MotoGP 2012

[Ray916MN]

^ HP though is calculated from torque in a linear equation (HP = Torque x RPM ÷ 5252), weight has nothing to do with it.  Power-to-weight ratio will remain consistent across riders irrespective of the torque (HP) increase. 

At this level, top speed has nothing to do with winning races.  As in F1, it is all about the chassis and managing tyre wear.

Yes, it is to some degree about chassis and managing tire wear, and within this an issue is how to get rideability, a key piece of which is drive out of turns. Torque has much to do with this, but you have to think of torque not in terms of peak power (ie. at maximum hp), but the torque curve below peak power. So lets say all MotoGP bikes have a 16000 rpm redline and produce 125 ft. lbs of torque at redline to make the math easy (200 hp). Let's say one produces 100 ft.lbs of torque at 14000 rpm and another produces 80 ft. lbs of torque, while peak power is the same below peak power is very different (140 vs 112 hp) at this lower rpm. The increased torque reduces the impact of weight on acceleration. Increased displacement allows more torque to be produced below the limits of peak rpms, making more horsepower available across the entire rpm range. This translates into improvements in rideability and reduction in the impact of weight on performance. All riders get access to the same increased power, but the heavier riders benefit more from it whenever the lighter riders are traction limited and the heavier riders are torque limited in acceleration. Remember gravity impacts all riders equally, but due to being heavier, a heavier rider should be able to generate more traction due to their greater weight. This is exactly the idea behind aerodynamic down force, generate more traction by generating more force (weight).

[Tim...]

It has everything to do with with chassis and tyre management.  Yes gravity aids in traction on the corners, but not on the straights - look to F1 and the DRS system.  If the lighter riders are to gain an advantage due to the 1000cc displacement, Pedrosa will run away with every race.  Do you seriously consider this viable?   

[Ray916MN]

It has everything to do with with chassis and tyre management.  Yes gravity aids in traction on the corners, but not on the straights - look to F1 and the DRS system.  If the lighter riders are to gain an advantage due to the 1000cc displacement, Pedrosa will run away with every race.  Do you seriously consider this viable?   

The point is heavier riders benefit more from increased displacement. The extra torque and power, helps them use the extra traction from being heavier to get better drive out of corners.

Put another way, acceleration is limited by power or by traction. When power is in abundance traction becomes the greater limiter. The more power, the more focus on traction gets you benefits.

[Tim...]

The point is heavier riders benefit more from increased displacement. The extra torque and power, helps them use the extra traction from being heavier to get better drive out of corners.

Put another way, acceleration is limited by power or by traction. When power is in abundance traction becomes the greater limiter. The more power, the more focus on traction gets you benefits.

Sorry Ray, I just do not get where you are coming from.  Isn't "dialing in the suspension", which is primarily subject to a  person's weight, all about maximizing traction regardless of the displacement of the bike. 

Now let's talk about traction control...

[Deplorable, thank you!]

How and why a bike can or does go faster is far more complex than what any single answer can provide....

The extra displacement will indeed help out the heavier riders more than the lighter riders. Why you ask.........

I won't answer, I will simply give you an example everyone can readily associate with...

Lets say Rider A has a 250 ninja
 he/she is out riding by themself the bike gets up and goes just fine and is more than capable of accelerating at a spirited pace. Now lets say this person puts a passenger on the bike....That same bike does not accelerate so crisply and it certainly doesn't accelerate at a spirited pace...The extra weight on that small amount of horsepower available is catastrophic to its ability to accelerate.

Now take Rider B on their Literbike
 You are riding solo...The bike will accelerate so hard it will pull your arms out of there sockets if you aren't ready for it (exaggeration)
 Now add a passenger, the bike will still accelerate so hard that it will damn near pull your arms out of your sockets (more exaggeration)

This more weight added to the underpowered bike (ie...800cc) is a catastrophic affect on acceleration, whereas that same added weight to the higher powered bike has a far less devastating affect on its acceleration


These examples are purely for dramatic affect, clearly the power difference between a 250cc street bike vs a 1000cc street bike is far greater than the difference of a 800cc gp bike vs a 1000cc gp bike.

Of course suspensions, tires, tire pressures, rider, bike geometry and a zillion (exaggeration) other factors come into play....But wasn't the discussion just about the power to weight ratio difference???

