Getting better rear tire grip

Started by bsavoie, August 05, 2004, 07:26:57 AM

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bsavoie

I have an SV, and race in the lightwieghts.  I find the bike is handling great, except when I drive out of corners.  I usually carry a lot of corner entry speed, and maintain it through the corner.  This will usually let me gain on the people in front of me.  The problem comes when exiting the corner, my rear end doesn't always want to hook up that well when on the gas, I see this every lap.  The guy in front of me always seems todrive out faster, while I am sliding.  I am not a suspension expert, but am thinking maybe not enough preload?  Any thoughts?  I use a fox twin clicker on the back of the SV.  Any help is appreciated. Thanks.

Protein Filled

I used to have a Fox twin clicker on my bike and swapped it for a Penske. Huge improvement! I am not saying that the reason why your bike is sliding, but the Penske is tons better.

You can get the Fox revalved with better internals if you wish. That may help quite a bit.

One more issue could be your riding style. The people in front of you that are getting a better drive may be setting up the corner just for that, so while you are going in there at a high rate of speed, you are sacrificing corner exit. You may want to try and enter the corner a bit slower and see if you gain more with the drive out. Corner exit is one of the most important things for getting around a racetrack faster.
Edgar Dorn #81 - Numbskullz Racing, Mason Racin Tires, Michelin, Lithium Motorsports



Don't give up on your dreams! If an illiterate like K3 can write a book, imagine what you can do!

zoner

Could be a number of things.  What's the rider sag and how much ride height in the rear?  Have you tried adding some ride height in the rear?  I would try that first unless your sag is way out of wack.  Maybe 2-3mm more on the ride height adjuster.

motomadness

zoner,

If the rear isn't hooking up, why would you tell him to add more ride height in the rear?  He may need to bring the front up for better weight transfer to the rear, or even lower the rear.

One thing:
Every track is different, so every setup will be different.  Expect that then be open to setup changes.

H-man

#4
Bsavoie, I'm a newbie myself who has read and been taught far better than I can execute so with that....

Have you tried standing the bike up sooner as your exiting the corner?  You may be doing this already so you know that by doing so, you will have a bigger tire diameter (less spin) and contact patch with which to make your drive.  Start standing the bike even before you complete the turn and climb back aboard.

H-man
Black Ops Racing
WERA/Fasttrax #42 (N)

"Life has a certain flavor for those who have fought and risked all that the sheltered and protected can never experience."  - John Stuart Mill

Super Dave

Bingo...

H-man wins.

Yeah, suspension can play a role.  Honestly, I doubt that anyone can tell you if your preload, spring rate, or dampening is correct via the internet.

I can usually ball park it in person...

But, honestly, most racers that don't have good dirt track experience focus too much on their corners with long radii that have high corner speed.  You can't put down any power 'cause, even with the SV, you've used up the traction.  You try to put small amounts of throttle down, and it doesn't hook up...you run out of space at the edge of the track.

Yeah, could be suspension, but execution is still a big player...

Here's a question...

Why would you think you need more preload?

Do you know what adding preload would accomplish?
Super Dave

watsonx11

Hey Dave,

  Why dont you explain what adding more preload will do.  I have been under the impression that if you pre-load is off then you could cause one of 2 thing.  To much preload and you eat your tire, not enough and your rear wheel will not hook up => cause rear wheel spin.  Now I am a newbie racer, and I am learning more all the time.  Please explain your question.


Super Dave

Well, ok, I teach schools to people that race...in addition to peopel that want to start racing.

So, I will restrict myself from just saying one thing or another.

If anyone wants to try answering questions I have, I'll make some statements.  

The flip side is one can go out and drop years of one's time, remain under employed with the aim to go out and race like I did and learn it all that way.

So....

QuoteTo much preload and you eat your tire, not enough and your rear wheel will not hook up => cause rear wheel spin.

Why would those things happen?  Define "too much preload"?

But we're back to the original question....What does preload do?  

Anyone, anyone?
Super Dave

tigerblade

QuoteBut we're back to the original question....What does preload do?  

Anyone, anyone?

I know but I spent some hard earned $$$ to find out, so I'm not tellin'.   ;D
Younger Oil Racing

The man with the $200K spine...

Super Dave

Quoteso I'm not tellin'.   ;D

Bingo!  
 ;D ;D

Super Dave

H-man

#10
I'll give 'er a shot :)  What have I got to lose except face and reputation ;D

"Preload", as we're using it here, is the force exerted on the spring while the bike is at rest.

I'm going to guess that many folk increase their preload thinking they'll create a stiffer spring (or at least have the allusion of a "stiffer" spring).  So under this presumtion, a rider will crank up the preload thinking it'll stop some rear wheel hopping or loss ot contact with the ground.

