Lizard928

jim that is great

Old & New

heinrich,

Why do you think that there is no weight on the rear tire? Under acceleration, most of the weight is on the rear tire.

heinrich

Old&New, for the Viper, there is somewhere in the area of 3,000lbs on the rear tyres under hard acceleration (a wild guess) ... what's the max weight the rear tyre of the bike sees?

Old & New

All of it!

No inference can be made from that one parameter alone... you must also consider that the bike & rider weigh less, so it becomes a function of (at least):

vehicle weight / weight on tires / contact patch

which is beyond me.

heinrich

Agreed, beyond me too... let's go drive/ride

bcdavis

Hahahaha!

Yeah!

Most of the articles I have read in bike mags, about these insane bikes, indicate they *do* have problems with traction, and with wheelies. And it's a problem you don't have with most cars. When you are at a standstill, with a powerful bike, you have a similar problem that a powerful car does. Traction. You either break the tire loose, or you do a wheelie. Neither one is good for acceleration. You have to be gentle with the gas, or you end up on your ***. (Rhymes)

So I don't know if those bikes were having traction issues or not. But they very well might have been holding back a bit. Because I know it is possible to do a power wheelie at 100mph with less powerful bikes. So with that much power, I am guessing they do not hit the throttle with full force. Of course I am sure it's the same with the car. I doubt they could downshift and punch it to the floor, without the car lighting up the tires. I'm guessing that is why they decided to race from 90mph. If they started from a standstill, it would be all about controling wheelspin, not about horsepower. It would leave the race much more in the hands of driver and rider skill, not as much reliance on the machinery to win the race for you.

Anyhow, there is always someone with something faster.

Regarding the track record at Willow for a bike, that is still damn fast.
And yes, a cart or indy car will handle better, and brake better,
and has similar power to weight, so they will do well on the track.
I was referring to regular street cars. When I say a bike will do
a 9 second quarter mile, or that it will do those times at Willow,
I am talking about a bike you can buy at the dealer. For about
$10,000. Not some $500,000 race car. Like I said, it is not very
likely you will meet a car like that Viper on the street. But people
come out of motorcycle showrooms every day with Hayabusas
that can hang with that Viper, and ZX-9's that can do 9 second
quarter miles. In stock configuration. If they add turbos, nitrous,
stroker cranks, and other mods, almost any street car will be
in trouble. Unless you see a lot of cart or indy cars on the street...

I don't deny that something that weighs 100 pounds, with 800hp,
and 4 wheels, will not be faster than a bike. A "car" like that
will do much better. But most modified street cars could not
hang with most sportbikes off the showroom floor...

DR

>You think that the bike's tire was breaking traction at over 100 mph???
>(Seems kind of unlikely.)

IF you get a chance, watch a replay of this years Daytona 200. There was a lot of discussion about problems with the Superbikes spinning their tires on the tri-oval when they got above 165-175mph !!!!

I have personally seen almost all the top Superbikes spinning their rear tires down the back straight of Road Atlanta at 150+

Jim Nowak

"Like I said, it is not very likely you will meet a car like that Viper on the street."

You must not live in the South. There are many people that drive their super street drag cars on the weekend to the local hot rod gatherings. These cars will absolutely eat bikes for breakfast. Yes, we all know that it is very difficult to beat a bike with a car in stock trim but bikes do not have the potential to go as fast or handle as well as cars. A Toyota S production class car still ran faster than any bike has ever run at Willow Springs.

A bike is very fast in production trim but cars can be made to go faster and handle better. I like bikes too and have a whole lot of respect for the speed and ability of a factory racing bike. Heck, I grew up in the same neighborhood as Freddy Spencer and I remember him when he was just riding dirt bikes for team Honda. I grew up riding bikes every day but I know the limits of a bike and cars can easily go past those limits.

bcdavis

I live in SoCal, and most of the cars you race here are ricers, or exotics with inexperienced drivers. Not too many pro-street or super street type hot-rods on the roads. But you will run into Ferarris and Vipers and Corvettes and Mercedes and Audis, and BMWs all the time. And, as I mentioned, lots of ricers. 300Zs, Supras, etc...

And I have never had any competition for my bike from any of them.

But like I said, there are not many 1,500-2000 horsepower hemis and big blocks running around the streets of LA, with big meaty drag tires in the back... So my impression of bikes being much faster than most street cars, is from real world experiences. But only in *my* neck of the woods. Maybe it is such a big place, you just do not run into the cars that would really be a contest. It's just that I usually leave most of those street cars like those Hyabusas left that Viper. Like they were standing still.

Old & New

DR,

Watch the video in the timeframe 12:45 to 13:00. The RPMs and speedometer are smooth & linear during acceleration all the way up. This is why I am under the impression that the tire is not losing traction.

I think the phenomenon you are describing is when the horsepower required to fight the air resistance exceeds the amount which can be put down through the rear tire contact patch.