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Discussion Starter #1
I'm developing a theory about what's really going on with the new 800s in relation to speed and rider weight.

So the question is this:

Does the weight of the rider really make a difference?

Simple empirical evidence might indicate that it does (Stoner, Elias), but there are other factors which might indicate that a lightweight rider is actually a hindrance in certain situations that might not be intuitive. There is information from the car racing world that might corroborate this.

(But I really would need better stats than are available to prove this.)

So, race fans and closet analysts, let me know what you think.
 

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from a purely physics standpoint, i'd have to say yes - lower momentum, less lateral loading on the tire, so on.

however, it seems to me that the rider's brain is more significant. somehow,
Rossi and Edwards can get around the track faster than almost all the other guys even though they both weigh a lot more than some of the smaller riders (Pedrobot, Stoner, Elias)

but there are several rider managers at the motogp level who are taking the horse jockey approach. only riders 5'2" or less need apply...

alex
 

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The thread title says are they (lightweight riders) better? I don't think they are better but they must have an advantage. Every sports bike manufacturer tries to get a few Kgs shaved off the latest offerings from Yamahondasuzi so it must help. I presume you mean that powerful GP bikes need a rider with some significant body mass to muscle them around Andy? I don't think that is the case these days although it might have been so 20 or 30 years ago. Just looking at little Loris Capirossi sliding the big desmodesici around last year is testament to that
 

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Discussion Starter #4
Look at qualifying as well, and don't forget Hopkins.

There seems to be 2 groupings of "fast" riders, using race results AND qualifying as determining factors:

At or below 59kg
At or above 67kg

With maybe Capirossi and Melandri breaking that rule.

I may be all wet, though. It may not be as significant as it seems (one of the problems with using statistics).
 

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Won't a heavier rider mean the bike has an overall higher center of gravity? So, flicking from side to side may be a bit easier. The down side is the extra weight puts more load on the tires and slows it down on the straights? I'm just guessing here.
 

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Discussion Starter #6
john said:
The thread title says are they (lightweight riders) better? I don't think they are better but they must have an advantage. Every sports bike manufacturer tries to get a few Kgs shaved off the latest offerings from Yamahondasuzi so it must help. I presume you mean that powerful GP bikes need a rider with some significant body mass to muscle them around Andy? I don't think that is the case these days although it might have been so 20 or 30 years ago. Just looking at little Loris Capirossi sliding the big desmodesici around last year is testament to that
There are obviously many factors, including strength. Reducing weight on the bike is probably always a good thing. But specifically, I'm talking about rider weight and what it has to do with results.

The lightest riders are not necessarily qualifying very well, although there are exceptions to that. A good package is a good package, which is what the Ducati is. But I might argue that a heavy rider might be able to go just as fast as Stoner on the Ducati. What Bayliss did last year might help prove that.
 

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acruhl said:
I'm developing a theory about what's really going on with the new 800s in relation to speed and rider weight.
.......but there are other factors which might indicate that a lightweight rider is actually a hindrance in certain situations that might not be intuitive. There is information from the car racing world that might corroborate this.
.......
I think your theory will be impossible to prove because physics doesn't agree and I'd like to see ANY information that a lighter rider is a hinderance in any auto racing. Most racing series, including Nascar and Formula 1 but excluding IRL, include the DRIVER's weight when determining minimum total weight requirement to equalize the lightweight driver's advantage.

The truth is fat and weight just doesn't make the cut on the race circuit. Last I checked Nicky Hayden at 150 lbs is one of the FAT men on the GP circuit and the fattest is a beast at 159 lbs, Pedrosa is a fly at 108 ls. Rossi at 130lbs is about the norm. There was not one MotoGP rider over 160 :cry: !

