Max G rating of a motorcycle? - LotusTalk - The Lotus Cars Community
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 23 (permalink) Old 08-01-2007, 06:01 AM Thread Starter
Registered User
 
Lotus Fury's Avatar
 
Join Date: Apr 2003
Location: Pgh, Pa
Posts: 2,262
Max G rating of a motorcycle?

Question at work: What is the max G rating of a bike? We were talking about the Ariel Atom versus Motorcycle video from Top Gear. I know with most cars sans aero help maxed out it's around 1.5 or so with super sticky tires. But what about motorcycles? I searched the internet to no avail.
Lotus Fury is offline  
Sponsored Links
Advertisement
 
post #2 of 23 (permalink) Old 08-01-2007, 06:33 AM
Registered User
 
Conan's Avatar
 
Join Date: Jul 2006
Location: San Antonio, TX
Posts: 2,379
Quote:
Originally Posted by Lotus Fury
Question at work: What is the max G rating of a bike? We were talking about the Ariel Atom versus Motorcycle video from Top Gear. I know with most cars sans aero help maxed out it's around 1.5 or so with super sticky tires. But what about motorcycles? I searched the internet to no avail.
Bikes have only 2 very small tire contact patches to work with, so they won't pull anywhere near what a car does. They also won't brake nearly as a well either for the same reason. However, they kick the crap out of cars for acceleration.

Fast in, fast out.
2013 Mini Cooper S, 2007 Honda Odyssey (the wife's), gone: 2006 Elise
Conan is offline  
post #3 of 23 (permalink) Old 08-01-2007, 06:46 AM Thread Starter
Registered User
 
Lotus Fury's Avatar
 
Join Date: Apr 2003
Location: Pgh, Pa
Posts: 2,262
That was the discussion - what tracks would a motorcycle have the advantage versus the cars? Any long straight tracks and the car would have to be very close in weight/HP. Curvier tracks would give a car with great handling/aero help the advantage. But it came down to the fact that even the motorcycles guys had no idea how many G's their bikes could pull.

Needless to say this wasn't one of our more productive workday discussions...
Lotus Fury is offline  
 
post #4 of 23 (permalink) Old 08-01-2007, 07:17 AM
Registered User
 
milcher's Avatar
 
Join Date: Nov 2003
Location: Gilbert, AZ
Posts: 363
For bikes, the tangent of the lean angle is the g's for that turn.

Earlier in the year during the MotoGP (top level of MC racing) TV broadcast, onscreen telemetry showed John Hopkins reaching 56 degrees of lean (from straight up). This equates to 1.48 g's. This past race, the winner Casey Stoner showed 63 degrees of lean going thru the corkscrew at Laguna Seca. 63 degrees equates to 1.96 g's. Banking in the corkscrew allowed for more lean than what could be achieved on a flat turn.

The 2007 Yamaha R6 is designed with a max of 57 degrees of lean. With a very good rider on the track, in a flat turn riding a current 600cc sportbike and using racing tires, I would expect a reasonable max lean to be about 55 degrees. 55 degrees of lean would be 1.43 g's.

Gary M
Gilbert, AZ
milcher is offline  
post #5 of 23 (permalink) Old 08-01-2007, 07:18 AM
Registered User
 
chrisp993's Avatar
 
Join Date: Jul 2006
Location: Bloomfield Hills, MI
Posts: 337
Cars without aero help max out ON A LEVEL FLAT SURFACE at very slightly over 1g - owing to some straightforward physics plus a bit of rubber chemistry. In a slightly banked corner, or compressing into the beginning of a hill etc. its easy to hit 1.4 to 1.5 g, but that's different to the level surface idea.

Now someone needs to explain why the same argument doesn't hold for bikes!
chrisp993 is offline  
post #6 of 23 (permalink) Old 08-01-2007, 07:37 AM
Registered User
 
Conan's Avatar
 
Join Date: Jul 2006
Location: San Antonio, TX
Posts: 2,379
Quote:
Originally Posted by chrisp993
Cars without aero help max out ON A LEVEL FLAT SURFACE at very slightly over 1g - owing to some straightforward physics plus a bit of rubber chemistry. In a slightly banked corner, or compressing into the beginning of a hill etc. its easy to hit 1.4 to 1.5 g, but that's different to the level surface idea.