As to what is "too much preload", I'd say that's when you've increased the preload to the point that the bike's at, or beyond, the upper boundry of recommended free sag (5 mm I think.  We're talking about the rear wheel, right?).

The thing I can't figure out is why cranking up the preload doesn't give these folks a rough ride - less control - since I'd think they'd bottom out (or top out) easily.  Or more easily.

Then again, maybe they're thinking the increased preload will reduce the amount of squat when they accelerate, thus having most of the energy directed forward instead of forward and upward???

I'd better quit now. :-X

Cheers.
Your student   H-man

Black Ops Racing
WERA/Fasttrax #42 (N)

"Life has a certain flavor for those who have fought and risked all that the sheltered and protected can never experience."  - John Stuart Mill

Super Dave

QuoteI'll give 'er a shot :)  What have I got to lose except face and reputation ;D

"Preload", as we're using it here, is the force exerted on the spring while the bike is at rest.

I'm going to guess that many folk increase their preload thinking they'll create a stiffer spring (or at least have the allusion of a "stiffer" spring).  So under this presumtion, a rider will crank up the preload thinking it'll stop some rear wheel hopping or loss ot contact with the ground.

 

Nice job, H-Man...

Good.

Look at it this way.  More preload will not increase the spring rate.  You CAN preload it to a point where it spring binds.  That would increase the rate...kind of like replacing the spring with a strut...LOL!  You get the picture.

So, preload really changes ride height.  It doesn't change the rate, unless it's spring bound.  Might help how the tire wears because of weight transfer, etc.

It can be over done where the shock is topped out.

Really, you've got to try and start out with the correct spring.

And a reasonable and correct geometry.

Most bikes have linkages, so that comes into the mix.

Throw in a rising rate spring like I use and then the sag numbers that I use get compared to a straight rate spring are completely different.

More thoughts?
Super Dave

H-man

bsavoie, are you still out there?  Has any of this been useful?  Info overload maybe?

You say that your SV is sliding around?  You may wish to read the comments by ekraft at http://www.racemotorcycles.com/cgi-bin/board/YaBB.pl?board=tips;action=display;num=1091243911;start=.  Eddie's a pretty quick SV rider racing in WERA.  Your issue may be the same as he described.

Just tryin' ta help bra 8)
Later
  H-man
Black Ops Racing
WERA/Fasttrax #42 (N)

"Life has a certain flavor for those who have fought and risked all that the sheltered and protected can never experience."  - John Stuart Mill

Tunersricebowl

Try reducing the comp damping,it will let the weight transfer to the rear quicker.

fourandsix


Super Dave

QuoteI know but i'm not telling !

Yup, and the source to fix your problems...manufactured by the chassis or your own undoing...

http://4and6.com
Super Dave

Steviebee

QuoteI know but i'm not telling !

Great customer service !

Ridgeway

QuoteGreat customer service !

Well, are you their customer?  If so, I'm sure they'll be glad to help you out!
CCS Midwest EX #18
07 GSX-R600
03 SV650s

zoner

#18
motomadness

 Adding ride height in the rear promotes more swingarm angle therefore producing more antisquat.  His complaint is loosing grip when ON the gas exiting corners.

motomadness

zoner,

Why would more swingarm angle produce more anti-squat?  Yes, the geometry changes and the multiplication of the forces changes with geometry, but spring preload will probably have a bigger effect on anti-squat than simply changing the ride height 2-3 mm.  One would think that more rear ride height would allow more swingarm travel, not less.

What I learn at Pridmore's Star School was to reduce the time I had the bike leaned over, especially on the exits.  I think someone said this earlier - pick the bike up, while keeping your body off to the side will allow you to complete the turn and get on the fatter part of the tire = more grip.

Super Dave

Quotezoner,

Why would more swingarm angle produce more anti-squat?

Because it changes the relationship between the swingarm pivot, the rear axle, and the countershaft.  

Think about it.

You could have the exact same angle of the swingarm on any bike, but because of the relationship between the components...lower countershaft, longer distance from the pivot to the countershart or the rear axle...it's all related.

That's why building a really competitive bike is hard.  


Super Dave

motomadness

#21
I didn't deny that, I just don't think that alone will multiply the forces to make a significant difference in squat.  If 2-3 mm of shock ride height turn into 10-15 mm of swingarm pivot height, then I would agree more, but I don't think that's the case.

I think often times, we focus too much on the bike and not enough on the riding behavior.

Super Dave

You can get the ride height out of whack where it makes too much anti-squat.  

That was my problem on my GSXR600...dummy me, I wasn't using the GMD stuff from 4&6, but I do have some experience in bikes too.