Last year weights:
1. Loris Capirossi (Ducati) ... 59 kg (130 lbs )
2. Daniel Pedrosa (Honda) ... 49 kg (108 lbs)
3. Nicky Hayden (Honda) ... 68 kg (150 lbs) --> 42 lbs more than Pedrosa!!!
4. Toni Elias (Honda) ... 55 kg (121 lbs)
5. Marco Melandri (Honda) ... 61 kg (135 lbs)
6. Casey Stoner (Honda) ... 58 kg (128 lbs)
7. Shinya Nakano (Kawasaki) ... 58 kg (128lbs)
8. Kenny Roberts (Team KR) ... 67 kg (148 lbs)
9. John Hopkins (Suzuki) ... 72 kg (159 lbs) --> The heaviest man in the GP circuit! 51 lbs more than Pedro
10. Makoto Tamada (Honda) ... 60 kg (132 lbs)
11. Colin Edwards (Yamaha) ... 66 kg (146 lbs)
12. Chris Vermeulen (Suzuki) ... 68 kg (150 lbs)
13. Carlos Checa (Yamaha) ... 69 kg (152 lbs)
14. Valentino Rossi (Yamaha) ... 59 kg (130 lbs)
15. Alex Hofmann (Ducati) ... 68 kg (150 lbs)

All that said - At club racer level, no one drawback is going to determine the outcome. Most riders are too far away from the maximum potential of the machine to be unable to compensate one deficiency with excelling in another area. :D

Tom
 

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Discussion Starter #8
TPadden said:
I think your theory will be impossible to prove because physics doesn't agree and I'd like to see ANY information that a lighter rider is a hinderance in any auto racing.
Ahh, but I didn't say a lighter driver was a hindrance in auto racing. I only said that I might have data from auto racing to corroborate that a heavier rider on a bike might have certain advantages :)

100% agree. In club racing, the most skilled rider wins every time. Machinery isn't that important. One of our guys, Mike Shreve, was pestering Mark Ledesma on his AMA superbike out at Firebird a few weeks ago. Mike was riding his supersport R6. Mark is no slouch, but it goes to show that almost anything is possible given the right conditions and riders.
 

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Discussion Starter #9
Ok, here's an obtuse hint related to my comment about car racing:

Some series regulate total race weight. To equalize weights in race cars, I believe I have read (still trying to find it) that teams may add ballast to the cars either in a pre-determined place (determined by the sanctioning body), or the center of the car, can't remember which.

Why would there be a stipulation for the location of the weight? (Therein may lie the answer.)
 

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acruhl said:
Look at qualifying as well, and don't forget Hopkins.......
There's stats and then there's stats! :)

There is some question about the accuracy of those "official MotoGP" figures on size for Hopkins. He's listed as 154 lbs there, but the Laguna program last year had him at 140 (and he looks pretty small to me). :jsm:

..... all that aside seems the "Mericans" are the "supersized" ones :smoking: !

Either way - it surely isn't all about weight .............. but that doesn't mean weight doesn't count or that light is a disadvantage.

Tom
 

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acruhl said:
Ok, here's an obtuse hint related to my comment about car racing:

Some series regulate total race weight. To equalize weights in race cars, I believe I have read (still trying to find it) that teams may add ballast to the cars either in a pre-determined place (determined by the sanctioning body), or the center of the car, can't remember which.

Why would there be a stipulation for the location of the weight? (Therein may lie the answer.)
Yes - where weight is placed does matter - but I don't know of any series that "equalize weights in cars". Most merely have minimum and maximum ranges and weight is added to penalize light cars to meet the minimum requirements.

Equal driver/ rider skills and equal equipment (everything else being equal) physics says the lighter driver/ rider will win every time.

Tom
 

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Discussion Starter #12
Yep, I should have said penalize, not equalize. But the series will specify where the weight can be put. Implying that weight placement may have it's advantages.

I also read an article about Angelle Seeling (now Angelle Sampey) and the advantages she had being a lightweight person. They could move certain parts of the bike to redistribute weight and things like this. I don't remeber the details.

Anyway, I think I'm seeing some of the heavier riders (who, coincedentally, are also usually taller), repositioning their weight in ways that the shorter guys can't do. With the rider aids in place, I think the heavier riders can shift their weight to benefit traction or whatever they are trying to accomplish.

