Track Tac

I hear "Forward Bite" a lot, what is it?

paulkish

paulkish

old fart
I'm not sure I understand "forward bite". I'm going to try posting about it to see if others agree with me or will tell me where and why I'm thinking wrong about it.

I wrote a reply using ideas about it in another thread and I copied them here and added to it. I'm hoping for a, "yeah I think your right about it" or "your close but here's where you go a stray" or "your totally wrong and this is the way it is". ... :)

thanks in advance


paul

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Forward bite is only an issue once acceleration starts, somewhere from mid corner on. My theory explains the normal use of the rear tires on a staggered solid axle, because each rear tire has a different surface speed.

It goes you need to load or have the LR loaded going in so it can act as an anchor while your normally slowing down and doing your turning in towards the middle of the corner. You then complete both the slowing down and turning your going to do going into the corner. And you usually try to do it traveling up the bank of the track storing energy for up coming acceleration. This can only occur because the RR tire is larger and it's surface speed is faster then the LR tire's surface speed.

You will then if possible will roll the corner some after slightly accelerating above your entry speed, in as close to an arc as possible. Doing so will allow you to maintain a speed slightly above entry; or you will immediately begin your acceleration to exit. Forward bite on track problems only occur after acceleration starts.

The fix I understand when there is a "forward bite" on track problem, is so you can apply more acceleration without pushing.

I think forward bite problems are not generally about having too much weight and grip on the LR, but about not enough weight and grip on the RR, to cause it to be able to out accelerate the LR as needed.

I say "as needed" because if you get too much acceleration out of the RR, then the same problem can occur except it's because of the RR wanting to go straight and not being able to made to turn by the front tires.

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A push mid corner out is usually all about not having enough bite at the RR. The fix usually involves taking something away from the LR. But you do not have to take anything away from the LR to fix it, if you can get enough bite put into the RR to cause it to out accelerate the LR.

I have to add here that this is all available grip and available hp dependent. You will never have unlimited grip and unlimited hp and you will always be at the limit of both hp and grip or needing more of one or the other. And since you can never have both rear tires gripping unless your stagger combined with slip ratio and slip angle, happens to exactly match the radius of the track, one tire or the other or both must always be slipping. That means with a staggered solid axle it's generally a given that one tire or the other must be slipping and all your setup is to control when each grips and slips. If they are both slipping then it's about controlling and maximizing the slip ratios of each, to make the axle roll in the direction you want to go.

From mid corner out after you start acceleration it's about being able to move enough weight or apply enough weight to the RR, so it's larger diameter can out accelerate the LR. If you don't get enough weight and grip on the RR so it can, then it will push because forward bite from the LR, will make it go straighter then you want to go.

The net of this is if you can get enough grip out of the fronts to over come the excessive forward bite from the rear, it eats HP and speed mid corner off. If you can't then it pushes and it eats speed because you have to slow down or drift out too much, or hit the wall.
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I'm adding this to the end of my thoughts to help those who come from the "real race car" world, to understand the difference in our LTO world. I think in my above writing if you would replace the RR being able to out accelerate the LR, with unloading the inside rear it would read about fixing over steer mid corner out. The major difference between LTO and "real race cars" is in the ability to cause the RR to out accelerate the LR. "Real race cars" do not have that ability. If you come from the "real race car" world and cannot comprehend the possibility of the "outside rear" out accelerating the "inside rear", you cannot understand LTO's.

thanks for reading and I hope to get feed back ... :)


paul
 
Forward Bite: the ability of the driven tires at their optimum temperature and adhesion level to accelerate a vehicle. AKA optimizing the available grip for any given situation while accelerating.

Now some people may use this term to describe any number of problems and in essence they are trying to convey that they aren't capable of carrying speed from the entrance of a corner to the exit of a corner in LTO terms. So in essence the term is thrown around and not used for it's intended meaning as any number of problems can cause ones kart not to carry speed through a corner and they may have nothing to do with the available grip from the tires to give forward bite. most of the time it's a setup issue causing a kart not to carry moment on exits.
 
apex96 said:
Forward Bite: the ability of the driven tires at their optimum temperature and adhesion level to accelerate a vehicle. AKA optimizing the available grip for any given situation while accelerating.

