Suspension Advise Pleasegreenspun.com : LUSENET : MV Agusta F4 : One Thread
Front suspension is very soft, even for fast road, now i have increased the rebound and compression, but the front still dives under braking (not even heavy breaking as brakes are not exactly great!) Now i love the bike, it goes exact where i look, but would just like to reduce the front dive when on the anchors. Do i need to increase the front preload? will this really make a difference. My rebound and compresssion are 4 from max stiffness, which is miles of the standard setting fromm the book. Should i put these closer to standard (for fast road) and increase just the preload? I also find that any ridges in the road don't half get felt through the handle bars, and any small potholes almost knock the front in the air like i've hit a brick or something!! and i fear it is because i have tried to overcome the diving by dialing in too much rebound and compression, even though they still dive excessively. As you can probably tell i know nothing about suspension set-up but does anyone know where i'm coming from?!!!
I am 15 stone 6ft4, and am very keen to know what everyone else has done to their suspension settings, how they ride etc. Just a quick reply, and feedack would be great.
please give me any feedback you can,
many thanks, as always, Paul
-- paul h (email@example.com), May 24, 2004
Suspension Setup Course (DVD)
-- mod (firstname.lastname@example.org), May 26, 2004.
yep, you've twiddled and knacked it (just kidding) now i'm no expert but i would say your front end is feeling every bump and kickin' out 'coz its too hard. the road ain't a race track, it needs to move or your gonna be in serious pain after a short ride if it doesn't. all thats happening to your suspension is its pumping down (or up) depending on which way you look at it ie over multiple bumps it can't react quick enough coz its so stiff. my advice to you would be set the front and rear compression/rebound to the books stiff road settings and, here's the important bit, get the preload (both front and rear) set up correctly (you'll need a mate to help). this controls the ammount of movement and at what level the bike sits at with and without you on it. the rebound and compression control the rate or speed at which the springs move across a given distance so in other words if your springs are soft setting the compression to hard will not stop it diving, just the rate at which it dives. if the preload set up does not cure it then its new springs to suit your weight which by the sound of things in your case would invariably be stiffer. hovever i weigh about 14.5 stone butt naked which puts me at 15ish kitted out and i do not notice excessive dive on my bike.as for the brakes try new fluid (v. high temp stuff) and pads if that fails carbone lorraine are supposed to be good i'm waiting on some myself. i'll mail you what i have on suspension set up it's well worth the read and i'm sure you'll be enlightened.
-- iain (email@example.com), May 24, 2004.
Firstly Paul i mostly agree with what iain has said go back to the std firm settings.front end dive is good as long as it's not excessive and is controlled,To find out whether it's excessive is the first job,attatch a cable zip tie around one of the fork legs as close as possible to the staunchon with the bike on the side stand.Next go for a ride and brake as hard as you will ever do in all riding conditions.Look at the cable tie and if it is less than about 3/4 of an inch from the bottom of the fork leg you must increase preload till you achieve this figure.if you run out of preload then you need heaver springs.Next is damping,what you are trying to achieve is the forks dive at a fast but controllable rate to the 3/4 measurement(compression damping) and stay there without rebounding or pogoing as you flick the throttle during downshifts,this is done with rebound damping adjustment.so you need to experiment and do one change at a time and log them.what you are trying to achieve is this,max ammount of dive into the corner at a controllable rate while still leaving a small amount of travel to absorb any bumps this will speed up the steering geometery and make the bike turn in easily,as the suspension load decreases from the braking forces it should be seemlessly replaced by the forces generated by cornering(this will keep the steering predictable and let you adjust lines mid corner with the same quick steering that got you in) till approx the time you get back on the throttle.as stated before the rebound should keep the forks stable on the way in when flicking the throttle an allow them to extend when you get back on the gas on the way out to keep the front wheel on the deck and provide steering.the reason dive is good is because it speeds up the steering on the way into a corner,transfers weight onto the front tyre where 98% of braking is done on a sports bike,it lowers the c of g which helps turn in and it minimises the the chances of the back wheel coming off the deck.(this last one takes some thinking about but none the less is true and is why no GP bikes use anti dive mechanisms)As a matter of interest the limiting factor in braking of all real modern sports bikes on a dry road is the back wheel comong off the ground and the control dramas associated followed by the rider going over the bars.front wheel lockup is no longer a factor on dry roads and upright braking.trail braking? well thats another story.
-- philip costin (firstname.lastname@example.org), May 24, 2004.
Well Paul, you've opened up that great can of worms that is suspension setup, expect some long replies, but of course what works for one persons riding style may be totally wrong for the next person, and then you have all the different tyre combinations to take into account. Don't you just love biking !
I've also noticed a fair bit of dive on the brakes,and have increased both rebound and comp a couple of clicks to help, but if you go too far then as you say the front becomes quite harsh. My hunch is that the springs are not designed to cope with the larger gentleman and I will probably get mine off to Kais for a revalve and respring at some point. I had my RSV forks revalved by them and it made an unbelievable difference, don't have the number to hand but they are based up near Manchester and have regular adds in the bike press. Give them a call and see if they can help.
Here's a quick thought for you, If Valentino Rossi offered to setup your suspension most of us would jump at the chance, not me, I'd have Vale ride the bike, then get Gerry Burgess to set up the suspension !!
Suspension, Best left to experts !
-- Craig (email@example.com), May 25, 2004.
With all due respect to Craig,i cant agree with his last comment,of "leave it to the experts",my fellow countryman Jerremy Burgess wasn't born a suspension expert he had to learn the art and so can you Paul,it's just a matter of applying yourself and be willing to experiment.By all means consult professionals for their advise but you must have at least some basic knowledge gained through experimentation and reserch to enable you to sort the wheat from the chaff so to speak.You ride as i do a modern sports bike(mv) with what i consider to be reasonable suspension,not brilliant but probably better than the average rider can fully utilise once set up (it's a bit like horsepower,i haven't met to many A grade road racers that can fully utilise on the race track the power a std gsxr1000 can make, despite what they say)it's just up to you to put in the time to become the expert and extract the potential.If your unwilling then thats fine but from my perspective sports bikes are all about corners not dyno charts and top speed figures.The potential exists in your bike to be i suspect better than you are, (and me for sure)it's up to you to extract that potential and learn along the way,to become that expert.
-- philip costin (firstname.lastname@example.org), May 26, 2004.
This site is full of long winded, straight armed, can't ride their way out of a wet paper bag WFCMF's (as in throttle wide fuckin' closed you know the rest)!
The quick cheap fix is 1.0 KG/mm springs (preferably Ohlins) for a rider your weight. Most would use .95 KG/mm. Anyone increasing oil weight to stiffin their suspension never rode hard enough to heat the oil up or is just plain stupid!
The proper solution is to throw your forks & shock in the back of your garage & buy something worthy of that marvelous chasis. I am currently useing Ohlins FG 750 forks & a Penske shock (note the hillbillies at Penske know dick about bikes & you need to let them know there is no place for the reservoir but along the frames main rails i.e. the baided line for the reservoir needs to be 1 1/2' -2' long) let me know how serious you are & I'll give you an exact leangth.
-- sean crane (email@example.com), May 28, 2004.