Anyway, the trick is being able to recognize and determine what you need to do to the chassis.

Too much focus on the bike?  Never.

Too little on the rider?  Well, it's part of it.  The rider must execute reasonably.  You and I are not going to be able to do what Mladin does.  But, on the flip side, we may not be able to even ride his set up...back to the chassis.  

Is the bike hard to ride?  Are you tired?  Does it destroy tires when it shouldn't?  Bike.

I'll see you tomorrow, Sean... ;D
Super Dave

khanson

On a lighter note........

Buy a 1000....carry a lot of corner speed for an extended period of time....whack the throttle.....and enjoy your flight!!!!!!
Kevin Hanson<br /><br />www.SafetyFirstRacing.com<br />Safety First Racing<br />847.357.1309

zoner

motomadness:

I'm not saying the problem is with the ride height,  I am offering it as a possibility.  I agree with what you are saying about getting the bike "stood up" as soon as possible whole heartedly.  But unless you make changes and feel the results(good or bad) how will you ever know if it can be better.  Suspension shops can give you great baseline geometry setups,  but every rider is a little different on how they like there bike set up.  And if you think that 3mm might not make a feelable difference,  I would have to argue that point.  Just my s cents.

Super Dave

Quote...and enjoy your flight!!!!!!

You may feel mild discomfort.

Terms and conditions apply.

Your final APR might not reflect the current APR.
Super Dave

motomadness

zoner,

I think 3mm of ride height can be felt.  I've made those kinds of changes and felt a difference.  May argument was more related to the idea of anti-squat and what how does small amounts of ride height affect anti-squat.

Maybe an easier starting point is what is anti-squat?  Answer is spring motion terms.  What swingarm angle must you begin with?  What shock length must you begin with?

At some point, because of the way forces are multiplied, there would be some optimal adjustment range where the affects of adjustments have significant results, but outside or on the limits of that range, the affects are less noticeable.  I guess this is where GMD can get you closer to that range than merely seat of the pants trial and error.

Super Dave

QuoteWhat swingarm angle must you begin with?  What shock length must you begin with?

At some point, because of the way forces are multiplied, there would be some optimal adjustment range where the affects of adjustments have significant results, but outside or on the limits of that range, the affects are less noticeable.  I guess this is where GMD can get you closer to that range than merely seat of the pants trial and error.

What angle?

Really open question.

If you only take the angle as the determining factor, you've eliminated the length of the swingarm, for one.  That will affect how it all works.  Of course as the angle changes, so would trail and the like.  It's really a whole package.  So, what shock length would you start at?

Some suspension guys do have a "starting" point, but that's all it is.  Then it all goes back to trial and error.  That number might be based on one particular rider that they work with that prefers a particular set up.  Additionally, a particular tire, a particular modification to the fork, etc.

Some production motorcycles need dramatic changes to work in the correct fashion.  Those numbers can be ridiculous in one's eyes.

I've worked by myself trying to do things...and I've had decent results.  But I've also had the time to work with Jim at 4&6 having him do my stuff with the GMD system and then Hyperpro products.  My bike is very, very good...to say the least.  The refinement of my chassis is all about me really trying to find little things to whine about now...and about ME really riding harder and harder.  It's hard to really ride extraordinarily hard when the chassis isn't as good as it really should be.

Question always has to be:  How many tires, how many track days, how many races, and how much money will you sacrifice to try to make up for the simple opportunity to just get it done right?

Does it add value to the bike?  For me...LORD, yes!  
Super Dave

motomadness

I really like this discussion.  Sure would be nice if we had a data acq. system to play with.

tshowrench

Dont forget

What is the shock length?

At what length does the suspension come into the steep part of the curve?

Check your tire pressure?

What is your gearing?

What is your right wrist doing in relation to your lean angle?

Just thought  I would try to throw some more confusion in there....

Gixxerblade

#30
Read this.

INSANESTEVE777

I RIDE AN SV AND IF YOUR SLIDING THE REAR END YOU DOING SOMETHING WAY WRONG!!  THE IDEAL SWING ARM ANGLE IS 13 DEGREES,PRIDMORE SAID THAT REBOUND TIME IS A COUNT ...1 ONE THOUSAND,2 ONE THOUND,3 ONE THOUSAND AND IT COME TO A STOP WITH OUT BEING JERKY. THATS WHAT THEY SAID NOT ME.
  I SAY YOU SHOULD MAKE IT SOFT ALL AROUND AND START THERE. IF YOU HAVE TO BIG OF A SPRING IT WILL STEP OUT ON THE GAS. ON A FOX A 450 LB SPRING WILL WORK WITH A 180-220 RIDER WITH GEAR WEIGHT. IM HUGE AND IT WORKS FOR ME.
   I RODE EX500'S WHEN I STARTED RACING AND I WAS TOLD TO HIKE THE REAR UP...WAY UP. SO I DID AND THE REAR SLID OUT SO EASY IT WAS SILLY!!! SO THERE IS A TO FAR WHEN IT COMES TO RIDE HIEGHT
    SO I LEAVE YOU WITH THIS.....LEAVE IT SOFT FOR THE SPRING AND DONT BE AFRAID TO PLAY WITH THE SETTINGS ON THE CLICKER!!! YOU CAN ALWAYS GO BACK TO THE SLID SETTING !! HEHE