Now someone needs to explain why the same argument doesn't hold for bikes!
What argument? Those rules still apply to bikes. They just have less of that rubber chemistry biting the ground. The "bikes vs cars" thing has been done over and over. This is hijacking the thread a bit since the OP wanted a cornering g-force range for bikes, which I don't have. But cars with similarly equipped tires (R-compounds on bike vs R-compounds on car) will always out brake and out corner a bike, even sans aero.

Fast in, fast out.
2013 Mini Cooper S, 2007 Honda Odyssey (the wife's), gone: 2006 Elise
Conan is offline  
post #7 of 23 (permalink) Old 08-01-2007, 07:38 AM
Registered User
 
Join Date: Dec 2006
Location: Dayton, Ohio
Posts: 663
Quote:
Originally Posted by milcher
For bikes, the tangent of the lean angle is the g's for that turn.

Earlier in the year during the MotoGP (top level of MC racing) TV broadcast, onscreen telemetry showed John Hopkins reaching 56 degrees of lean (from straight up). This equates to 1.48 g's. This past race, the winner Casey Stoner showed 63 degrees of lean going thru the corkscrew at Laguna Seca. 63 degrees equates to 1.96 g's. Banking in the corkscrew allowed for more lean than what could be achieved on a flat turn.

The 2007 Yamaha R6 is designed with a max of 57 degrees of lean. With a very good rider on the track, in a flat turn riding a current 600cc sportbike and using racing tires, I would expect a reasonable max lean to be about 55 degrees. 55 degrees of lean would be 1.43 g's.
OK, so what you are stating is that my 06 harley ultra classic (getting a 08 in a few months) would be able to acheive -.8g's due to it not being able to lean at all

Seriously though, what would the R6 that does 1.43g on track tires do with some good street tires? Would it break 1g? Don't sport bikes do 60-0 in under 100ft?
Viggen is offline  
post #8 of 23 (permalink) Old 08-01-2007, 07:40 AM
Registered User
 
Conan's Avatar
 
Join Date: Jul 2006
Location: San Antonio, TX
Posts: 2,379
Quote:
Originally Posted by Conan
What argument? Those rules still apply to bikes. They just have less of that rubber chemistry biting the ground. The "bikes vs cars" thing has been done over and over. This is hijacking the thread a bit since the OP wanted a cornering g-force range for bikes, which I don't have. But cars with similarly equipped tires (R-compounds on bike vs R-compounds on car) will always out brake and out corner a bike, even sans aero.
Let me add a few more axioms: Car is an equivalent version of the bike. ie: Yamaha R1 = Arial Atom/Ferrari F430/Z06 Corvette/ etc. I think an R1 is going to out brake and out corner a Yugo, for instance, because they aren't really comparable.

Fast in, fast out.
2013 Mini Cooper S, 2007 Honda Odyssey (the wife's), gone: 2006 Elise
Conan is offline  
post #9 of 23 (permalink) Old 08-01-2007, 07:44 AM
Forum Founder
 
Randy Chase's Avatar
 
Join Date: Apr 2002
Location: Tail of the Dragon
Posts: 29,083
Garage
Quote:
Originally Posted by chrisp993
Cars without aero help max out ON A LEVEL FLAT SURFACE at very slightly over 1g - owing to some straightforward physics plus a bit of rubber chemistry. In a slightly banked corner, or compressing into the beginning of a hill etc. its easy to hit 1.4 to 1.5 g, but that's different to the level surface idea.

Now someone needs to explain why the same argument doesn't hold for bikes!
I can hit over 1.4 on a level flat surface, depending on type of tires I use.

#somethingwickedthiswaycomes... the new Origin Noble M and the Origin 7

Zenos E10S for Sale! www.zenosforsale.com

There are some very shady dealers in the Lotus business.

2005 Lotus Elise, 1993 MR2, 1995 MR2, 125cc Shifter Kart, Toniq (in build), 2018 Origin 7 (waiting), 2018 Origin Noble M (waiting)
Randy Chase is offline  
post #10 of 23 (permalink) Old 08-01-2007, 10:54 AM
xtn
Registered User
 
xtn's Avatar
 
Join Date: May 2006
Location: Texas
Posts: 6,981
If the road is really smooth and flat, then the size of the contact patch doesn't make much difference. The maximum G level obtainable will be dependant upon:

#1. The coefficient of friction between the rubber and the road.