Now some people may use this term to describe any number of problems and in essence they are trying to convey that they aren't capable of carrying speed from the entrance of a corner to the exit of a corner in LTO terms. So in essence the term is thrown around and not used for it's intended meaning as any number of problems can cause ones kart not to carry speed through a corner and they may have nothing to do with the available grip from the tires to give forward bite. most of the time it's a setup issue causing a kart not to carry moment on exits.
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Are you saying you can't turn going into the corner either, without forward bite being there to push you around the turn? Thanks and if you are saying it, I can easily fit it into my thinking.

thank you


paul
 
think of it as forward grip, if you didn't have forward grip you wouldn't move at all. bite and grip are really the same thing it's just that some people think of the different variations in compounds as different levels of grip where as the compounds are just different durometer numbers and they can either give better grip/bite or worse grip/bite ( ex: over heating a compound). then we have chemicals to enhance the grip of the compounds (bite enhancers) and chemicals to change the duromter reading of a compound (softeners). So yes you have to have forward bite all around the track to make lap times.
 
Not over-thinking, just giving an enhanced explanation with some simple examples. It's easy for those of us still currently active in the sport to understand whats happening, it's much tougher to try to explain it to others who view the sport from the comfort of there recliners on a PC (not saying they weren't active in the sport some years ago but have since been left by the wayside due to time and progress)
 
I agree that it is not overthinking, just refining the details - many things are simple on the surface (including forward bite), but rapidly get more complicated when you bore down into the details of on-track application. Our general feeling on forward bite in turns is that most problems on that part of the track come from "timing" - which rear tire is the dominant tire bite-wise where in the turn. Dealing with timing on a kart is a little more difficult than on cars with a suspension as the adjustments for loading and unloading the LR and when that occurs are more subtle and hence less dramatic in both immediately felt effect and the magnitude of that effect than on, say, a sprint car. With cars with springs (type of spring isn't critical to this disussion) and shocks things are easier - basically spring rate determines the amount of weight that transfers and shock damping choices control the timing of that transfer. Without shock damping rates to play with, weight transfer timing gets a bit tougher to change significantly. My personal simplification on karts is not to think about the detail implications of forward bite and which rear tire has more bite when in the turn (other than which tire is most likely under or overloaded to be the cause of the problem), but to simply go with the standard karting approaches to setup used to cure loose or tight situations at a specific portion of the turn by curing that under or overload situation, not worrying too much about exactly what is happening with each individual rear tire at any specific moment with regard to forward bite, though an understanding of those dynamics can assist in refining your setup once you get close.
 
Outrider said:
I agree that it is not overthinking, just refining the details - many things are simple on the surface (including forward bite), but rapidly get more complicated when you bore down into the details of on-track application. Our general feeling on forward bite in turns is that most problems on that part of the track come from "timing" - which rear tire is the dominant tire bite-wise where in the turn. Dealing with timing on a kart is a little more difficult than on cars with a suspension as the adjustments for loading and unloading the LR and when that occurs are more subtle and hence less dramatic in both immediately felt effect and the magnitude of that effect than on, say, a sprint car. With cars with springs (type of spring isn't critical to this disussion) and shocks are easier - spring rate determines the amount of weight that transfers and shock damping choices control the timing of that transfer. Without shock damping rates to play with, weight transfer timing gets a bit tougher to change significantly. My personal simplification on karts is not to think about the detail implications of forward bite and which rear tire has more bite when in the turn, but to simply go with the standard karting approaches to setup used to cure loose or tight situations at a specific portion of the turn, not worrying too much about exactly what is happening with each individual rear tire at any moment with regard to forward bight, though an understanding of those dynamics can assist in refining your setup once you get close.
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Youre dealing more with weight transfer than you are forward bite. You can still have all the weight transfer in the world and be low on forward bite, 2 different subjects IMO.
 
I' m no pro. don't know what yall talking about up there.. I have a problem, going into the corner is ok. mid to getting out of the corner it pushes up the track. have to turn full steer and sometime that's not enough ..............Thanks .....please don't tell me about forward or backward bite because I do not know what you talking about...................
 
Lake said:
I' m no pro. don't know what yall talking about up there.. I have a problem, going into the corner is ok. mid to getting out of the corner it pushes up the track. have to turn full steer and sometime that's not enough ..............Thanks .....please don't tell me about forward or backward bite because I do not know what you talking about...................
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Ok, I don't care if I started this to talk about forward bite or not. Trying to help others and giving it a shot trying to help you is IMHO, what this place is all about. {except for maybe it's more about selling and buying stuff. ... :) }

No matter what your pushing because your back tires are making your kart go straighter then you want to and you can't over come it by turning the front tires. If you could over come it by turning the front tires, you'd be telling us it handles just fine but it's a total pig coming off the corner. Or we'd expect you to be saying everyone is kicking your butt towards the end of the straight.

To be fast no matter what you race, the momentum you carry into the center of the corner, decides how much faster the power you then apply mid corner out will make you. Being fast IMHO is about being able to carry the most momentum in towards the center of the corner and then slightly accelerating and maintaining the slight acceleration to a point, where it will put you on a line that you can take the best advantage of final acceleration on down the straight.

