Could a "heavy" racer win?

[p.dath]

I'm completely naive about racing, not having any knowledge about it at all.

I've been trying to learn more about tyres recently. The subject complexity greatly exceeds my abilities.

One thing I have learned though is that tyre traction is greatly related to "weight".

This got me thinking; a lot of effort goes into making motorbikes lighter for greater acceleration - but this must come at the cost of reduced traction.

If a 1000cc bike is being ridden so that it is constantly breaking traction on the track; then perhaps the rider would be better to actually make the bike heavier again, as more traction would surely result in greater acceleration. Otherwise it seems to me that you just have more power than you are able to use.

[Edbear]

I think the fact that bikes are getting lighter, more powerful and yet faster to accelerate every year, may indicate that traction isn't all about weight, but as much about suspension, gearing and tyres as anything else. Weight distribution has more to do with it than weight per se.

[FJRider]

Rider ability accounts for a lot ... Robert Holden was reknown for riding "non-competitive" bikes to race wins ...

Big balls and no fear helps ... but it's ability that counts ... on the day ...

[DEATH_INC.]

It's exactly the opposite, lighter is better. As long as you can generate enough heat into the tyre for it to work properly.
Ask anyone that knows how to set up a good circuit car, the wheel with the most load on it breaks traction first.

[lostinflyz]

racing is about weight transfer much more so than actual weight. A bike is steered into the corner with alot of weight on the front wheel (braking you can be near 100% weight on the front). As you gas the bike back up to shoot out, you rapidly transfer weight rearward. The control of that weight transfer is one of the big keys to traction. The same applies from accelerating to braking in reverse.

If your bike was 10 tonne (all over the rear axle) it still would be no good if your rear shock was a steel rod (or a pogo stick)

[schrodingers cat]

Good question and the answers so far show how little folks understand about tyres.

Tyre grip is generated in two ways. One is pure mechanical 'interlocking' with the road surface. The second is at a molecular level - bonding to the road and having the bond broken.
Tyres are designed to work in a heat range. Within that range the compound softens to allow the rubber to 'flow' and mould to the road (mechanical grip) and the molecular action is enhanced.

If there is dust/pollen etc on the road the tyre happily sticks to the dust and relies solely on mechanical grip to get the job done resulting in a reduction of overall grip.
Water works against both mechanical and molecular grip

The rubber contains aromatics and overheating 'burns' excessive amounts of the solvents etc out. Evidence of this is the 'bluing' you see of a tyre that has had a beat up.

Leaving a tyre sitting for too long, esp exposed to UV evaporates all the goodies.

Green (new) rubber is in its optimum state. Each time the rubber heats and cools it hardens - hence the term 'heat cycles'

Tyres are load sensitive. The more load, the more grip.
Except the trend isn't linear. Double the load doesn't equal double the grip unfortunately and extra mass has to be accelerated and decelarated.

More grip = more heat and the total loading is the limitation on how soft the compound can be. The lighter the loading the softer it can be. Since water cools the rubber, rain tyres are much softer than dry.

So the short answer is no - if there were two riders of identical ability riding the same machine, the lighter one would have a performance advantage.

However, for all the theory to make a scrap of difference the riders would have to load and unload the tyres appropriately at the maximum availible traction (ie be a perfect rider)

For blokes at clubby level the truth is a blurred. New tyres feel great. Do they make you faster?
Often your lap time is dictated by your head not your arse.
Does the new tyre give you a very short peak and then back to same old same o?
In that case your bike settings/riding syle/technique etc aren't in sync and you are burning the tyre to get a very short lived gain.
The trick is going as fast as you can and keeping the machinery good

[marty]

if your bike/rider combo weighs 250kg, and you are at rest, you weigh 250kg. as soon as you accelerate, either forward, around a corner or in braking, that weight is compounded (by G-force) - so for example at 1.5 G, you have an apparant weight of 375kg, an increase of 125kg. If you weigh 200kg, at 1.5G, you 'weigh' 300kg, an increase of only 100kg. Higher the force (actually the acceleration) the bigger the difference gets. I used to do a lot of high-energy aerobatics, and weighing 100kg hurt a lot more than weighing 90kg that's for sure! Further, increased weight means more friction, greater mass to shift direction - more momentum in the direction you are going, so more force required to shift it!

[gixerracer]

Im phater and heavier than probably most in the NZSBK class and I still managed a win at Manfeild nats and it is meant to be a power track so I would say it means sweet F A:killingme

[Shaun]

Good question and the answers so far show how little folks understand about tyres.

Tyre grip is generated in two ways. One is pure mechanical 'interlocking' with the road surface. The second is at a molecular level - bonding to the road and having the bond broken.
Tyres are designed to work in a heat range. Within that range the compound softens to allow the rubber to 'flow' and mould to the road (mechanical grip) and the molecular action is enhanced.

If there is dust/pollen etc on the road the tyre happily sticks to the dust and relies solely on mechanical grip to get the job done resulting in a reduction of overall grip.
Water works against both mechanical and molecular grip

The rubber contains aromatics and overheating 'burns' excessive amounts of the solvents etc out. Evidence of this is the 'bluing' you see of a tyre that has had a beat up.

Leaving a tyre sitting for too long, esp exposed to UV evaporates all the goodies.

Green (new) rubber is in its optimum state. Each time the rubber heats and cools it hardens - hence the term 'heat cycles'

Tyres are load sensitive. The more load, the more grip.
Except the trend isn't linear. Double the load doesn't equal double the grip unfortunatly and extra mass has to be accelerated and decelarated.

More grip = more heat and the total loading is the limitation on how soft the compound can be. The lighter the loading and softer is can be. Since water cools the rubber rain tyres and much softer than dry.

So the short answer is no - if their were two rider of identical ability riding the same machine the lighter one would have a performance advantage.