#2. The suspension's (including tire sidewall) ability to keep the contact patch in a stable and usable condition while subject to the forces of that maximum loading.

Now assuming you were willing to pay for a new set of very expensive tires every ten miles, I'm sure one of the companies could produce a sticky enough compound to get a suitably suspensioned car up into the 3G range sans aero. Same goes for a motorcycle if it was physically designed to lean over at 72deg and retain a stable contact patch.

I don't think the lean angles mentioned by milcher take into consideration the fact that the rider is shifting the CG by hanging his body off. So the G-forces mentioned are actually calculated a bit lower than really achieved.

xtn

2006 McLareghini Bugatterrari, Storm Titanium... installed: air horn, Scroth 4-point ASM harnesses, Sector111 halon extinguisher and mounting bracket, Von Hep exhaust and rear panel delete, Pagid brake pads, red Volks CE28n wheels, Toyo RA-1 tires, Nitron SA coilovers, Sector111 (WorksBell) quick-disconnect steering wheel kit. awaiting installation: Scroth "pull-up" lap belts, Sector111 RTD Brace, Tony's heater bypass mod, and dropped steering rack mounting plates.
xtn is offline  
post #11 of 23 (permalink) Old 08-01-2007, 12:22 PM
Registered User
 
codymac's Avatar
 
Join Date: Nov 2005
Location: where the east tapers out and the west begins
Posts: 9,297
For a nice simplified overview, see Gaetano Cocco's books.

I've lost track of the physicist's name that consults with a lot of Italian manufacturers, but he used to have an excellent site with lots of formulas and resources on it. An older gentleman who has spent most of his life figuring out how motorcycles work as systems (not all the questions have been adequately answered).

And there's always Tony Foale's work.

torque (trk) n. - an excuse for the lack of momentum.
- let's bring back CanAm & Group B!
- have you hugged your Exige today?
I'm currently working on my performance driving merit badge.
There's always somebody faster, sometimes it's me.
codymac is offline  
post #12 of 23 (permalink) Old 08-01-2007, 02:07 PM
Registered User
 
chrisp993's Avatar
 
Join Date: Jul 2006
Location: Bloomfield Hills, MI
Posts: 337
Ummm, Randy, no you can't - unless there is some banking to the corner. I've got plenty of data logged at 1.4g to 1.5 g but always at the bottom of a hill or on some slope.

Witness all the magazine skid pad tests that never really go over 0.95g to 1.05 g for a practical evidence, but the real theory is that as xtn said, the maximum g is proportional to the coefficient of friction - and that is always less than 1. Put another way, absent any actual molecular level sticking to the ground - which is never going to be more than a small amount - simple friction can't resist more sideways force than the weight pressing down.
chrisp993 is offline  
post #13 of 23 (permalink) Old 08-01-2007, 02:17 PM
Forum Founder
 
Randy Chase's Avatar
 
Join Date: Apr 2002
Location: Tail of the Dragon
Posts: 29,083
Garage
Flat surfaces. Testing between different tires. Put fresh slicks on the data logger's accelerometers report 1.4gs. No elevation. No banking. Skid pad.


#somethingwickedthiswaycomes... the new Origin Noble M and the Origin 7

Zenos E10S for Sale! www.zenosforsale.com

There are some very shady dealers in the Lotus business.

2005 Lotus Elise, 1993 MR2, 1995 MR2, 125cc Shifter Kart, Toniq (in build), 2018 Origin 7 (waiting), 2018 Origin Noble M (waiting)
Randy Chase is offline  
post #14 of 23 (permalink) Old 08-01-2007, 04:08 PM
xtn
Registered User
 
xtn's Avatar
 
Join Date: May 2006
Location: Texas
Posts: 6,981
Quote:
Originally Posted by chrisp993
Ummm, Randy, no you can't - unless there is some banking to the corner. I've got plenty of data logged at 1.4g to 1.5 g but always at the bottom of a hill or on some slope.