This must be part of the explanation why the lighter weight guys don't just run away and hide? I don't know, but I'm watching for it...
 

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Strength, endurance and muscle mass certainly play a role as well. Tough to quantify but it's certainly possible that too little muscle (no guess as to what amount that is) isn't going to help. I can't imagine the 4th grader across the street has enough oats to control a GP bike but it would certainly go like hell if he figured out how to shift or managed to hang on.

Weight might be critical on a drag bike but strength isn't so important on a bike that only races for a few seconds and never turns, brakes from 210 mph for a 40mph corner, flicks through a set of esses, etc., etc., etc...

I think less weight is good once you get down to a certain point but less weight (or the other things that go along with it like insufficient size and strength) may cause problems.
 

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This is a very interesting thread and this is my take on the subject.

Assuming a base line of sufficient skill and equivalence of machine. What are the parameters that determine a race result or put another way the fastest time from A to B. Very simplistically these are

1. Acceleration
2. Deceleration (Braking)
3. Straight line speed
4. Corner grip
5. Rider Endurance

1. Acceleration is governed entirely by the power to weight ratio; Weight disadvantage 9 points
2. Is governed the physics of slowing a mass, here ground pressure is an important factor and the riders weight and his ability to reposition himself in the optimum position can be regarded as important; Weight advantage 4 points
3. Aerodynamics play a significant part here a large rider obviously can create more wind resistance than a small one.; Weight=size Disadvantage 4 points
4. Corner grip again is governed by ground pressure the more weight on a wheel the more it should resist spinning or sliding thus maintaining a higher or lower corner speed; Weight advantage 4 points
5. Rider endurance or the strength of a rider will play a major part in a race assuming a certain length. The ability to throw a machine at a bend or pick it up is a factor of rider strength and the duration and is determined by his fitness; Weight muscle mass Advantage 4 points

Disadvantage 13 Advantage 12 or very close

This is a very simple way of looking at it and of course there are overlaps. On balance I have found in the larger classes too much weight less of a handicap, the smaller the class the greater the handicap. What of course makes the major difference is the riders skill coupled with the machines performance.
 

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Discussion Starter #15 (Edited)
Thanks for that post. That's quantifying what I'm seeing, I think. Somewhere in that there is an equalizing factor between heavy and light riders where the pure physics doesn't tell the tale. And I think you've mostly nailed it.

There's a few things that I think I'm seeing and I'll just spit it out and see what people think:

Under braking, the heavier riders can stick right with the lighter riders, or even outbrake the lighter riders. I believe this might be due to weight distribution. The heavier rider can use more brake before the back wheel comes up.

Under acceleration, the heavier rider can get more weight on the back wheel, giving the traction control electronics more ability to put more power down because there is more traction available. (Think of a 100 pound person trying to push a 200 pound box. His shoes are going to slip. Put 100 pounds in his backpack, and he has a better chance of getting traction, given an abundance of power to keep pushing.) Somehow wheelies are prevented. I guess electronics are doing that too? This is all a function of traction, not physics, because obviously there is going to be a curve where the heavier the rider is, the less ability the bike has to overcome the simple physics problem of f=ma. But anyway, the rider getting better traction on corner exit may have a higher exit speed, which translates into a higher speed all the way to the next braking area.

Watch Rossi stick with or beat Stoner off of corner exits. This shouldn't be happening. Stoner comes around on pure horsepower eventually, but that's not Rossi's fault :)

One rule of physics that a heavier rider can't seem to break is corner speed. This is borne out by my own experience. I'm about 6'0", 200 pounds (on a good day). When I raced in the 600 class with other guys on very similar bikes, and the same tires, I simply couldn't keep up mid corner. I was pushing or sliding the rear, while they just railed through the corner. My only hope was to outbrake them at the next corner! So I learned how to use the brakes :)

Thanks Barry. That's putting what I was thinking into very simple to understand terms. I wasn't thinking of it that way.
 
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