However, for all the theory to make a scrap of difference the riders would have to load and unload the tyres appropriately at the maximum traction (ie be a perfect rider)

For blokes at clubby level the truth is a lot more blurred. New tyres feel great. Do they make you faster? Often your lap time is dictated by your head not your arse.
Does the new tyre give you a very short peak and then back to same old same o? In that case your bike settings/riding syle/technique etc aren't in sync and you are burning the tyre to get a very short lived gain. The trick is going as fast as you can and keeping the machinery good



Very very well explained man

[schrodingers cat]

It's exactly the opposite, lighter is better. As long as you can generate enough heat into the tyre for it to work properly.

Correct


Ask anyone that knows how to set up a good circuit car, the wheel with the most load on it breaks traction first.

Not entirely correct. During braking and acceleration (Longitudinal G) the most lightly loaded tyre breaks traction first ie inside wheel locking under brakes during corner entry

During cornering (Lateral G) the tyre at the end of the car that becomes 'oversaturated' (overloaded) loses grip relative to the other end

Tyres develop grip due to a distortion of the contact patch refered to as 'slip angle'. Essentially the difference between where the wheel is pointed and where it is actually taking you. Maximum grip is developed at around 10% slip. The ability to 'feel' the tyre disappears at around 7%

Therein lies the difference between the good and the great

[roadracingoldfart]

Im phater and heavier than probably most in the NZSBK class and I still managed a win at Manfeild nats and it is meant to be a power track so I would say it means sweet F A:killingme


And being weight biassed isnt always the reason some riders fall off either , ...... aye !!:lol::killingme

[Kickaha]

Im phater and heavier than probably most in the NZSBK class

Who ate all the pies?
Who ate all the pies?
You fat bastard Craig,
You fat bastard Craig,
You ate all the pies!

[gixerracer]

Who ate all the pies?
Who ate all the pies?
You fat bastard Craig,
You fat bastard Craig,
You ate all the pies!

And then i won the race. Could pies be the new breakfast of champions?
I THINK SO :beer:

[Str8 Jacket]

Could pies be the new breakfast of champions?
I THINK SO :beer:

Hell, yes!

[DEATH_INC.]

Correct



Not entirely correct. During braking and acceleration (Longitudinal G) the most lightly loaded tyre breaks traction first ie inside wheel locking under brakes during corner entry

During cornering (Lateral G) the tyre at the end of the car that becomes 'oversaturated' (overloaded) loses grip relative to the other end

Tyres develop grip due to a distortion of the contact patch refered to as 'slip angle'. Essentially the difference between where the wheel is pointed and where it is actually taking you. Maximum grip is developed at around 10% slip. The ability to 'feel' the tyre disappears at around 7%

Therein lies the difference between the good and the great

Ah.....yeh. There is a point either way where it all changes. I was trying to keep it too simple :D

[yod]

fuck me.

who knew cats were so knowledgeable!?

[Kickaha]

who knew cats were so knowledgeable!?

That would depend on whether the cat is dead or alive

[yod]

That would depend on whether the cat is dead or alive

oh don't even start.....

[schrodingers cat]

That would depend on whether the cat is dead or alive

Depends if the cat is trolling or not...

[racer40]

Dave Jefferies was a big bugger, & he won a heap of IOM TT races.

[SWERVE]

And a guy by the name of Chris Hannan from the UK held the world wheelie/speed record for a few yrs in the 90,s
He was over 20 stone (280lb) someone will do the kg conversion.
His motto... heavy rider.....more horsepower................. i know its a different type of bike /set up but the big guy was (and still is ) a legend.
If you search that name on the net it will un-earth some pics of him on his nitro harley top fuel bike...... he hasn,t been going to Jenny Craig recently either.

[javawocky]

I'm surprised Nick hasn't weighed in yet :shutup:

[Crasherfromwayback]

Could pies be the new breakfast of champions?


Fur pies. And I'm a munching Champ.

[Robert Taylor]

Add in rider height as well.
A light rider will allow the bike to accelerate faster and will reach terminal speed sooner. The heavier rider will reach the same terminal speed , albeit a little later.
On a Superbike weight transfer to assist in the chassis attitude at any given point becomes more of an issue. This is where taller and slightly heavier riders arguably can have an advantage as they can move their weight around a lot more than a vertically disadvantaged rider. E.g moving their body backwards under braking, forward to help suppress wheelies off the turns etc.
Percentage of tyre slip etc is reasonably well documented on the net and in other forms. Tyre temperature is also another biggie and in fact its a HUGE issue here because we race so much in the winter months. When the temperatures ( ambient and track ) are in single digit to low two digit the bikes can often come off the track colder than when they entered the track straight off the tyre warmers. Personally I have been recording track and tyre temperatures a lot recently and when the track temperature drops the reduction in tyre temperature appears to be ''parabolic''
Many variables come into play, but its about getting temperature into the tyres and maintaining that as much as possible. That is the major preoccupation. How do you do that in winter months? Within sensible limits its often a combination of lower tyre pressures, firmer springing and / or firmer internal valving. All to make the tyre work harder and generate heat.

[neil_cb125t]

Well i can happily say im one of the more heavier guys out there - im 92kgs after a hard game of squash - add my riding gear, and a weekend on the booze and id hate to think!

This year ive gone back to my roots so to speak getting on a RG150 You'd think riding a street stock bike it might show?

Well i think in the dry its does make a difference, the guys that put in laps under the 1:29 at manfeild short on a RG150 never seem to be bigger than jockeys - weighing 60kgs or less.... Billy must be 60kg in gear wet!

BUT

Manfeild long VMCC round 2 the fat old bastard (me) started from the back of the grid or in pit lane could make it to front of the class in a few laps, in the RAIN. I think my weight is an advantage in the wet - don't know how technically, possibly the way i move on the bike (slowly!)gives me a better sense of grip in the wet. Or the weight is distrubted meaning the overall weight dist is more stable in the rain.

