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

[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

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

[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

[Str8 Jacket]

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

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