to match shock) you will have it set up for ~200lbs rider. So for anyone 190lbs and below or 215lbs and above, this balance will do no good.

rear shock of 919 is f'd up: spring rate ~1000 lbs: 190-200lbs rider, rebound stack is too soft to control 1000lbs spring hence pogo stick effect.
if you are not ~200lbs and use stock rear, you wont be able to get proper free sag and rider sag numbers at the same time.
honda ng gingsa, you being 180lbs most likely this is what you got with stock rear spring, when you get proper rider side, you have way too much free sag



front spring is 0.6kg something, basically for 120lbs person.

mcromo44

Now I'm feeling bad.
I don't to make anyone's head hurt ................

mcromo44

Just saw this now.
Traxxion or RaceTech, it matters not. RaceTechs in my 919 and Traxxions in my 750. Use a hand held pipe cutter for cutting the spacer lengths.

zaq123

you need .95 kg for the front to balance 919 stock rear - street
1kg front spring to balance stock rear - track
To make it all work - you need to be 200lbs guy. So velodesign yes, lose 20lbs and you save money on the rear spring.

zaq123

both of them are Eibach springs. Eibach makes spring for Racetech, Eibach makes springs for Traxxion

mcromo44

Need ?

As for rates, I'm 165 in the skinny, run 925s in the front and 1100 # per inch on the back and the chassis is nicely balanced for and aft and works well at the track.

honda ng gingsa

Aaww man. Just when I thought there was something we could all agree on.

...I'm gonna have to read a book or two to get the hang of this aren't I?

Haha. Well I'm open to learning what I can here.

zaq123

and your sag numbers are..... they will indicate if your suspension setup properly, not "my bike runs dynamite on the track". To check if your bike setup properly, any suspension tuner will do something like this (video), he won't ask you what do you think ,he will tell you to get your ass on the bike and shut up.
I don't know what else I need to say in order to explain it to you

here enjoy

mcromo44

I missed something, seeing as the keeners are hard at work tonight.
Let's suppose a 1.0 was used.
That means the resistive (compression) and restorative (rebound) spring energy available is up by about 25 % over stock.
Which means the stock compression and rebound valving, already bad, is then whacko out to lunch.
Remember, any change in spring rates has an effect upon the effective damping force in the compression and rebound circuits. Big spring rate changes need revalving for that and that alone. If no valving changes are to be done, be real careful how far you go in spring rate changes.
Remember, ANY website or tabulated spring rate info is predicated upon the valving being made to match said spring rate. The real plan is a synergestic approach to spring energy and damping forces.

sike

Wow, after watching that video I have learned something. I should ride my motorcycle with my feet on the ground so that my suspension doesn't have to hold up all my weight......

velodesign

ok. losing 20 more pounds, and i should be goo dwith stock rear right?

front needs .95, good oil and a new spacer...right?

You guys in internet land are awesome - and i sound like im 14 because i use my netbook to type in bed.

my list of things to do:

1. start losing weight again (lost 15 already)
2. static sag test
3. save some cash for new internals for springs, oil, valves for front.
4. not worry about the rear until next year...

sound about right everyone? ANYONE up for making that spreadsheet mentioned earlier??

mcromo44

I thought it was about spring rates, so now we've added sag.
Excellent.
Simple sag is one element, and just one. Aside from dampening, it's spring rates, free and rider sag, and front and rear ride heights.
I know exactly what my sags are, and I know exactly how much I lengthened my rear shock to get the rider on ride height where it needed to be after implementing Traxxion style 10-11 free sag soft top out. And if anyone is interested in how to better setup rider sag on high stiction front ends like 919s then read on:

McRomo44 (SS) @ Dec 2009
My biggest beef with the 919 front end (mine is fully Race Tech valved/sprung/oiled) is the Stiction. I get as much as 15 mm of Stiction when doing classic Rider Sag checks. (With big Stiction numbers like 15 I don't not believe in using the +/-averaging method)I think the fork seals are too good and grab to some degree. The tubes are absolutely dry to the touch, unlike the tubes on our 600 and 750 that leave a barely detectable film you can more see than feel. I ended up creating a dynamic type Rider Sag check in order to get Rider Sag numbers I could trust. ( Hence my made up term “Dynamic Rider Sag”) Here is the method : 1 do a ballpark 35 mm Rider Sag or whatever number you are after. 2 get the front end off the ground, tire not touching and front end unloaded and full extended. 3 Add 5 mm to your target Rider Sag value. 4 take a piece of electrical tape and wrap it around the fork tube with the bottom of the tape at your Rider Sag + 5 mm value. 5 gently lower bike and get ready for a short slow ride close to home that has at least a 100 yard straight run. 6 putz along at 10-15 mph. 7 give it a touch of gas to unload the front end a bit and then declutch and stay off the front brake and just coast. 8 the coasting along will give enough input that the front end will find its true Rider Sag equilibrium point. 9 gently use the rear brake and come to a slow stop. See where the tape is in relation to the top of the fork seal, and now you know what your Rider Sag really is. Then go about changing your spring spacer length in pre 04 models or use your external ride height adjusters on your 04 and later models. Personally, I am using 95 mm spacers with my Race Tech 0.925 springs, 125 mm of oil height, and have the top 2 rings of ride height adjustment showing. The fork tubes are in the standard position in the clamps. Doing lots of Track Days miles on 2CTs. The rear is Penske with 1100 #/inch spring, running 11 mm of Free Sag, with shock lengthened 6 mm more than stock. I weigh 165 # before riding gear.

I think that much of the Stiction is due to the extremely effective fork seals.
You are also right about getting it where you like it, and if one doesn't know exactly where that is, as long as it’s good for you and your road riding it is OK. It really only becomes important if you are doing track time and playing with front and rear ride heights.
When you start playing with settings to that degree, you really want numbers front and back that you can be confident of. You need that for diagnostics as well as set up changes. And if you set up a 919 front end by the Classic Method, you do not know where it really is in terms of numbers you can talk to yourself or a chassis guy about.

------------------------------------------------------------------------------------------------------

Wrist Twister’s Rob Tharalson @ Jan 2010
Air-powered Industrial Ball Vibrators to take out Stiction for Sag Setup.
I went to a local industrial supply and bought a small one, hose clamped it to one fork leg with a thin piece of rubber to protect the finish, and fired that puppy up. Immediately the forks dropped to a new position and could be moved either way with the force of one finger on the triple clamp. Suddenly the sag adjustment took all of three minutes (depending on where the adjuster / shim was), and the difference between drop to set position and rise to set position went from 5mm to less than 1mm. Of course it was still possible to set it wrong, but at least it was consistently wrong!

mcromo44

To anyone watching this video, BEWARE.
I have the highest regard for Mr. Moss, have all his web articles and DVDs. He is NOT presenting a definitive method for sag setting in this video at all, and merely a quickie insight as to how ride heights due to sag changes vary as a function of varying rider weight for any given fore and aft spring set up.

See how as much as 15 # of riding gear is missing.
See how the feet are resting the ground, likely as much as a 10 # weight transfer.
See how body C of G is not in the true riding position.
See how no stiction checks have been done.
Etc.
Again, Moss is good, but don't see this video for anything more than what it is, and recognize it for what it is not.

McRomo44

mcromo44

Well, I'd say there's been a certain level of interest as a result of this thread's initiation a scant 5 days ago.

mcromo44

if you are, check out the Mechanical and Technical section of the website and look for "Why Invert The Front Forks?" There's some interesting info and back and forth there too.

mcromo44

Without a helmet and while wearing sandals, but I digress ......................

mcromo44

Actually, the yo-yo ing or pogoing is more likely inadequate low speed compression damping. That is if you are referring to such a reaction from throttle immediately after transitions. That was certainly the case with mine as since remedied.