I know I've spent thousands ( and spending MORE ) on removing weight from my bike - it would be cheaper for me to be 60kgs.

[gixerracer]

Add in rider height as well.
A light rider will allow the bike to accelerate faster and will reach terminal speed sooner. The heavier rider will reach the same terminal speed , albeit a little later.
On a Superbike weight transfer to assist in the chassis attitude at any given point becomes more of an issue. This is where taller and slightly heavier riders arguably can have an advantage as they can move their weight around a lot more than a vertically disadvantaged rider. E.g moving their body backwards under braking, forward to help suppress wheelies off the turns etc.
Percentage of tyre slip etc is reasonably well documented on the net and in other forms. Tyre temperature is also another biggie and in fact its a HUGE issue here because we race so much in the winter months. When the temperatures ( ambient and track ) are in single digit to low two digit the bikes can often come off the track colder than when they entered the track straight off the tyre warmers. Personally I have been recording track and tyre temperatures a lot recently and when the track temperature drops the reduction in tyre temperature appears to be ''parabolic''
Many variables come into play, but its about getting temperature into the tyres and maintaining that as much as possible. That is the major preoccupation. How do you do that in winter months? Within sensible limits its often a combination of lower tyre pressures, firmer springing and / or firmer internal valving. All to make the tyre work harder and generate heat.

Shut up Robert you just wrecked another thread.

[roadracingoldfart]

Add in rider height as well.
A light rider will allow the bike to accelerate faster and will reach terminal speed sooner. The heavier rider will reach the same terminal speed , albeit a little later.
On a Superbike weight transfer to assist in the chassis attitude at any given point becomes more of an issue. This is where taller and slightly heavier riders arguably can have an advantage as they can move their weight around a lot more than a vertically disadvantaged rider. E.g moving their body backwards under braking, forward to help suppress wheelies off the turns etc.
.

So # 21 should eat more pies than he does (like he used to) , # 56 needs to be streched and eat no more pies than presently consumed , #47 needs to eat more pies than # 21 & # 56 , and then all will be even ???? Is it really that simple Robert ?

[roadracingoldfart]

Well i can happily say im one of the more heavier guys out there - im 92kgs after a hard game of squash - add my riding gear, and a weekend on the booze and id hate to think!

Manfeild long VMCC round 2 the fat old bastard (me) started from the back of the grid or in pit lane could make it to front of the class in a few laps, in the RAIN. I think my weight is an advantage in the wet - don't know how technically, possibly the way i move on the bike (slowly!)gives me a better sense of grip in the wet. Or the weight is distrubted meaning the overall weight dist is more stable in the rain.

I know I've spent thousands ( and spending MORE ) on removing weight from my bike - it would be cheaper for me to be 60kgs.

Your just a fat bastard , you only wiegh what you do to push me around and you go so fast in the wet cause your a bloody idiot , Ohhh and as for the old bastard bit , bugger off . thats me.



Shut up Robert you just wrecked another thread.

Too close to home on the pie front Craig. ????

[pete376403]

Rossi weighs 59kgs - lack of weight doesn't seem to hold him back

[jaffaonajappa]

Rossi weighs 59kgs - lack of weight doesn't seem to hold him back

Hmmm.....recent races. 'Somethings' holding him back....
But yeah ok, its unlikely to suddenly be his weight thats slowed down the Dr.

[Robert Taylor]

Hmmm.....recent races. 'Somethings' holding him back....
But yeah ok, its unlikely to suddenly be his weight thats slowed down the Dr.

No longer being on a Yamaha is a major cause.....................

[FROSTY]

I keep thinking of an old auckland club champ--Bubbles grey. He was a fairly large chap yet stil wone a race or three

[quickbuck]

Well i can happily say im one of the more heavier guys out there - im 92kgs after a hard game of squash - add my riding gear, and a weekend on the booze and id hate to think!



Ya bloody feather weight.....
After burning 700 KCalories 3 times per week at the Gym, I am still over the tonne, with shoes on..... (they do weigh 600 gramms)..... Of course, muscle weighs 3 times what fat does... ;)

[Moooools]

Stuff molecular level bonding and tyre heat. How about some plain old physics?

A heavy rider takes more force to accelerate at the same rate. This force has to come from the tyre friction on the track. They have more friction due to the extra weight, but also need more friction to accelerate.

Same goes for breaking.

Cornering also requires a friction force from the tires acting towards the centre of the corner. This increased with increased weight. The same principle of more friction and more weight applies.

I won't do the equations but I can tell you that the equations for how fast a rider can accelerate, brake or corner without losing traction will not be related to mass.

This does not mean that heavier the same as lighter in all situations, just that a all riders experience the same amount of grip. Unless they are crap.

[Robert Taylor]

Ya bloody feather weight.....
After burning 700 KCalories 3 times per week at the Gym, I am still over the tonne, with shoes on..... (they do weigh 600 gramms)..... Of course, muscle weighs 3 times what fat does... ;)

Well at least its a no brainer that Air Force ( or what passes for it after Helens ghastly purge ) are faster than grunts or those from the ''senior'' service.

[gixerracer]

Stuff molecular level bonding and tyre heat. How about some plain old physics?

A heavy rider takes more force to accelerate at the same rate. This force has to come from the tyre friction on the track. They have more friction due to the extra weight, but also need more friction to accelerate.

Same goes for breaking.

Cornering also requires a friction force from the tires acting towards the centre of the corner. This increased with increased weight. The same principle of more friction and more weight applies.

I won't do the equations but I can tell you that the equations for how fast a rider can accelerate, brake or corner without losing traction will not be related to mass.

This does not mean that heavier the same as lighter in all situations, just that a all riders experience the same amount of grip. Unless they are crap.

