For what it's worth, in the above pic I was WOT, and no where near the cornering limits of this bike. I've slid the bike due to abrupt inputs, improper body position, and poor use of the throttle. Even at those lean angles, I've never found the limits of traction.

Quote from: burning1 on October 08, 2010, 06:28:10 PM

Quote from: twocool on October 08, 2010, 02:49:22 PM1 g seems high to me, but I'll take your word for that...................

That would give a lean angle of 45 degrees from the machine's center of gravity to the contact spot of the tire (side wall)

So you figure the same for braking?  1G ?   That would give some pretty short stopping distances...........

I have seen some test results for cars.......for braking.....and the .7 number seems about average....Seems like really good street tires do better, and racing tires go over 1G............



Cookie

Hi Cookie, yes, exactly... 45 degrees. Most bikes are capable of that, even on sport touring tires. That's with the rider on the centerline of the bike, obviously. The bike may lean more or less than 45 degrees at 1g, depending on the tire profile, CoG height, and the rider's body position.

Cars generate most of their grip from elastec restoration forces, the so-called slip-angle. Motorcycles make cornering force both from elastic restoration forces, and from camber thrust. In fact, camber thrust alone produces so much cornering force that at mild lean angles, many tires are actually running at a negative slip angle. Your typical motorcycle will out corner a car, despite what intuition would tell you about contact patch size.

Braking is limited more by the wheelbase of the bike and the CoG than it is by traction. There are some exceptions though: My GT is limited by tire traction. It'll also stop awfully fast; 1G is attainable.

Also keep in mind, that the traction circle is actually more of an oval than a circle. Moto tires create much more lateral cornering force than straightline force.

OK some interesting concepts.......I get what you mean about braking.....bike wil lift the rear tire off the ground before the front wheel is at max braking....

But this camber thrust.....Yes I understand how that works and how it turns a bike dirrerent than a car turns...but I am not convinced about that the general statement "your typical bike will outcorner a car".....IMHO it depends on what bike and what car..........for example cars with downthrust, like say F1....will develop way more than 1g or even more than 1.5g in turns......

You are not suggesting that camber thrust somehow creates better cornering than the coefecient of friction would normally allow?

Seems to me that in cornering you have to have some unbalanced lateral force (toward the center of the circle), in order to produce the acceleration..........now matter how this force is produced or created, it still is going to require the tire/road friction to hold it.........I could see that modern sport bike tires could give up to 1g or so........

Interesting to look at other "things" that use "lean" to turn.........Some boats, skier, ice skater, airplanes, human running, etc.......

Airplane is another hobby of mine............you would think that air is kind of "slippery" with little coeffecient of friction....yet 2 g turns in a plane is commonplace..........in fact up to 80 degree bank is still do-able at around 6g.

Only limit is the structrual strength of the airframe to hold up to that g loading, and the plane's ability to fly fast enough........

Fill me in on what I still missing about motorcycle turns!

Cookie

On the road, the limit is nearly always road surface conditions. What you can do on a nice clean track that you know is clean and clear ahead (since there are cornerworkers to warn you) and what you can do on a public road that may have gravel, oil, antifreeze, cow poop, leaves, water, small children, RV's stopped to take pictures of the foliage, or deer just out of sight ahead of you is perhaps somewhat different, unless you act like it isn't, until it is...

Under good conditions, the whole reason the footpegs are hinged is so that they will start to fold up and warn you that you are getting there as you lean. If you have something that sticks out farther than the footpegs that does not fold, it can pry you right off the tires in an instant (been there, done that, removed the poorly designed accessory, couldn't sit down for weeks, bought leather pants.) If you keep leaning until the footpegs run out of fold room or something else touches, same thing can happen.

If you fattened your rear tire, you can end up with odd effects as you lean way over and end up riding the sharp edge of a too-fat tire, with less rubber on the road than a stock tire.

But you can also be barely leaned over, hit a patch of gravel, and lowside on the ball-bearing effect. Wet leaves are about as slippery as ice.

Hanging off (various degrees of leaning you into the corner more than the bike is leaned) can help reduce the lean angle of the bike.

Far to many variables to be specific, just keep practising, you will soon find the bike`s (and your) limits for the situation.

Here is a tip.....When you get on your bike and before you put your gloves on hold out your right arm with your hand open and palm upwards in the horizontal. If after 20 or so seconds it becomes noticably wet......its safe to assume its raining and therefore banking in turns should be kept to the absolute minimum 

Cookie, it's not really fair to bring down-force into this conversation. Most consumer cars don't make appreciable down-force, and you're absolutely right that things start to change drastically as down-force comes into play.

If you're interested in the subject of Motorcycle traction, pick up a copy of Motorcycle Dynamics by Vittore Cossalter. My comments are based upon empirical testing described in that book... And the subject matter is covered at a depth I couldn't possible do justice to, here.

Quote from: burning1 on October 11, 2010, 11:58:20 AM
Cookie, it's not really fair to bring down-force into this conversation. Most consumer cars don't make appreciable down-force, and you're absolutely right that things start to change drastically as down-force comes into play.

If you're interested in the subject of Motorcycle traction, pick up a copy of Motorcycle Dynamics by Vittore Cossalter. My comments are based upon empirical testing described in that book... And the subject matter is covered at a depth I couldn't possible do justice to, here.

Thanks for the book recommendation.....

You're right about it being a complicated subject........If you search the internet all you get is simple physics explainations of the individual concepts.......never the whole complex deal at once.


Inquiring minds want to know....

Cookie

...Never-mind the amount of misinformation out there... You wouldn't believe how often I've debated the topic of motorcycle stability, counter steering in general, and low speed counter steering.

Motorcycle Suspension and Chassis Design by Tony Foale is also very good, BTW.

I believe it was Cossalter who described a motorcycle as a collection of simple components that interact in an incredibly complex way.

Interesting head-to-head from years ago: http://jsdproducts.com/Bike_Talk/References/Articles/Smackdown/smackdown.html

Quote from: burning1 on October 07, 2010, 06:24:57 PM
Seriously... You are the limitation, not the bike. Most crashes are caused by the rider exceeding their own abilities, rather than riders exceeding the limits of the bike.

Nailed it.

Is there a chicken strip thread with pics around here? I know that with a 130 rear tire, this bike will produce wear marks right off the lip of the tire in "normal"  riding conditions. I'll get some picks later.

I'm well off the edges of the rear, and about .5 millimetres from the edges of the front tire. To be honest, I feel like kind of a panzy out there. I'm pretty sure I could get an elbow down on my GS.

A vid for you here - http://gstwins.com/gsboard/index.php?topic=54250.msg611470#msg611470