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Discussion Starter #1
I do not condone street racing, but wanted to ask if anyone has ever come across a motorcycle ridden well enough to stick with you during spirited Cayman driving?

While it was in 1998 BMW M3 sedan, I did have this happen to me once. Three sport bikes came up behind me, right when I got to a favorite section of a road I frequent. I waved them past, but they did not want to pass. I hit the gas, as usual for this section of road, and two dropped back immediately (Honda and Ducati), but the third guy was no joke. Glancing in my rear view mirror, his Yamaha R1 was over hard on its side, the guys knees on the ground. Even under hard braking, he was still there. He could have killed me on acceleration, but elected to stay behind.

Got to the end of the road, and he slowly passed me, and gave me a big thumbs up. Was fun, and nice to see the bike ridden that well. I am not sure he (or anything) could stick with a well driven Cayman.

Phil
 

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I sold my motorcycle(Sportbike) and replaced it with A Boxster as it was closer to the thrill. It is an interesting performance question but the answer is not so simple.

1. Riding a bike at 90% requires more skill particularly in the curves.
2. Recovery from a mistake at the limit is difficult.
3. Straight line performance on a (Sport)bike is incredible(3lbs/hp).
4. Sweeping curves are fast and probably faster than Cayman.
5. Sportbikes are closer to their GP cousins than are sportscars.

However, bikes do not transition well in twisty courses and S curves. In a reversal, the bike has to rotate on a roll axis which takes driver effort and time. A sportscar changes direction with the flick of the wheel. A bike would probably get killed on an autocross course.

This of course applying to stock vehicles.
 

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Jryder said it well.

On a road course a well ridden sport bike would likely beat a well driven cayman. BUT, it is a lot harder to get the most of a bikes performance than a cars and the hazards are greater. I haven't ridden on the track in a while and I've moved to a sport tourer + my Cayman S.

On a tight tight twisty road a super moto might be what catches you buy surprise, it'll look like a dirt bike with road tires and they are quick, nimble, and awesome on the brakes but not much for top speed.
 

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I had an encounter with a big Yamaha the other day. He let me take off early, by 100mph he was overtaking me slowly. I ran out of room and decided we were crazy going that fast.
The guy enjoyed seeing a Porsche running hard.

Moto GP bikes run Silverstone in around 2 minutes where F1 cars do a lap in 1.5 minutes. 30 seconds is huge. Maybe a touring car lap time would be a better indicator of the car vs. bike argument.
Donor Cycles have to run lines that are like a ribbon. They get a little drift but nothing like a car. 2 wheels are not quite as forgiving. Sliding under someone in a car with an early apex is cool in a car,,, on a bike you are on a rail.
Bikes are so fast and nimble but a car has so much more control. Two equally matched machines having a close race??? I think the car would win.
What are lap times of bikes at Laguna Seca?
 

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I have had 16 motorcycles and raced when I was dumb and young. A couple of my pals went on to do it semi-pro and raced against national numbers. When got off the last one around age 40 promised the wifey would not do it again. All that said a good rider on a decent sport bike will kill even a GT3 divern very well. Our cars are just to be toyed with. Google up some lap times at tracks you are familiar with. At the limit or near a well prepred car is more in a normal persons ability, to ride a bike at the limit requires an exception athlete with a special skill set and balls the size of basketballs. I was more a motocross guy, the road racers were special breed.
 

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I had an encounter with a big Yamaha the other day. He let me take off early, by 100mph he was overtaking me slowly. I ran out of room and decided we were crazy going that fast.
The guy enjoyed seeing a Porsche running hard.

Two equally matched machines having a close race???
It pains me to admit how poor most people are at operating their motorcycles. What kind of "big yamaha" was it? It's too easy to go into a showroom and buy an insanely fast litter bike, so much so that most people own them without knowing how to really use them.

One of the hardest things to decided is what determines "equally matched."
A new Yamaha R1 has about 180 HP and weighs about 450 lbs. and costs around 13 grand new. I think it was the 2004 R1 that hit 104 mph in 1st gear.

So that's roughly 2.5 to 1 lb/hp ratio
Does that mean we need a 750 lb/300 hp car to compete against it?
What about 2 tires vs 4?