All riders experience the same amount of grip???? BOLLOCKS
Has nothing to do with many things listed so far comes down to what tyres they are using what compound that tyre is and what pressures they are running and also how well they bike is set up

[schrodingers cat]

Stuff molecular level bonding and tyre heat. How about some plain old physics?


I won't do the equations but I can tell you that the equations for how fast a rider can accelerate, brake or corner without losing traction will not be related to mass.


Force = Mass x Acceleration.

So, FAIL.

Unless you have found a way past the 2nd law of motion...

[Shaun]

All riders experience the same amount of grip???? BOLLOCKS
Has nothing to do with many things listed so far comes down to what tyres they are using what compound that tyre is and what pressures they are running and also how well they bike is set up

Proffessional test rider job coming your way dude

[davebullet]

This thread is USELESS without pics!..

"rider sag" anyone?

<img src="http://www.nahblog.com/wp-content/uploads/2010/04/fat_biker_1.jpg">

[Shaun]

This thread is USELESS without pics!..

"rider sag" anyone?

<img src="http://www.nahblog.com/wp-content/uploads/2010/04/fat_biker_1.jpg">



ha, looks like this guy is using the NEW TYRE Profile of 120-0-17 front 180-0 17 rear

[Matt Bleck]

ummmm hasn't Nick Cole won a 600cc NZ championship? :facepalm:

[Shaun]

ummmm hasn't Nick Cole won a 600cc NZ championship? :facepalm:



Yes But he is now about 20KG; less than he used to be 2 or so years ago

[jellywrestler]

ummmm hasn't Nick Cole won a 600cc NZ championship? :facepalm:So did Jared Gillard who from memory was 100kg and 6foot five at the time

[Crasherfromwayback]

So did Jared Gillard who from memory was 100kg and 6foot five at the time

Did that ginga wilderbeast finally win a 600 title? Good show if he did.

[Shaun]

So did Jared Gillard who from memory was 100kg and 6foot five at the time

Jared was at least that size, and rode bloody awsome

[wharfy]

Jared was at least that size, and rode bloody awsome

Stop it you guy's me being 95 kilo's is not going to be an excuse for being crap if you keep this up !
(Ginger Molloy has already fucked the being old as an excuse for being crap)

[SWERVE]

ha, looks like this guy is using the NEW TYRE Profile of 120-0-17 front 180-0 17 rear

caption:
Its ok little guy.... just stay still in there untill we get past the gate... then you can come out.
The lengths some will go to get in to a meeting free...eh:facepalm:

[Robert Taylor]

ummmm hasn't Nick Cole won a 600cc NZ championship? :facepalm:

2 alternative Nick Coles, in all respects the same but one is 110kg and the other is 90kg. 2 green Kawasakis both exactly the same except one is set up for 110kg Nick Cole and the other is set up for 90kg Nick Cole.
Who is going to lap faster?

[Latte]

2 alternative Nick Coles, in all respects the same but one is 110kg and the other is 90kg. 2 green Kawasakis both exactly the same except one is set up for 110kg Nick Cole and the other is set up for 90kg Nick Cole.
Who is going to lap faster?

The one that realises... there is no spoon.

[Moooools]

Force = Mass x Acceleration.

So, FAIL.

Unless you have found a way past the 2nd law of motion...

That's cute. But the second law of motion more closely states that the change is momentum is related to force x time.

Right now I am thinking that "Schrodingers cat" must be one of those ironic names...

If you had bothered to read all of it you may have understood. Or maybe not, perhaps there is no hope for you. I will however persevere.

Here is are the equations FOR THE CORNERING ASPECT:

F = ma
a(acceleration towards the centre of the corner) = v^2(velocity squared)/r(radius)

So if you combine the two... F(acrossways) = mv^2/r This is the force required by the tires to maintain circular motion.

The maximum corner speed is when this force is equal to the maximum force that the tires can exert without slipping. This is given by:

F(acrossways) = k(friction constant of the tyre)x F(downwards)

F(downwards) = m(mass) x g(gravity)

Sooo.... F(acrossways) = k x m x g

Now we make the two equations equal to each other.

k x m x g = mv^2/r You will notice that there is an m on each side, representing mass(of rider and bike). These can be cancelled off.

Sooo.... k x g = v^2/r

v = Squareroot(k x g x r)

The v above is the maximum speed a bike can travel around a corner without the tyre slipping. You may notice that mass is not part of the equation. Would you like to dispute that now?

If you still doubt me I can do the other two equations (acceleration and braking) for you. But this one was the most complicated so I thought I would explain it.

I am in no way saying that they will be faster or slower, just that they do not have any more or less grip.

Come at me.

[Moooools]

All riders experience the same amount of grip???? BOLLOCKS
Has nothing to do with many things listed so far comes down to what tyres they are using what compound that tyre is and what pressures they are running and also how well they bike is set up

Wake up man. I was saying that if you ignore other factors, a heavy rider does not get any more or less grip than a light rider.

[Shaun]

2 alternative Nick Coles, in all respects the same but one is 110kg and the other is 90kg. 2 green Kawasakis both exactly the same except one is set up for 110kg Nick Cole and the other is set up for 90kg Nick Cole.
Who is going to lap faster?


me in the peak of my riding and fitness hahaha 63 kg, who the fek was gunna keep up with that out of each corner on a race track

[gixerracer]

me in the peak of my riding and fitness hahaha 63 kg, who the fek was gunna keep up with that out of each corner on a race track

With the compression ratio you run you could have weighed 100kgs :facepalm: Dennis was only 50something kgs and even he still couldnt out gas you:innocent:

[slowpoke]

That's cute. But the second law of motion more closely states that the change is momentum is related to force x time.

Right now I am thinking that "Schrodingers cat" must be one of those ironic names...

If you had bothered to read all of it you may have understood. Or maybe not, perhaps there is no hope for you. I will however persevere.