Witness all the magazine skid pad tests that never really go over 0.95g to 1.05 g for a practical evidence, but the real theory is that as xtn said, the maximum g is proportional to the coefficient of friction - and that is always less than 1. Put another way, absent any actual molecular level sticking to the ground - which is never going to be more than a small amount - simple friction can't resist more sideways force than the weight pressing down.
You're quite wrong.

Those tests you're discussing are on OEM tires or other DOT street legal tires at least. You put some good racing slicks on, and equip the suspension to keep the contact patches usefull under the higher loads, and those same cars will run 1.3 to 1.4 Gs all day long. Under the most optimum conditions the stickier tires have coefficients in the neighborhood of 1.7 against good concrete.

2006 McLareghini Bugatterrari, Storm Titanium... installed: air horn, Scroth 4-point ASM harnesses, Sector111 halon extinguisher and mounting bracket, Von Hep exhaust and rear panel delete, Pagid brake pads, red Volks CE28n wheels, Toyo RA-1 tires, Nitron SA coilovers, Sector111 (WorksBell) quick-disconnect steering wheel kit. awaiting installation: Scroth "pull-up" lap belts, Sector111 RTD Brace, Tony's heater bypass mod, and dropped steering rack mounting plates.
xtn is offline  
post #15 of 23 (permalink) Old 08-01-2007, 04:40 PM
Registered User
 
Join Date: Jul 2003
Posts: 6,602
Quote:
Originally Posted by xtn
I don't think the lean angles mentioned by milcher take into consideration the fact that the rider is shifting the CG by hanging his body off. So the G-forces mentioned are actually calculated a bit lower than really achieved.

xtn
That is exactly correct! The lean angle method is accurate only if the driver is centered on the motorcycle, otherwise it is an underestimate. BTW, I still remember the first time my knee puck touched pavement... sizzle... panic... realization... awe...

Thomas

The new owner of RLS is Austin, you can contact him at: Austin0Barrett <<<< @ >>>> gmail <<<< dot >>>> com
Thomasio is offline  
post #16 of 23 (permalink) Old 08-01-2007, 04:41 PM
Registered User
 
Join Date: Jul 2003
Posts: 6,602
Quote:
Originally Posted by codymac
And there's always Tony Foale's work.
Tony F! Yes, he's a good guy. I corresponded w/ him after a motorcycle accident in 2000. Good texts, too.

By the way, I swore off riding motorcycles then... "but I'm getting a Lotus!"

Thomas

The new owner of RLS is Austin, you can contact him at: Austin0Barrett <<<< @ >>>> gmail <<<< dot >>>> com
Thomasio is offline  
post #17 of 23 (permalink) Old 08-01-2007, 04:53 PM
Registered User
 
codymac's Avatar
 
Join Date: Nov 2005
Location: where the east tapers out and the west begins
Posts: 9,297
Found the site:
http://www.dinamoto.it/DINAMOTO/on-l..._eng/Tires.htm


http://www.dinamoto.it/DINAMOTO/rese.../tire-test.htm

And... as measured on a simulation rig:
Attached Images
 

torque (trk) n. - an excuse for the lack of momentum.
- let's bring back CanAm & Group B!
- have you hugged your Exige today?
I'm currently working on my performance driving merit badge.
There's always somebody faster, sometimes it's me.

Last edited by codymac; 08-01-2007 at 04:59 PM.
codymac is offline  
post #18 of 23 (permalink) Old 08-01-2007, 05:07 PM
Registered User
 
Stephen's Avatar
 
Join Date: Jul 2005
Location: West of Mississippi
Posts: 1,888
I have read a few articles in the past with street bike and street car comparos (ZX-7R vs. Ferrari F40 or something similar, I can't remember exactly). They were both the high performance versions of bike and car for the street, and both using street tires. I always remember the outcome being the same. The car would pull away from the bike on the corners, and the bike would pull away from the car on the straights; I don't remember the braking distances. If it was a curvy tight track, the car would win; if it had a lot of straights, the bike would win. I think I probably read at least 3 articles like this with the same results.

I also seem to remember one article that actually had the G forces. The car was somewhere in the high .90's and I seem to remember the bike being somewhere in the .70's. They always said that four flat contact patches was better than two curved ones with the ability to lean.

My guess is that this still holds true as long as you keep the machines and their relevant parts equal, i.e. if one uses racing slicks, then both should; or if one is a "real" sports car, then the other needs to be a sport bike.