Surprisingly to most people, bikes actually have poor aerodynamics.

Is price a factor?

Yes, an F1 car is AWESOME and will outrun a moto gp bike around a track. They have more traction, downforce, and a stupid low center of gravity. Do they have active aerodynamics?

My BMW sport tourer will beat any N/A cayman S/R to 100 mph and I'm pretty sure I'll take the most stage 1 turbo/supercharged cars up to 100 (I know I will to 60 mph). That just comes down to power to weight ratio, it's still a 160 HP bike. Over 100 aerodynamics come into play and things will start to even out. In the turns my bike becomes a big heavy lug and needs some work to hustle and I wouldn't dream of chasing a well driven Cayman. In all fairness I have humbled a few crotch rockets even with the 3 piece luggage on my bike; track time is valuable on a bike or in a car.

The fact is, bikes and cars are apples and oranges. While it's fun to compare them and debate which is faster, it is almost impossible. For my money, there is no greater thrill than a used 600cc track bike. For under 4 grand you can get a dedicated track bike that will out perform 90% of the people riding it. That's why I got into motorcycles, I couldn't afford the cars I wanted.

If you see me around San Diego and the opportunity is right, I'll play.
 

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I do not condone street racing, but wanted to ask if anyone has ever come across a motorcycle ridden well enough to stick with you during spirited Cayman driving?
I think you phrased that incorrectly. You should be asking whether or not anyone has ever seen a car that can stick with your average liter bike. The 458 can come close:

Ferrari 458 Italia vs Ducati 1198S - Forza Italia! - YouTube

Yes, it does take skill to drive a bike well, but before you dismiss bikes, go out to your local track and check out the dozens, DOZENS of guys who can get within a second or two of the lap record.
 

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At the limit or near a well prepred car is more in a normal persons ability, to ride a bike at the limit requires an exception athlete with a special skill set and balls the size of basketballs. I was more a motocross guy, the road racers were special breed.
Yeah, I'm still not sure if it is more skill or more balls. Turns out I had neither. I remember one time I thought I was going pretty fast on the track when some 60-year-old on a touring bike passed me like I was standing still. I now drive a CS :D
 

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Discussion Starter #11
I am hardly dismissing bikes and know very well what it takes to ride one well. I roadraced motorcycles at Infineon for a few years. - Phil

Yes, it does take skill to drive a bike well, but before you dismiss bikes, go out to your local track and check out the dozens, DOZENS of guys who can get within a second or two of the lap record.
 

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Discussion Starter #12
Getting back to our cars (Cayman) and street bikes, I see lap times around 2:07 at Thunderhill (CA) for Cayman S models. Magazine editors riding stock 1 liter sport bikes are getting lap times of 1:57 or so. That is a very big difference, but know that a good part of it, if not all of it, is coming from straightline speed of the bikes. The bikes were hitting over 155 mph on Thunderhill.

Having chased some cars on sport motorcycles, the hardest area to keep up is tight twisty stuff. The more it opens up, the better. And without question, you need very high skills to ride well at speed, far more than the nearly unflappable Cayman at the same speeds. Where I was most comfortable keeping up with sports cars was fast sweepers. I will say that when ridden well, the satisfaction one feels is very gratifying. But there were days I could not ride at all, feeling like a complete klutz.

Phil
 

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I was riding my Suzuki V-Strom 1000 from San Juan Capistrano to Palm Springs on Highway 74 one beautiful morning. This is not a particularly fast bike as bikes go, electronically limited to 130 mph and 11.30 in the 1/4 mile, but a beautiful sounding 90 degree V-twin with a fat power band, 90 horsepower and weighing about 500 pounds. Leaving Hemet, heading east, I fell in behind a CL63 and a Ferrari driving together.

Early morning, noone else on the road. The section of Hwy 74 from Hemet to Palm Springs is simply awesome and these guys decided to play. I don't think they knew I was there at first, but as they opened up, I decided to stay with them. The Ferarri was in front, the CL second and me in the back. I planted myself in the CL's mirror and just stayed there. The road starts out from Hemet as about ten miles of pretty tight climbing curves and then opens up into big long high-speed sweepers in a high mountain valley.

We were running between 110 and 125mph and I was just rolling on and off the throttle and leaning through the curves staying in that Mercedes' mirror.

The last ten miles is a steep descent into the desert through some tight turns.

Wow, what fun. I had a huge grin planted the entire time. I would normally ride it at a "spirited" pace, but these guys caused me to push it a bit harder than I would have alone.
 

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Great thread. I was thinking about this as I barely kept up with a very nice looking Ducati a few weeks ago. Clearly he could have dropped me but I had great fun keeping up on a road that he knew and I didn't. Was gambling that he would know where the local law enforcement was. Never would have gone so fast on my own.

Interestingly my Cayman S has roughly the same stats as the 550cc bike I had 30 years ago in terms of 0-6 and 1/4 mile. Obviously the CS has a much higher top speed and I think likely accelerates much faster once you get over maybe 60mph. ...and I can't fall off at my advanced age....
 

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Yes, interesting thread. The physics is really critical here--and both helps and hurts the motorcycle relative to the car. High power to weight ratio means quick acceleration and high top speed, poor aerodynamics means scary high speed, two small contact patches and two brake discs makes for poor cornering and braking compared to a car with 4 large brakes and tires. Twistees really highlight the traction/braking difference in favor of the car.
When they "race" a car against a motorcycle on a race track, they are close, but the cars always "win." Official lap records at the Nurburgring have the fastest production bike doing 7'46" (Suzuki GSXR 1000 in 2008) and cars (although is a Viper ACR really a production car) doing it in 7'12". Walter Rohrl drive a Cayman S around in 8'04".
So, it's very likely that if you're driving in your CS and you take on a motorcycle, you'll come close or lose, but I hope it doesn't get to that point!
 

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Modern bikes do not have traction issues under braking or accelerating. It's not about the rubber. It's about the center of gravity being so high. They would be even faster if you could keep the nose down under acceleration and keep the tail down under braking, i.e. wheelies and stoppies prevent them from reaching maximum acceleration rates in straight lines.

The rubber is also not the issue when cornering. Bikes can also hit 1.5g or higher in turns, and they usually come with even better rubber than cars. However, when the bike leans over, the suspension travel is now in the wrong direction, making those tiny bumps upset the whole chassis. Also, as someone mentioned, to make a turn, the bike has to roll it's high center of gravity over the roll center, the axis that passes through the contact patches.
 

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OK, so if it's not traction and braking, then can you take a moment to supply the Cliff notes (or point me to equivalent on the 'net) explaining why the superior power to weight of the motorcycle doesn't translate into faster times on race tracks?
Thanks,
 

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First of all, we were comparing street bikes to street cars. In that case, the bike's physics DO translate into faster lap times on most tracks. Of course modified cars and some homologated cars may be faster than street bikes. But at Willow Springs, on the same day, in the same conditions, a GT2 champ in a 458 got beat soundly by a professional rider on an 1198S (which btw was not even the fastest street Duc available). Now I'm sure we can find tracks that favor the bike more or the car more or we can even find different bikes and cars to get slightly different results. The point is that a street bike is about as fast as the fastest exotics at 1/10 the price -- even in the twisties and even when the car is driven by a professional driver.

However, these are the things that I think are the biggest shortcomings for the bike:

1. Center of gravity is too high to utilize 100% of available traction.
2. Transitioning into/out of a turn takes more time due to #1.
3. Suspension geometry reduces reliable traction in a turn.

Keep in mind that if you the contact patch flat on the ground, the available acceleration in a turn is almost completely determined by the tire compound (not by the tire size, not by the weight on the tire). Motorcycles keep the contact patch large by using round cross sections for their tires so that the patch doesn't change when the bike leans. However, as I said before, the suspension can't handle bumps as well, and so rough curves suck far more on bikes than they do in cars.
 

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Thanks, wulfgang! I was reading that one of the reasons racing cars are faster/quicker than racing motorbikes is the aerodynamics, specifically the downforce. I presume it's very hard to create downforce on a motorcycle?
 
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