Here is are the equations FOR THE CORNERING ASPECT:

F = ma
a(acceleration towards the centre of the corner) = v^2(velocity squared)/r(radius)

So if you combine the two... F(acrossways) = mv^2/r This is the force required by the tires to maintain circular motion.

The maximum corner speed is when this force is equal to the maximum force that the tires can exert without slipping. This is given by:

F(acrossways) = k(friction constant of the tyre)x F(downwards)

F(downwards) = m(mass) x g(gravity)

Sooo.... F(acrossways) = k x m x g

Now we make the two equations equal to each other.

k x m x g = mv^2/r You will notice that there is an m on each side, representing mass(of rider and bike). These can be cancelled off.

Sooo.... k x g = v^2/r

v = Squareroot(k x g x r)

The v above is the maximum speed a bike can travel around a corner without the tyre slipping. You may notice that mass is not part of the equation. Would you like to dispute that now?

If you still doubt me I can do the other two equations (acceleration and braking) for you. But this one was the most complicated so I thought I would explain it.

I am in no way saying that they will be faster or slower, just that they do not have any more or less grip.

Come at me.

Show me a 100kg 125GP champion. No? Why not?

[Matt Bleck]

2 alternative Nick Coles, in all respects the same but one is 110kg and the other is 90kg. 2 green Kawasakis both exactly the same except one is set up for 110kg Nick Cole and the other is set up for 90kg Nick Cole.
Who is going to lap faster?

Wouldn't the 90kg one would be classed as a "heavy" road racer? :shutup:

[Shaun]

With the compression ratio you run you could have weighed 100kgs :facepalm: Dennis was only 50something kgs and even he still couldnt out gas you:innocent:


you Protested you won and I got disqaulified eh, well done crasher. now go and tighten ya clip ons properlly. CBR cams checked officaually after manfield, GSXR cams and cases after Pukekohe, Boring dude, if it;s NOT prooven, it;s only rumour and Bull shit

[Moooools]

Show me a 100kg 125GP champion. No? Why not?

Facepalm. :facepalm::facepalm::facepalm:

Please read. I am not saying that a heavy rider can accelerate or brake as fast as a light rider, as there are limits on horsepower.

All I am saying is that a heavy rider and a light rider given infinite horsepower and braking power, would reach the limits of their tires at the same point.

I have said nothing about actual speed. Only about the limits of their tires which was brought up by the OP.

[Robert Taylor]

Wouldn't the 90kg one would be classed as a "heavy" road racer? :shutup:

But of course.

[SWERVE]

Heres a more simple equation
T= Talent.
T - $ = :second:
$ - T =:doctor:
T + $ = :first:

[Robert Taylor]

Facepalm. :facepalm::facepalm::facepalm:

Please read. I am not saying that a heavy rider can accelerate or brake as fast as a light rider, as there are limits on horsepower.

All I am saying is that a heavy rider and a light rider given infinite horsepower and braking power, would reach the limits of their tires at the same point.

I have said nothing about actual speed. Only about the limits of their tires which was brought up by the OP.

I hear what you are saying. Much of our work with road racing is managing rate of fore and aft weight transfer and how much pressure is placed on the tyres. A lighter rider will require in the first instance lighter springing. But also lighter valving. Its all about getting just the right amount of weight transfer to put enough pressure on the tyres to maximise mechanical grip between the tyre and the track. Of course myriad other factors also come into play, some of them contradictory
And then there are racing classes such as Formula Ford ( Praying Mantis's ) These cars dont have enough power to pull the skin off a rice pudding and often you deliberately take away some grip to stop ''scrubbing off '' too much speed.
Your third paragraph, while contestable does make some sense.

[Robert Taylor]

you Protested you won and I got disqaulified eh, well done crasher. now go and tighten ya clip ons properlly. CBR cams checked officaually after manfield, GSXR cams and cases after Pukekohe, Boring dude, if it;s NOT prooven, it;s only rumour and Bull shit

I think the whole clip on thing is worthy of a post in itself, there was exactly the same issue in the States and that took some time to unravel. Its only when we alerted the manufacturer of the problem that they owned up to it. BPF forks with thin wall upper tubes and sliding glide bushings that at ''full closed'' will work in the area of the handlebar clamps are a real issue. This doesnt always show itself in the pits but under load ''on track'' bind occurs.
Aftermarket clamps are poorly toleranced and will distort sliding surfaces while under racetrack load. I will put up a post about this as no-one should go through the grief Craig did with aftermarket clamps.

[Shaun]

I think the whole clip on thing is worthy of a post in itself, there was exactly the same issue in the States and that took some time to unravel. Its only when we alerted the manufacturer of the problem that they owned up to it. BPF forks with thin wall upper tubes and sliding glide bushings that at ''full closed'' will work in the area of the handlebar clamps are a real issue. This doesnt always show itself in the pits but under load ''on track'' bind occurs.
Aftermarket clamps are poorly toleranced and will distort sliding surfaces while under racetrack load. I will put up a post about this as no-one should go through the grief Craig did with aftermarket clamps.



Good on ya, people do need to be made aware of it, especially with the Internet shopping going on, some one may purchase a set as they may be cheap, but they are also crap and DANGEROUS

[SWERVE]

Have had a similar problem with custom made clip-ons for my 675.... made by a "so-called" race engineer.............. they are currently living in the scrap bin.
bet this problem is more common than you think.

[Shaun]

Have had a similar problem with custom made clip-ons for my 675.... made by a "so-called" race engineer.............. they are currently living in the scrap bin.
bet this problem is more common than you think.



STD IS BEST, ( Tourqued up properlly) they even Crash better normally

[schrodingers cat]

That's cute. But the second law of motion more closely states that the change is momentum is related to force x time.

I am in no way saying that they will be faster or slower, just that they do not have any more or less grip.

Come at me.

Absolutely correct.