Super Dave

QuoteI RIDE AN SV AND IF YOUR SLIDING THE REAR END YOU DOING SOMETHING WAY WRONG!!  THE IDEAL SWING ARM ANGLE IS 13 DEGREES

Ok, this is naive.

First measure your swingarm angle.  Make it 13 degrees.

Next, change your gearing, and then make the angle 13 degrees.

How about pulling up the fork tubes 20mm then adjusting the rear ride height to make the swingarm 13 degrees.

That number has been floated around, but it's relationship between all the components that actually make a difference in the whole handling of the bike...its pretty much not relevant.

It might come up as a reasonable angle in some situations, but it is not the end all.  If that were the case, everyone could have a 13 degree swingarm angle and have a great handling chassis.

You think Mat Mladin has a swingarm that is the stock length?  How will that affect the swingarm angle by itself?

Go faster on an SV and it might be sliding also.  Until you reach that limit, there might be something more to be gained in one's riding and feel of the set up.
Super Dave

Thingy

 ;D ;D ;D

Dave, my 1000 keeps spinning up on me.   I found that if I set the swingarm angle at 13 degrees, don't lean it over very far, and only give it 1/3 throttle, it won't slide around at all.

Sorry, I shouldn't pick on a newbie...  ;)
-Bill Hitchcock
GP EX #13
Double Bravo Racing
'01 Ducati 748

Tuck your skirt in your panties and twist the throttle!

INSANESTEVE777

IF YOU READ WHAT I SAID,YOU'D SEE THAT I SAID THOSE NUMBERS ARE PRIDMORES NUMBERS AND NOT MINE!! BUT IF YOU DONT RACE THAN YOU SHOULDN'T TALK ABOUT SET UP. I READ ALL OF THE POST AND ALMOST NO ONE TOLD THIS GUY ANY NUMBERS. THEY TALKED ALOT OF THE SAME BLA BLA!! WHAT NUMBERS DID YOU TRY TO HELP OUT WITH???????? WOW YOUR FAST AND HELP FULL!! I WAS TRYING TO HELP AND IT SEEMS ALL YOU WANT TO DO IS TALK ABOUT HOW IT DOESNT WORK.
   I KNOW ALOT OF RACERS THAT ARE TO SLOW TO GET RACE TYRES UP TO TEMP,SO THEY HAVE TYRE PROBLEMS. I DIDN'T WANT TO COME ACROSS AS A A HOLE AND SAY "YOUR TO SLOW TO GET HEAT IN YOUR TYRES" BECAUSE THATS RUDE!! SET UP FOR CLUB RACERS ISN'T A BIG FACTOR. AT AMA LEVEL YES, MAYBE IF YOUR A FRONT RUNNER IN THE CLUB RACES AND THATS A BIG MAYBE.
  THERES ALOT OF FACTORS AND WITH OUT BEING NEXT TO THE BIKE ITS HARD TO SAY WHAT IT NEEDS. WHAT BIKE DID THE SHOCK COME OFF OF? THE LENGTH OF IT? HIS WEIGHT AND SIZE OF SPRING? TRACK TIMES,IS HE FAST,CAN IT BE NO HEAT IN THE TYRES? THERE IS TO MANY VERIABLES. SO PLEASE EITHER HELP OR TALK ABOUT SOME THING YOU DO KNOW!
    R1 HAS 13 DEGREES STOCK
    A 02 GSXR 750 RACE BIKE I ROAD ON THE TRACK  HAD 15 DEGREES ON THE SWING ARM
    MY R1 HAS 14.5
    I WAS ONLY GIVING A STARTING POINT TO WORK WITH!! THE MAIN THING TO GET RIGHT IS THROTLE CONTROL.  SO THE RACER WITH THE 1000 AT 1/3 THROTLE IS GOING IN THE RIGHT DERECTION!!! HE'S FAST!!  I'D TRY TO LEAN IT OVER A LITTLE MORE,BUT YOU MIGHT NOT HAVE THE SKILL TO HEAT UP THOSE TYRES!!