Farab

Is there a basic guide -book, good youtube video, website - for beginners explaining suspension setup and terminology, etc., that anyone can recommend? I am keen to learn.

Sniper

True wisdon is knowing where to find andwers.

I like good suspentions. But I'm still pretty clueless about them. But that's OK. We have Mike at Dan Kyle's to sell us the right stuff, and the guy at trackdays at Putnam to set it up.

It's all good.

Farab

Yes, I'll do some digging myself. Just thought someone could point me in the right direction to make a start. I enjoy knowing how stuff works.

mcromo44

Absolutely !

1
Go to the RaceTech website and get the free downloads you are interested in.

2
Go to the David Moss / Catalyst Reaction Suspension Feel The Track website and get the free downloads you are interested in. (Check out the related OnTheThrottleTV site too, for purchases plus more stuff)

3
Go to the Traxxion Dynamics website and get the free downloads you are interested in AND buy the Suspension For Mortal DVDs and the accompanying booklet that is still available at a bit more cost.
(Max is what I call a "soft top out rear" guy, as in calling for 10/11 mm free rider sag, which typically needs shock lengthening to get the ride height where you need it to be when rider sag is evaluated (and simple spring rates alone are NOT the correct solution here !). His method works, but the issue of shock length compensation is not expressly made, and REAL easy for a newbie on their own to miss.)
4
Buy a copy of "Sport Bike Suspenion Tuning" by Andrew Trevitt.

5
Once you have done 1 - 4 and want more, then consider David Moss's DVDs, especially if you are looking for "tire reading" knowledge.

mcromo44

6
This should be # 1
Check out the Sport Rider Website for free downloads. Look for Suspension Tuning Guide. They have done some excellent articles in the past on sag setting. Look for Feb 04 "Five steps to a great suspenion setup.I'm not sure if it is available as free downloads or back issue purchase type articles.


You are now armed to the teeth with well written understandable info, science, principles and concepts.

Lord Duckhunter

Be careful with all the videos and crap out there... A lot of it is aimed solely at getting money out of your pocket. Way too much of it is centered around taking advantage of what people don't know... Many suspension tuners prey on ignorance and take credit for making a new rider faster when it has more to do with the rider simply gaining experience in the seat than any "tuning" that was done to the suspension. Any new rider to the track is going to drop 5-10 seconds off their initial lap times by the end of a weekend, but just because they took their bike to a suspension tuner the tuner makes the claim that the rider went faster because of their expertise with the suspension etc...

I recently watched a suspension guys video where he is trying to set-up an Ohlins shock by pushing up & down on it in the paddock then adjusting the damping settings (which btw just does not work as you simply cannot push up & down on a high performance shock & be able to emulate what really happens at speed on the track). The rider then goes out and immediately tears the shit out of the tire and then comes back into the paddock & the video concludes with the suspension tuner changing the settings to FIX the tire tearing problem that was most likely started by incorrectly setting the damping to begin with...

Here is the real bottom line with all of this:

1. Your stock OEM suspension sucks ass period. Say what you want about revalves, resprings whatever, but all OEM suspension pieces are built to a price point and actual functionality is a distant second thought. The damping and spring rates are set up for a generic across the board rider weight designed as a one size fits all model.

2. High Performance aftermarket Ohlins suspension (and various others to a lesser extent) right out of the box will be custom tuned to the requirements of the bike taking into account the rising rate of the swingarm all the way to the true needs of performance riding and comfort. It will give you a better range of adjustment that is already in the proper range (that the stock shock isn't). We custom spring every shock & set of forks we sell to the riders weight & riding style before we ship it out the door so all you have to really know how to do is set the sag properly (which I can teach anyone in 3 minutes on the phone) and then go ride!

YOU DO NOT HAVE TO BE A SUSPENSION GURU TO USE A QUALITY AFTERMARKET SHOCK BECAUSE THE RESEARCH & DEVELOPMENT HAS BEEN DONE FOR YOU.