But the question essentially was whether or not more weight (mass) should be an advantage.

Your calculations presume the same speed, corner radius and friction constant of the tyre.

To go faster, the question needs to be what is the friction potential of the tyre at any given state and how to realise that. (Actual friction circle performance vs theoretical)

As stated before, tyre temp and tyre compound are major contributors in relation to loading (non linear load/grip relationship) and influenced by rider position and suspension settings to load and control the contact patch.
Rider technique juggles the corner radii (because on the road or race track it is extremly rare to have a constant radius for more than 30m at the extremes of grip) to achieve maximum possible traction in the appropriate direction so as to maintain best lap time.

My point is that if there two riders of identical ability, riding the same bike on the same track under the same conditions the lighter rider would be faster.

At World Class level it is more difficult for a heavier rider to overcome his inherant disadvantage.

Fortunately, at lower levels there are so many variables, the negative impact of being heavier isn't as obvious.

The rider who get more things right wins.

Besides, it is cheaper to eat less pies than spend money on titanium and carbon fibre...

[Kickaha]

Besides, it is cheaper to eat less pies than spend money on titanium and carbon fibre...

Nowhere near as much wank factor though

[slowpoke]

Facepalm. :facepalm::facepalm::facepalm:

Please read. I am not saying that a heavy rider can accelerate or brake as fast as a light rider, as there are limits on horsepower.

All I am saying is that a heavy rider and a light rider given infinite horsepower and braking power, would reach the limits of their tires at the same point.

I have said nothing about actual speed. Only about the limits of their tires which was brought up by the OP.

Easy big fulla, take off the cranky pants and put on something a lil' more comfortable.

How are people are supposed to read " a heavy rider and a light rider given infinite horsepower and braking power, would reach the limits of their tires at the same point." out of you're post? And when I can find a bike with "infinite horsepower and braking power" I might actually come back and revisit your argument....

Until then I'll content myself with the fact that mass has to be accelerated and decelerated in a straight line as well as centripetally. So given a difference in mass there has to be a difference in force (Force =Mass x Acceleration).

We're also trying to exert this force to travel a set distance in the shortest amount of time, right? Which equals Work. Work = (Force x Distance)/Time? And what is the unit of Work? Horsepower. Therefore for 2 riders of different weight to travel the same distance in the same time the heavier rider must use more horsepower (work done by engine, brakes, tyres). But if we're talking equally talented riders on equal bikes performing the same work, the heavier rider must take longer.

This is very simplistic, but it's how it sits ok in my head.

[gixerracer]

:scooter::love:
you Protested you won and I got disqaulified eh, well done crasher. now go and tighten ya clip ons properlly. CBR cams checked officaually after manfield, GSXR cams and cases after Pukekohe, Boring dude, if it;s NOT prooven, it;s only rumour and Bull shit

Geez y so defensive Shaun I seem to have struck a nerve? Y would I bother protesting in NZ what would be the point we all no how that system works.
I Didnt say anything about cams but now you have bought them up it leaves me wondering. Have you forgotten the conversation we had about the front forks on your championship winning cbr 6?????????? Memory loss is a bitch sometimes ae:yes::facepalm::innocent::violin:

[Shaun]

:scooter::love:

Geez y so defensive Shaun I seem to have struck a nerve? Y would I bother protesting in NZ what would be the point we all no how that system works.
I Didnt say anything about cams but now you have bought them up it leaves me wondering. Have you forgotten the conversation we had about the front forks on your championship winning cbr 6?????????? Memory loss is a bitch sometimes ae:yes::facepalm::innocent::violin:


No Memory loss dude, I won U lost simple:yes:

[lostinflyz]

Absolutely correct.

But the question essentially was whether or not more weight (mass) should be an advantage.

Your calculations presume the same speed, corner radius and friction constant of the tyre.

To go faster, the question needs to be what is the friction potential of the tyre at any given state and how to realise that. (Actual friction circle performance vs theoretical)

As stated before, tyre temp and tyre compound are major contributors in relation to loading (non linear load/grip relationship) and influenced by rider position and suspension settings to load and control the contact patch.
Rider technique juggles the corner radii (because on the road or race track it is extremly rare to have a constant radius for more than 30m at the extremes of grip) to achieve maximum possible traction in the appropriate direction so as to maintain best lap time.

My point is that if there two riders of identical ability, riding the same bike on the same track under the same conditions the lighter rider would be faster.

At World Class level it is more difficult for a heavier rider to overcome his inherant disadvantage.



really..........

http://www.motomatters.com/analysis/2011/04/13/number_crunching_how_much_of_a_factor_is.html

The idea of identically talented riders and spec'd bikes on a track is useless as it is easily possible for their to be situations where either the heavier or lighter ride would launched from the bike due to being unable or unable to place load in a certain position to maintain the neccesary rate of acceleration/turning/deceleration. So in this hypothetical situation all you would have is one fast rider and one broken rider.

The whole argument surrounding rider weight to tyre grip is meaningless without considering the whole picture.

[gixerracer]

No Memory loss dude, I won U lost simple:yes:

Hahahahahahaha nice comeback:facepalm:

[crazy man]

I'm completely naive about racing, not having any knowledge about it at all.

I've been trying to learn more about tyres recently. The subject complexity greatly exceeds my abilities.

One thing I have learned though is that tyre traction is greatly related to "weight".

This got me thinking; a lot of effort goes into making motorbikes lighter for greater acceleration - but this must come at the cost of reduced traction.

If a 1000cc bike is being ridden so that it is constantly breaking traction on the track; then perhaps the rider would be better to actually make the bike heavier again, as more traction would surely result in greater acceleration. Otherwise it seems to me that you just have more power than you are able to use.that fat Sheriffs guy once won a race Robert Taylor told me

[schrodingers cat]

really..........

http://www.motomatters.com/analysis/2011/04/13/number_crunching_how_much_of_a_factor_is.html

The whole argument surrounding rider weight to tyre grip is meaningless without considering the whole picture.