[Ray916MN]

The point is heavier riders benefit more from increased displacement. The extra torque and power, helps them use the extra traction from being heavier to get better drive out of corners.

Put another way, acceleration is limited by power or by traction. When power is in abundance traction becomes the greater limiter. The more power, the more focus on traction gets you benefits.

Sorry Ray, I just do not get where you are coming from.  Isn't "dialing in the suspension", which is primarily subject to a  person's weight, all about maximizing traction regardless of the displacement of the bike. 

Now let's talk about traction control...

It is maximizing the traction for a given weight but it can not change the fundamental amount of traction available.

Oversimplifying traction (using the simplest formula for friction/traction)

Frictional force can be expressed as

     Ff = ? N       
     where
     Ff = frictional force (N, lb)
     ? = static (?s) or kinetic (?k) frictional coefficient
     N = normal force (N, lb)

Normal force is calculated using F=MA  where M=the weight of the rider and bike and A = gravitational acceleration (9.8m/s^2). Since gravitational acceleration is a constant, F goes up as rider weight goes up and frictional force (traction) goes up as weight goes up. Assuming riders are on the same tires and riding the same pavement, then the  ? = static (?s) or kinetic (?k) frictional coefficient will be the same for both riders.   This means a 15% heavier rider has 15% more traction available for a given situation than a lighter rider, assuming their bikes weigh the same. The is the fundamental optimal traction. It assumes equally well set up suspension on both bikes too.

So why doesn't the heavier riders with 20% more traction go faster than the lighter rider? Because F=MA. Given equal force available from engines the lighter riders will accelerate faster F/M=A. Using the example of a 15% heavier rider the lighter rider will accelerate 13% slower (1-1/1.15). But their is hope for the heavier rider. at the point where the force of acceleration can overcome the available traction, acceleration is essentially stops or tails off to nearly 0. At this point, if there is more force available, the heavier rider can make use of the additional available force to continue to accelerate, whereas the lighter rider has reached the limits of acceleration due to loss of traction and can not make use of the additional force.

Looking at from a different perspective may help. Let's assume that you had an engine which produced an infinite amount of horsepower at any RPM. If you had such an engine you would be capable of running a motorcycle to the limits of traction at an instant and in any situation. In this situation, a heaver riders would be at the least disadvantage to a lighter rider.  With infinite force available, their weight would no longer be a handicap (the acceleration penalty from weight can be overcome by having more force available , and they would be able to take advantage of 15% greater traction at any and every instant. The bigger the displacement, the closer and engine can be made to having an infinite amount of horsepower at any RPM.

[Jared]

STOP DORKING UP MY GP THREAD!!!!!!!!!!!!!!!!!


































joking...kind of.

[Tim...]

^ so what is your viewpoint? 

Tomorrow's race should be interesting, Lorenzo on pole with Stoner putting pressure on him in the first corner - let's see how Lorenzo handles it.  IMHO the battle for first is between these two.  Spies can get the scraps but he going to have to battle Cruthlow on the non-factory Tech Trios bike - let's see how Spies handles that pressure.

Damn, I love racing season

[Jared]

Bombshell: Stoner will retire are the end of this season.

http://www.crash.net/motogp/news/179806/1/casey_stoner_to_retire_from_motogp.html

[Chris]

Bombshell: Stoner will retire are the end of this season.

http://www.crash.net/motogp/news/179806/1/casey_stoner_to_retire_from_motogp.html

I sure hope so, I don't know what it is about him but I can't stand him.

[Tim...]

Think he got tired of doing interviews wearing a hat that is much too big for him.

[Jared]

Think he got tired of doing interviews wearing a hat that is much too big for him.

I don't think Repsol or Bridgestone have a child size line...

[Jared]

Rookie rule is gone.  Rumor is that Marquez is already signed as Casey's replacement.

http://www.crash.net/motogp/news/181003/1/ezpeleta_explains_motogp_rookie_rule_change_of_heart.html

Rossi as owner/operator?

http://www.superbikeplanet.com/2012/Jun/120621c17.htm

[Chris]

do you really think that Filippo Preziosi is the reason that the Duc's have been doing so bad for the last 4-5 years? He has been the technical director since 1999.

[Jared]

Rossi's tire as he pulled off this weekend...