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Old 08-13-2004, 09:42 AM   #21
red-silver
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Default Re: R1 vs 911

Where to start? First of all at the F1 level cars go way, way, faster than the GP bikes, as much as 20 seconds a lap on some circuits. Consider that the acceleration, and top speeds of these vehicles are about the same, in fact this year the staightaway speeds at some tracks have actually been higher on the bikes. That means the cars are way better on the brakes and carry some frighteningly high corner speeds. Because the bike has no aerodynamics working to increase download, the riders are dealing with much greater speed differentials in terms of acceleration/deceleration, I believe their job is much harder.

Secondly - the car stays essentially in a flat plane, the dynamics of the chassis load remain linear regardless of the speed. When the bike is at full lean the centrifugal forces is actually helping it more than a car, (if that car had no downforce assistance). Here comes the problem, at full lean, gravity is also acting vertically on the chassis, not inline with the direction of the centrifugal force, or the direction of the suspension (hence what happens with surface irregularity at full lean, this also includes the problem of torsional load, the chassis winding up and unwinding like a spring) Ever watch the continual head shake of the GP bikes,both under braking and acceleration? You can actually watch these guys exit a high speed corner, and watch the bike slide, shake its head and aviate the front end all at the same time!!!. This is why the idea of controlled frame flex is so critical in racing motorcycle design.

Third - trail is shortend and stability decreased on the bike exactly when stability is needed most, under heavy braking (hence everyone trying to figure out how to make the front fork obsolete & still do a good job of steering and suspending the motorcyle).

Fourth - there has to be some slip angle in the front tire for the bike to turn at all! Of all these engineering problems the aerodynamic issue is the biggest, if that can be figured out and applied to function in the multiple plane environment of the motorcyle, the speeds would at least be dramatically closer! It's all about traction and stability!

You gotta strong muscles, big huevos, quick reflexes and a sensitive ass to ride at the GP level!
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Old 08-13-2004, 10:08 AM   #23
Andonyx
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Default Re: Stick to insurance pal

Woah woah....



I'm not sure i'm reading Kpaul correctly, but I want to go on record as saying that my post is a guess at what may be the physics of the situation, because the topic post asked about the physics.



As far as the practical realities of riding a bike, and the engineering of race bike design, I make no claims whatsoever as I'm a cruiser guy and I know exactly jack about riding and racing at high speed.



So if I read the post the way I think I did, I'm not sure why the two posts must be at odds. But except for a couple minor points I don't see why my post and the above poster's view must be at odds. It seems mine was about some science issues, and the other was about the nitty gritty of the realities of sportbike riding.



Or perhaps I'm an ass and I'm reading this all wrong.
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Old 08-13-2004, 10:24 AM   #24
red-silver
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Default Re: Stick to insurance pal

Thank you ~ You spoke of the physics involved, I didn't see the contradiction either. It still comes down to traction and stability. Racecars with download can turn in quicker, brake later, and carry more g-load in the turn. I think you probably described quite accurately the issues.
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Old 08-13-2004, 10:25 AM   #25
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Default Lap Times at Daytona

To give you guys an idea of the difference in speed, Eric Bostrom had a pole time of 1:46.835 at Daytona this year. In happy hour this year at the Rolex 24 at Daytona, Tony Stewart ran a 1:49.422. To put it in another perspective, Marco Andretti ran a fastest lap of 2:11:542 at Daytona in a Skip Barber car (open wheel, wings, 150 HP, 1250 lbs fully fueled). Crappy (i.e. guys that are still way better than us) were running near 2:00.00 lap times at the Daytona 200 on superbike GSX-R1000s. And in the last perspective, the best SCCA raced prepared Mazda Miata (SSB class) at Daytona ran a 2:29.004. That is a huge difference to even the "****ty" superbike riders. Regardless of what is "faster" both cars and motorcycles are fun when driving at full speed. And believe me, a stock motorcycle goes through corners WAY faster than a stock car. There is one corner near where I live that my car (Camaro SS ~ .86 Gs on a skid pad) right before it starts to break away can manage maybe 102 mph. My bike, which I am not fully maxed out on, goes through the same corner over 130 mph. Mind you the bikes speedometer is off a good bit, but still. And this is a good comparison because I race cars and I know how to drive. Just thought I'd shoot my opinion.
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Old 08-13-2004, 10:40 AM   #27
Mooner
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Default Re: Stick to insurance pal

Ohhh, nevermind.....
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Old 08-13-2004, 10:53 AM   #29
Grappelli
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Default Re: R1 vs 911

One of the British bike press did a comparo where they put an R6 against a Subaru Imprezza Turbo (The non restricted European version) On the track, they were similar, with the R6 bing slightly faster.. However, on the road, with imperfect surfaces and no run off zones, the subaru was beating the R6, especially since it became hairy trying to ride at 10/10ths on the road on an R6. The main difference was the greater corner speed of the car.



Not my data, but thought I'd throw it into the pot.
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Old 08-13-2004, 11:08 AM   #30
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Default Re: R1 vs 911

The June 2004, British Supersport Qualifying Thruxton Round had Karl Harris qualifying his CBR 600RR on pole at 1:17.614 (flying lap). The 911 in the video did a standing start lap in a quoted 1:35.33. It is pretty clear that it wouldn't take 17 seconds for the bike to get from the start line to the first corner, so I think this test was BS. Mackenzie is a pretty damned fast rider, by the way...
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