Fantastic find. Read and noted.

I did think it was clear that I do consider the whole picture.

Ans I must say that a 72kg 'heavyweight' is scarely a fatty...

[Kickaha]

Ans I must say that a 72kg 'heavyweight' is scarely a fatty...

If it is then I am morbidly obese, not quite as heavy as that fat cunt Shirrifs though

[gixerracer]

that fat Sheriffs guy once won a race Robert Taylor told me

Dont ever beleive anything that cunt tells you

[gixerracer]

If it is then I am morbidly obese, not quite as heavy as that fat cunt Shirrifs though

Hahaha not as fast either

[Moooools]

Easy big fulla, take off the cranky pants and put on something a lil' more comfortable.

How are people are supposed to read " a heavy rider and a light rider given infinite horsepower and braking power, would reach the limits of their tires at the same point." out of you're post? And when I can find a bike with "infinite horsepower and braking power" I might actually come back and revisit your argument....

Until then I'll content myself with the fact that mass has to be accelerated and decelerated in a straight line as well as centripetally. So given a difference in mass there has to be a difference in force (Force =Mass x Acceleration).

We're also trying to exert this force to travel a set distance in the shortest amount of time, right? Which equals Work. Work = (Force x Distance)/Time? And what is the unit of Work? Horsepower. Therefore for 2 riders of different weight to travel the same distance in the same time the heavier rider must use more horsepower (work done by engine, brakes, tyres). But if we're talking equally talented riders on equal bikes performing the same work, the heavier rider must take longer.

This is very simplistic, but it's how it sits ok in my head.

I will have you know I am wearing my fat pants from the warehouse. And they are exceedingly comfortable.

The 'infinite power and and braking' part was just to clarify exactly what I meant. I implied that it was not taking into account these two factors but maybe that was a bit subtle. Saying that they are infinite just makes it abundantly clear what I mean.

The term you re looking for is not 'work' it is 'power'. Work refers to energy not power. The equation is right however, and your following statement is true. But that was not the point of my post. The post was simply talking about grip. Just grip. Only grip. Nothing but grip. Something other than grip? No nothing else.

Understood?

[Robert Taylor]

Dont ever beleive anything that cunt tells you

Aside from the fact Im a good c..t and you are going to win more races

[crazy man]

Dont ever beleive anything that cunt tells youl dont!!! he never gets your bike set up right! you are better of with a dead chinese to work on it lol

[Robert Taylor]

l dont!!! he never gets your bike set up right! you are better of with a dead chinese to work on it lol

And you are?

BTW 5 current NZ champions and a number of those who defected from that tyre changing guy and teller of ripping yarns might just disagree with your humorous statement

[CHOPPA]

Aside from the fact Im a good c..t and you are going to win more races

Thats just blown ya credibility RT! haha

[crazy man]

And you are?

BTW 5 current NZ champions and a number of those who defected from that tyre changing guy and teller of ripping yarns might just disagree with your humorous statementlooks like l will have to put you in the cooking pot for that

[Shaun]

looks like l will have to put you in the cooking pot for that


You look so much like Glen williams the ugly one:gob: your av that is

[codgyoleracer]

You look so much like Glen williams the ugly one:gob: your av that is

As i said to him before, "He's so ugly that even dogs close there eyes when they are dry humping his leg".

[Shaun]

As i said to him before, "He's so ugly that even dogs close there eyes when they are dry humping his leg".




Like ya style RED

[crazy man]

As i said to him before, "He's so ugly that even dogs close there eyes when they are dry humping his leg".please dont talk to your self lmao

[codgyoleracer]

please dont talk to your self lmao

I think you are confusing me with your best mate G.H

[crazy man]

I think you are confusing me with your best mate G.Hbugger l stuffed up sorry

[Dave-]

So I've skim read over this thread, I'm pretty sure I get what everyone is saying (or trying to say)

here's how I see it.

the taller, lighter rider has the cornering advantage, by modeling a motorcyclist as a mass rotating around a parallel axis (using parallel axis theorm) the rider who's mass is closest to the axis with the lowest weight will have the lower tangential force which means the corner can be completed at a greater angular velocity.

in a straight line here's how I see it.

we know there is a static force of friction, that is the absolute force that the tyre will not slip at, any more and it begins slipping and becomes the kinetic force of friction, the equation is F.s = u * N (where I'm missing a load of sub script and a greek letter).

we also know the tyre excerts a torque and a tangential force is found as T = I * w (where I'm missing another 2 greek letters) and the tangential force will be divided by the radius.

so we can find the force at which a tyre will slip given the radius and mass and angular acceleration of the tyre and the weight of bike (assuming it has no front wheel, divide by the mass distribution) and coefficient of friction of a given tyre by saying:

(I * w)/r = u * N and solve for whatever dependant variable you wish, input the rest.

and because a wheel is an odd shape you'll have to do some pretty strange maths to work out the moment of intertia (yay torsional oscilations!) but that's beside the point.

what you really need to do next is solve the equation for angular acceleration and find the limit as mass tends to infinity.

I'm pretty sure I'm right, I'll ask my lab tutor in about a weeks time.

[Kickaha]

we know there is a static force of friction, that is the absolute force that the tyre will not slip at, any more and it begins slipping and becomes the kinetic force of friction, the equation is F.s = u * N (where I'm missing a load of sub script and a greek letter).

we also know the tyre excerts a torque and a tangential force is found as T = I * w (where I'm missing another 2 greek letters) and the tangential force will be divided by the radius.

so we can find the force at which a tyre will slip given the radius and mass and angular acceleration of the tyre and the weight of bike (assuming it has no front wheel, divide by the mass distribution) and coefficient of friction of a given tyre by saying:

(I * w)/r = u * N and solve for whatever dependant variable you wish, input the rest.

and because a wheel is an odd shape you'll have to do some pretty strange maths to work out the moment of intertia (yay torsional oscilations!) but that's beside the point.

what you really need to do next is solve the equation for angular acceleration and find the limit as mass tends to infinity.