In my personal street experiences (I have never raced against a bike on a track), there have been times where I am on the highway and have a long sweeper or just a little canyon run and it is at a time when it is safe to push the car to 8/10's because of no traffic close to me. And occasionally I have had a car or bike behind me trying to keep up (this has happened with me driving my Fiero, my Focus SVT, my Boxster/Cayman/911, or my Elise/Exige). When it was another car, I would leave them in the dust in cornering 95% of the time (this is due to many factors), but occasionally I would get the guy or gal who is also an enthusiast and they had an idea of what their car could do and they would keep up very well. But in all the cases involving bikes; they never came close. When it came time to take a corner, especially a long sweeper like I-25 Southbound to I-40 Eastbound, they would turn into a little dot, but then catch up in no time on the straight.

And for those of you who do not condone street racing; I do not approve of it either and will only do a friendly game of chase when I really feel it is safe and reasonable to do so. I would never do a side by side race on the street with cornering and weaving between cars. It basically has to be me and the other vehicle, and we are playing follow the leader with a good distance between us. And if it is a bike, it needs to be a guy in full leathers and a helmet, or I will not do it either. I don't want a kid who thinks he knows what he is doing try to keep up and then wreck their bike; I would feel very responsible if I knew they were trying to keep up.

Anyway, my point is that my own personal experiences in 20 + years of driving support the magazine tests that I have read. Cars win in the corners, bikes win on the straights.

2009 Mini Cooper JCW - Dark Silver/Black - sport suspension/cold weather package
2008 997 GT3 - Carrara White/Black - PCCB's - 350 lbs of weight reduction

Past Lotus Cars: 2005 NFB Elise, 2007 CO Exige S, 2005 AR Elise, 2008 CO Exige S 240
Stephen is offline  
post #19 of 23 (permalink) Old 08-01-2007, 05:24 PM
Registered User
 
codymac's Avatar
 
Join Date: Nov 2005
Location: where the east tapers out and the west begins
Posts: 9,297
Quote:
Originally Posted by Stephen
In my personal street experiences (I have never raced against a bike on a track), there have been times where I am on the highway and have a long sweeper or just a little canyon run and it is at a time when it is safe to push the car to 8/10's because of no traffic close to me. And occasionally I have had a car or bike behind me trying to keep up (this has happened with me driving my Fiero, my Focus SVT, my Boxster/Cayman/911, or my Elise/Exige). When it was another car, I would leave them in the dust in cornering 95% of the time (this is due to many factors), but occasionally I would get the guy or gal who is also an enthusiast and they had an idea of what their car could do and they would keep up very well. But in all the cases involving bikes; they never came close. When it came time to take a corner, especially a long sweeper like I-25 Southbound to I-40 Eastbound, they would turn into a little dot, but then catch up in no time on the straight.
My experiences, on bikes, with car drivers has generally been the opposite. Most drivers and riders have no idea what their vehicles are capable of - and most street riders are painfully slow. I know i certainly treat a track bike/race bike differently than I do one of my "babies."

torque (trk) n. - an excuse for the lack of momentum.
- let's bring back CanAm & Group B!
- have you hugged your Exige today?
I'm currently working on my performance driving merit badge.
There's always somebody faster, sometimes it's me.
codymac is offline  
post #20 of 23 (permalink) Old 08-01-2007, 07:11 PM
Registered User
 
stigg99's Avatar
 
Join Date: Apr 2007
Posts: 37
Not to thread jack but...

What is the coefficient of drag for a sport bike used in say, MotoGP?

And another thing i have been pondering lately is....

There is going to be a limit as to how streamlined something can be moving through the air. So what is the lowest Cd of drag that has been achieved and by what???

I konw that the koenigsegg has a Cd of something like a fish.... So what is the Cd of a shark then?? Would it be the same as the fish?

I've tried tons of searches for this kind of stuff but rarely do i find anything substantial. Someone really needs to make a motorcycle sight in the same style that Ultimatecarpage.com is designed.
stigg99 is offline  
Sponsored Links
Advertisement
 
Reply

  LotusTalk - The Lotus Cars Community > Community > Other

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the LotusTalk - The Lotus Cars Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome