Which corners faster - car or motorcycle?

[rcgldr]

When it comes to race tracks, the issue is the bikes much greater power to weight ratio versus a track car's better cornering. At Willow Springs, a 1 liter sport bike with an expert rider can run 1:27's, much faster than most classes of sports cars, mostly because Willow Springs is a high speed track. The bikes are slower in the turns, but that actually allows them to take a more parabolic line and accelerate out of the turns faster. On turns less than 90 degrees, the bikes can achieve similar cornering times even though peak cornering force is down (braking is the same, acceleration is much greater). However a moderate to high downforce car with good power like a Radical SR8 or Formula 3000 is going to dominate any motorcyle.

 

[mender]

And if that 1.3g figure mentioned is accurate there's plenty of thrill in there.

Here's that same graph but with numbers this time:
http://www.sportrider.com/tech/146_1001_g_force_plot_motorcycle_chains/index.html
I should have mentioned before that I was referring to competition tire compounds on well prepared vehicles for the comparison between cars and bikes. I felt that would reduce the variables sufficiently.

I noticed the big difference seems to be in braking capability, with the bike being considerably lower than the car as evidenced in the video. I couldn't find a traction circle for a car (I have generated lots while testing) to link but cars fill out the braking/cornering part of the graph much more so than the above bike graph shows. I double-checked the separated data here to make sure other issues weren't disguising the result:
http://www.docmc.net/index.asp?catid=6&id=90

I don't race bikes but I do race cars and filling out the lower quadrants of the traction circle makes quite a difference in lap times. It doesn't look like a bike is capable of that; true?

And again, steady state cornering capability seems to be very similar for bikes and cars.

 

[rcgldr]

And if you want a video try this one.http://www.youtube.com/watch?v=_UDXcotDqDs"

Another, this time R6 (600 cc instead of 1 liter bike) versus GT3:



Ducati 999 versus Gallardo:


Lap times at Willow Springs, fastest bikes are a bit over 1:19, about the same as GT1 race cars:

http://www.trackpedia.com/wiki/Will...rcycle_Lap_Records_.282.5_mile_Road_Course.29

However the high end tracks cars are faster:

http://www.willowspringsraceway.com/trackinformation/records.asp

 

[rhody]

I saw this http://www.youtube.com/watch?v=WaWoo82zNUA&feature=related" long ago, but with the current discussion, I think it is useful to bring up again, the Atom is extremely light weight produces 600 bhp per ton, and is a blast to drive.

Note: around the 3:00+ minute mark, without a helmet, how the drivers face becomes distorted from the wind. A key ingredient to this equation in the car to bike race (vs Honda CBR600RR) is the cars light weight and great brakes. The Ariel beat the bike by 4 seconds, the car costs 29,000 British pounds and it beats a 500,000 lb Carrera GT. So light weight, a wide wheel base, and from what you see the tires are not super wide or super tall, but perfect for the light weight of the Atom. They Ariel folks recommend the heavy duty brake package as well.

Here are the http://www.arielatom.com/specs/atom-3-specs" for the Ariel 3 from their website, there must be some information here, sacred geometry if you will that makes this almost the best handling car in the world, worth a look, IMHO.

Rhody...

 

[mender]

The numbers on their site work out to 434 hp/ton (4.6 lb/hp). No specs on the suspension geometry but I doubt there are any secrets to be had.

One of my personal projects (if I can ever get to it) will have about 4 lbs/hp and should outdo the Atom at 1/10th the cost - lots of scrounging involved!

 

[rhody]

The numbers on their site work out to 434 hp/ton (4.6 lb/hp). No specs on the suspension geometry but I doubt there are any secrets to be had.

One of my personal projects (if I can ever get to it) will have about 4 lbs/hp and should outdo the Atom at 1/10th the cost - lots of scrounging involved!

Mender,

I was quoting the author in the video, but even at 434 hp per ton, it is quite impressive. Good luck with your project, if and when you get around to it, promise to give us PF folks a sneak peak when you complete it.

Rhody...

 

[mender]

The most I've driven on the street (customer's car in for some upgrades) was just under the 4lb/hp mark; very addictive! That's the reason for setting the target at that mark.

I checked some other sites and their numbers (like the author's) seem to be based on a curb weight of 1050 to 1100 lbs as opposed to the Atom listing of 1350 lbs. Any reason for the discrepancy? And in the video, again the bike lost under braking.

I didn't see much lean angle on the bike in the corners so I'll assume that it had street tires. What do they typically corner at?

 

[rhody]

I didn't see much lean angle on the bike in the corners so I'll assume that it had street tires. What do they typically corner at?

mender,

That is not an easy question to answer, the best I can give is that a set of racing slicks, properly warmed, in a special compound called a "qualifier" compound are super sticky and provide the best cornering grip and acceleration out of a corner. The problem is the "qualifier" tire is only good for one lap at most motogp tracks.

I have read that (in Sportrider magazine I believe) with an expert rider a super bike can corner with a little over 1g of lateral acceleration, and accelerate and decelerate (at maximum) with about +.8g's and -.8g's respectively, on sticky street tires.

Rhody...

 

[rcgldr]

I have read that (in Sportrider magazine I believe) with an expert rider a super bike can corner with a little over 1g of lateral acceleration, and accelerate and decelerate (at maximum) with about +.8g's and -.8g's respectively, on sticky street tires.

That would conflict with their own drag race testing where the top bikes are averaging over 1 g in acceleration in 0 to 60 mph tests (less than 2.75 seconds). A few braking tests have also shown them to be over 1 g. Lateral acceleration is usually less on a bike than braking or peak acceleration in first gear.

In the car versus bike tests, generally the bikes are braking sooner, not with less deceleration, because the bikes corner entry speeds are lower.

 

[mender]

Yet this shows otherwise:
http://www.docmc.net/index.asp?catid=6&id=90
The cornering gs are around 1.3 but the braking, even in a straight line, never exceeds 1 g. Trail braking is even worse, and that shows up in every video of car vs bike.

The bike is definitely decelerating at a lower rate, which is why the car goes by under braking even though they enter and are going through the corner at roughly the same rate. If the bike braked at the same rate, the time interval would stay the same to corner entry.

 

[rhody]

That would conflict with their own drag race testing where the top bikes are averaging over 1 g in acceleration in 0 to 60 mph tests (less than 2.75 seconds). A few braking tests have also shown them to be over 1 g. Lateral acceleration is usually less on a bike than braking or peak acceleration in first gear.

In the car versus bike tests, generally the bikes are braking sooner, not with less deceleration, because the bikes corner entry speeds are lower.

rcgldr, mender,

Perhaps the +.8g and -.8g for acceleration and deceleration is the "average" overall acceleration. Everyone who rides knows that in first, second gear the bike accelerates quicker than it does in the higher gears. As you and mender correctly observe, there seems to be no general consensus on how these numbers are arrived at. A truly honest way would list the data collection methods and mathematics used to produce their results. Then one has a benchmark to compare the data, without this, it is impossible to determine with true accuracy, no ?

We have seen cases in this thread where a bike beats a car on the track, and vice versa. In the end it comes down to weight, ability to deliver grip to the pavement, tire compound, construction and footprint, the hp/torque curves of the car and bike being run head to head, the type of track and track surface and the skill of the driver which allows one type of vehicle to shine over the other in the comparision.

Rhody...

 

[rcgldr]

Yet this shows otherwise:
http://www.docmc.net/index.asp?catid=6&id=90
The cornering gs are around 1.3 but the braking, even in a straight line, never exceeds 1 g.

That graph is showing accelerations as experienced on a particular race track. Looking at the graph, the maximum braking occurs while also cornering, apparently that particular track doesn't have much straight line braking.

The tests I've seen for street motorcycles show braking deceleration rates of .8 g to a bit over 1.0 g, which I assume is related to the bikes being tested, the pavement involved, and the riders. Racing motorcycles with slicks have much higher decleration rates, but I'm unable to find any articles at the moment. I seem to recal 1.5+gs, but that was at high speeds where aerodynamic drag is assisting the rate of deceleration.

 

[rhody]

That graph is showing accelerations as experienced on a particular race track. Looking at the graph, the maximum braking occurs while also cornering, apparently that particular track doesn't have much straight line braking.

The tests I've seen for street motorcycles show braking deceleration rates of .8 g to a bit over 1.0 g, which I assume is related to the bikes being tested, the pavement involved, and the riders. Racing motorcycles with slicks have much higher decleration rates, but I'm unable to find any articles at the moment. I seem to recal 1.5+gs, but that was at high speeds where aerodynamic drag is assisting the rate of deceleration.

rcgldr,

That seems reasonable, but a bit on the high side, while you are searching, can you come up with a formula or example of how much force is transmitted to your arms under maximum braking. I have been claiming it is between 200 - 300 lbs of force, but that is from seat of the pants feel hauling my FJR down from say 80+ mph, and that is without slicks. She is a heavy beast too, so I imagine a sportbike that weighs 150 lbs less would stop a heck of a lot quicker, exerting even more deceleration force. I will do a little digging myself to see what I can come up with as well.

Rhody...