Quick everybody run and hide the University educated have arrived to baffle us with bullshit no one in the real world cares about

[SWERVE]

We all know that the only education you really learn at Uni are
Which pubs sell the cheapest beer:drinkup:
Which dealer sells the best drugs
And which girls (or boys !!!) sleep around.
All the basics to then go on and run the country............................:facepalm:

[crazy man]

:laugh:
We all know that the only education you really learn at Uni are
Which pubs sell the cheapest beer:drinkup:
Which dealer sells the best drugs
And which girls (or boys !!!) sleep around.
All the basics to then go on and run the country............................:facepalm:lmao your right there

[Dave-]

Quick everybody run and hide the University educated have arrived to baffle us with bullshit no one in the real world cares about

ah yes, the real world devoid of physics.

[Kickaha]

ah yes, the real world devoid of physics.

Your education can't have been very good if you think there's a world devoid of physics

I'd ask for my money back if I was you

[Dave-]

Your education can't have been very good if you think there's a world devoid of physics

I'd ask for my money back if I was you

I've got better things to do with my time than waste it here.

see ya!

[Shaun]

I've got better things to do with my time than waste it here.

see ya!


me to but IM drunk again and cannot drive

[schrodingers cat]

This page needs a sarcasm smiley
seriously

[schrodingers cat]

So I've skim read over this thread, I'm pretty sure I get what everyone is saying (or trying to say)

here's how I see it.

the taller, lighter rider has the cornering advantage, by modeling a motorcyclist as a mass rotating around a parallel axis (using parallel axis theorm) the rider who's mass is closest to the axis with the lowest weight will have the lower tangential force which means the corner can be completed at a greater angular velocity.

in a straight line here's how I see it.

we know there is a static force of friction, that is the absolute force that the tyre will not slip at, any more and it begins slipping and becomes the kinetic force of friction, the equation is F.s = u * N (where I'm missing a load of sub script and a greek letter).

we also know the tyre excerts a torque and a tangential force is found as T = I * w (where I'm missing another 2 greek letters) and the tangential force will be divided by the radius.

so we can find the force at which a tyre will slip given the radius and mass and angular acceleration of the tyre and the weight of bike (assuming it has no front wheel, divide by the mass distribution) and coefficient of friction of a given tyre by saying:

(I * w)/r = u * N and solve for whatever dependant variable you wish, input the rest.

and because a wheel is an odd shape you'll have to do some pretty strange maths to work out the moment of intertia (yay torsional oscilations!) but that's beside the point.

what you really need to do next is solve the equation for angular acceleration and find the limit as mass tends to infinity.

I'm pretty sure I'm right, I'll ask my lab tutor in about a weeks time.

Sounds pretty right - for a single instant and as you admit yourself, assuming a single wheel of a regular shape.

You've just opened the whole can of worms - two wheels, transiant states, changing track surface (friction potential)

You can see why peole say 'Just get on the thing and wring its neck'

Good post tho

[RobGassit]

He could win if he could find his bike. Somebody with a degree calculate these odds.242611

[SWERVE]

He could win if he could find his bike. Somebody with degree calculate these odds.242611

I would say the odds of finding anything in there are.......... slim(unlike her haha)
Imagine what went through his head before tackling that.:eek:.............. must have felt like Sir Ed when he first stood at the base of Everest and looked up.

Just a pic you happened to have on file Mr Gassit......:bleh:

[Kickaha]

Just a pic you happened to have on file Mr Gassit......:bleh:

From his family album

[RobGassit]

Is it wrong to like them big?:blip:

[RobGassit]

Actually I googled "Buell on top" and this was the first hit!

[Dave-]

So I've skim read over this thread, I'm pretty sure I get what everyone is saying (or trying to say)

here's how I see it.

the taller, lighter rider has the cornering advantage, by modeling a motorcyclist as a mass rotating around a parallel axis (using parallel axis theorm) the rider who's mass is closest to the axis with the lowest weight will have the lower tangential force which means the corner can be completed at a greater angular velocity.

in a straight line here's how I see it.

we know there is a static force of friction, that is the absolute force that the tyre will not slip at, any more and it begins slipping and becomes the kinetic force of friction, the equation is F.s = u * N (where I'm missing a load of sub script and a greek letter).

we also know the tyre excerts a torque and a tangential force is found as T = I * w (where I'm missing another 2 greek letters) and the tangential force will be divided by the radius.

so we can find the force at which a tyre will slip given the radius and mass and angular acceleration of the tyre and the weight of bike (assuming it has no front wheel, divide by the mass distribution) and coefficient of friction of a given tyre by saying:

(I * w)/r = u * N and solve for whatever dependant variable you wish, input the rest.

and because a wheel is an odd shape you'll have to do some pretty strange maths to work out the moment of intertia (yay torsional oscilations!) but that's beside the point.

what you really need to do next is solve the equation for angular acceleration and find the limit as mass tends to infinity.

I'm pretty sure I'm right, I'll ask my lab tutor in about a weeks time.

Sorry to Necro, but turns out I'm right.

The mass holding the bike down does provide an increase in grip allowing the bike to accelerate at a rate given the mass, however the acceleration of the bike is impeded by the same mass, therefore the weight of a rider has no effect on the bikes performance....but we all know this isn't entirely true and the explanation lies in the slipping of the tyre, which we assumed the wheel did not do.

I think most of the difference lies in tyre slippage, but also rubber compounds, aerodynamics, engine design (gear ratios, fuel rates, rpm) will be reasonable contributions also.

For now, my advice is experimental or "just ride the fuckin' thing"