Trying to make the stock shit work properly is where you need a bachelors degree in engineering and a masters in VooDoo.

3. Seat time: Now it is up to you to build up your own skillset by trial and error which is much better than trying to decipher someone else's writing or theory which in many cases is not easily conveyed or just plain wrong. I mean once you have the quality suspension installed you now have all the tools you need to have that larger margin of error & a larger margin of safety. You are also now in a position that as your speed increases and you do start to suffer some sort of strange tire wear or handling issue that you can actually make a small damping adjustment (one or two clicks) & immediately notice a difference in both the actual feel of the ride as well as the amount of tire wear etc. This is a stark contrast to a stock shock that is in the incorrect damping range where you can turn the dial all the way from open to close & sometimes still never feel an appreciable difference or at least not any setting that is beneficial (i.e fixes your problem) in the entire range.

Farab

Thanks MCROMO44, will check it out.

LDH thanks also. I am not aspiring to become a suspension guru like yourself, but at this stage at least, I am interested in understanding the basics and termonology. As I said, I just like to know how things work, I like learning about stuff I have an interest in.

I appreciate your thorough reply.

Lord Duckhunter

Just for clarification I'm no guru... I know a pretty good bit about certain bikes (mostly the ones I own or have owned) and I am pretty well versed in proper set-up of Ohlins products, but I've only been learning & working on suspension for 10 years & every time I think I know what I am doing something happens that throws me a curveball and changes the rules.

You have to be astute, willing to accept other ideas and adaptive because there is a lot of evolution in the suspension that is not always so obvious from the outside. Yes new technology is trickling down inside the suspension pieces, but changes to the geometry of the bikes from rake/trail numbers, longer swingarms, adjustable pivot points etc are making it so much harder to figure out what to do to make the bike handle properly. There is so much more to it than just sag numbers & tire wear. For many current sportbikes gone are the days of simply raising the rear and/or lowering the front of the bike. More trail in the form of raising the front and even through the use of offset triple trees is becoming more & more common than ever before as are aftermarket linkages.

mcromo44

I can not disgree with a single thing LDH said and he has pegged a number of points real well. That's not to say that I fancy myself to be in his league - which I'm obviously not, but my studies and experience to date say his words ring true.

sml2727

When im rideing my bike I have no clue what im trying to feel for so thats why I havent changed anything, heck I never turned the little screws on the thing.

I just ride it and change the oil thats pretty much it.

Lord Duckhunter

To a large degree I envy you... Sometimes it's hard to fathom just how I went from being nothing, but a common street rider on a cruiser bike

TO

a guy that doesn't even own a car and rides his motorcycles everywhere rain, snow or shine

TO

riding my bike to trackdays and riding back home

TO

being an instructor that basically only rides at the track with a dedicated trailer that hauls 3 bikes, enough tools to drop the engine out of the frame on the spot, shock spring compressors, spare parts and bodywork for the bikes, tire warmers, spare wheels and rubber mounted up & always ready to go.

Things were much simpler and honestly more enjoyable when I just rode the bikes for fun... Something inside of me makes me want to be better though. I constantly want to improve my own ability as well as the bikes I ride. I guess that is probably why I have always considered the 919 the best streetbike I have ever owned. It is the only bike that I was content to basically leave it alone although it didn't start out that way. I went through a a lot of mods with it before I realized that most of them were futile and that the cosmetic mods alone were not what made me happy anymore and since I couldn't really up the performance I just stopped mesing with it. Took the belly pan off mostly because it made oil changes so much easier and smiled every time I threw a leg over the saddle. Sometimes I would just sit on it in the hallway (if I could get the cat off of it that is...)

honda ng gingsa

LDH, hypothetically if one was willing to pony up for an Ohlins unit for the rear, what would one have to do to the stock front end to "balance" with the Ohlins out back?

Just match aftermarket springs to rider weight and ride?