In a nut shell, it's maintain maximum momentum going in and then get to a point for the best acceleration down the straight, as quick as possible, making the straights as long as possible and the turns as short as possible.
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>>>>> To help out and I think for others to help out, to help fix your problem we have to figure out if both tires are making you go straighter they you want to, or is it the right or the left doing it?

Throw numbers at us and we might be able to see from the numbers what or which tire is over powering the front tires, making you go straight when you want to turn. Or maybe you can help us out from the seat of your pants, on which rear tire you feel is driving so hard you can over come it by turning the wheel. Can you help us out a little by throwing some more info at us? please?

paul
 
But, won't having proper weight transfer (correct timing) insure that you are getting the maximum forward bite available for the tires you are running? No bite will always be no bite of course. I think this is a good thread with maybe some great insight soon to come to the surface. Please continue!

DD
 
DirtyDan said:
But, won't having proper weight transfer (correct timing) insure that you are getting the maximum forward bite available for the tires you are running? No bite will always be no bite of course. I think this is a good thread with maybe some great insight soon to come to the surface. Please continue!

DD
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Dan, IMHO if you use a staggered solid axle, what your thinking about and asking about IS what all setup is about.

I think in the past on here and now I correctly define what is the ideal way to use a staggered solid axle, based on the difference in rear tire surface speed. The rest is about on track problems and things which can and do prevent you from using it in the ideal way.

I like to say it's that simple and it is that simple. But all the variables involved being able to use your staggered solid axle in the ideal way I describe, makes the total picture very complex. Complex is not necessarily complicated, if you understand the individual parts involved.

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hey Dan, how come yer always looking over your left shoulder... you fraid someone's going to get under you racin, DD ? ... :)
 
paulkish said:
hey Dan, how come yer always looking over your left shoulder... you fraid someone's going to get under you racin, DD ? ... :)
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Hmmmm. I injured my neck as a child and that's as far straight forward as I can turn my head....

Or, it's easier than looking over my right shoulder....

Or, I found that that position gives me optimum forward bite out of the turns silly!

Or, I'm looking for a drone....

Or, honestly, I never look over my shoulder - must have me confused with somebody else...

But I do enjoy your posts! Keep it up Paul.

DD
 
I always thought of forward bite from just after center off the turn, to 1/4 the length of the straightaway. If I could pass coming off the corner, I had better forward bite than the other guy.

Turning in to center, I would describe that as "turning well". But, that's just me and how I communicated with my crew.
 
I've often thought of forward bite as part of a 3 stage process. Front grip on entry, sidebite/preload of rear tires in the middle, and forward grip from center to exit of corner.
 
Sickle Hill Kartway said:
I always referred to forward bite as Traction that keeps you moving in a forward motion. Nothing more, nothing less.
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That's a broad but I think correct statement. As I stated in my previous post, I think forward bite/grip is part of a 3 part process. I always look at it as an obtuse triangle. Draw a line from the left rear, to the right front, to the right rear and back across to the left rear.

On entry you have load transfer from your left rear to your right front and even some into your left front which equates to your front grip for steering on entry.

In the center some of your right front weight transfers into the right rear from centrifugal force. Just before direct middle of corner you start to preload your rear tires.

Once after center your rear tires are sharing an equal grip load to propel you off the corner.

In my opinion, that theory is shared for any type of race vehicle, from a kart, to micro sprint cars, to sprint cars, stock cars etc. What changes is when you want to apply what happens. With bigger cars it's all based off of your shocks which control the timing of weight/grip to a given corner of a race car.


By the way paul, I really enjoy your posts on here. It gets my brain thinking of ways to help improve our own program.
 
The-Hawk7 said:
That's a broad but I think correct statement. As I stated in my previous post, I think forward bite/grip is part of a 3 part process. I always look at it as an obtuse triangle. Draw a line from the left rear, to the right front, to the right rear and back across to the left rear.

On entry you have load transfer from your left rear to your right front and even some into your left front which equates to your front grip for steering on entry.

In the center some of your right front weight transfers into the right rear from centrifugal force. Just before direct middle of corner you start to preload your rear tires.

Once after center your rear tires are sharing an equal grip load to propel you off the corner.

In my opinion, that theory is shared for any type of race vehicle, from a kart, to micro sprint cars, to sprint cars, stock cars etc. What changes is when you want to apply what happens. With bigger cars it's all based off of your shocks which control the timing of weight/grip to a given corner of a race car.


By the way paul, I really enjoy your posts on here. It gets my brain thinking of ways to help improve our own program.
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In kart racing centripetal forces are applied.
 
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