P.S. I have seen many video's of racers hard on the brakes from 150+ down to 75+ in about 4 seconds, have a look http://www.youtube.com/watch?v=NKURNzl7cSY&feature=related" to see what I am talking about. The last video with Nate Kern you can tell he is max on the brakes because the front end is squirming under the load and the handle bars are making the classic figure eight pattern as he applies max braking, which BTW is linked to the rear as well from the front brake lever. I have a 2011 BMW 1000RR so I can verify this. Used by itself with the right foot pedal, not much braking force is felt, that is by design, a sport bike is a twitchy thing to begin with and adding a sensitive rear brake is just asking for trouble, it is mainly used to keep the rear wheel from lifting and to allow minor adjustments to your line mid corner if needed.

 

[mender]

That graph is showing accelerations as experienced on a particular race track. Looking at the graph, the maximum braking occurs while also cornering, apparently that particular track doesn't have much straight line braking.

If you look at the graph right after turn #2, the max braking on the entire graph is occurring with a peak of about .9 gs as the bike is transitioning; very little cornering happening right then. Point made about the track however.

A friend of mine does chassis tuning and data acquisition for some of the better European riders; I'll see if he's willing to enlighten me.

 

[mender]

P.S. I have seen many video's of racers hard on the brakes from 150+ down to 75+ in about 4 seconds, have a look http://www.youtube.com/watch?v=NKURNzl7cSY&feature=related" to see what I am talking about.

The first example works out to an average of 0.85 gs and the second to 0.74 gs, but the margin of error is quite large.

Given the high C of G of bike and rider and the forces acting on the bike when braking, there will be a well-defined limit to the braking before lifting the rear wheel. Cornering isn't limited by that, as stated earlier.

 

[rcgldr]

Given the high C of G of bike and rider and the forces acting on the bike when braking, there will be a well-defined limit to the braking before lifting the rear wheel. Cornering isn't limited by that, as stated earlier.

That could be an issue, you do see the rear wheel getting light and hopping under heavy braking on racing motorcyles, and a lot of sport bikes can do stoppies. I'm not sure of front to back weight distribution on a racing motorcycle or sport bike. Almost all bikes can do wheelies, but I'm not sure what percentage can do stoppies. Regarding my comment about 1.5 g's under braking, I think that was deceleration from 180mph, with a lot of aerodynamic drag, it was from some video about motorcycle racing.

Getting back to the original question, all things being somewhat equal, a car will have an advantage with cornering grip, since the larger amount of contact patch area translates into a lower load factor per unit area of the tires. The bikes are faster at some race tracks because they have a higher power to weight ratio than all but the high end race cars, and they compensate for slower cornering speeds with faster speeds on the straights.

 

[rhody]

rcgldr,

Almost all bikes can do wheelies, but I'm not sure what percentage can do stoppies.

The answer is all bikes (those without ABS) and an experienced rider can do stoppies, here is a http://www.youtube.com/watch?v=7qaK1E6BV_0" a wheelie at 150+ in the pouring rain. I checked and it appears Ghostie is still with us, not sure if he is still up to his evil ways however, sooner or later his luck is bound to run out.

Rhody...

P.S. I found this as to the true identity of ghost rider, take it for what it is worth:

Motorcycle news recently revealed the true identity of Ghost Rider as Swedish rider Patrik Furstenhoff (a member of the Swedish Wheelie Team - SWT) when he broke the world wheelie speed record, breaking his own previous record by 14 mph to record 215 mph on one wheel!

Here is a http://www.google.com/images?hl=en&...&aq=1&aqi=g-sx1g1&aql=&oq=Patrik+Furstenhoff" to images of him, if in fact it is him, which I suspect it is because of his height, body type, which closely matches the guy in the photo to the rider in his video's.

 

[mender]

Getting back to the original question, all things being somewhat equal, a car will have an advantage with cornering grip, since the larger amount of contact patch area translates into a lower load factor per unit area of the tires.

As I said earlier, the air pressure in the tire supports the vehicle (mostly) and determines the contact patch area, found by dividing the vehicle weight by the tire pressure. If different vehicles use roughly the same tire pressures, the load/area ratio will also be the same.

The car that I take care of usually comes in at about 35 psi hot all around on the road course; I just talked to my friend and he was saying that their pressures are about the same on the front but around 25 psi on the rear.

That means that those bikes have a lower load/area ratio than the car.

 

[mender]

rcgldr,The answer is all bikes (those without ABS) and an experienced rider can do stoppies, here is a http://www.youtube.com/watch?v=7qaK1E6BV_0" to the current world record holder for stoppies, 137 mph, by Kane Friesen (note: Kane's parents are watching as he does this !) and one for the fastest wheelie, 214 mph by the infamous ghost rider.

Wow! That's nuts!
Uh, what're the records for an '83 RZ350? I need some reasonable goals!
Actually, no I don't 'cause as I said I race cars, not bikes!