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Old 01-03-2013, 05:05 PM   #81 (permalink)
CYD
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Quote:
Originally Posted by noamkrief View Post
Good to have you on board on this topic. It's clear you have an understaing of physics.

If I understand you correctly, you are suggesting that instead of having the end-user select a desire lean angle, that the user enter in their coefficient of friction of their tire. With that, I can truly find out what the TIRES are capable of and calculate the maxium speed through the turns...
I am not suggesting having coefficient of friction instead of lean angle. I think you need to have both as options.
Lean angle should be defined as the furthest you are comfortable/capable of leaning over. The Coefficient of Friction is a very rough guestimate in ideal situations. When calculating the max speed, it should be the lower speed of the two calculations between Max Lateral G/Angle and Coeffient of Friction/.
So if you max out the coefficient of friction at 45 degrees, but your comfort lean is 40 degrees, then take the lower speed at the given 40 degree angle. Otherwise if the coefficient of friction doesn't allow for speeds that require 40 degrees, then choose the lower speed that is allowed given the selected coefficient of friction. So it should calculate both values independently, and take the lower of the two. Therefore for each corner it should post the max speed AND the angle necessary for that speed. So in some corners the angle might be less than the max angle the bike is capable of...
That would be my suggestion.

Quote:
Originally Posted by noamkrief View Post
A few problems with that though:
1) Do tire manufacturers publish the coefficient of friction?
2) If so, can we trust them? Under what conditions? What type of pavement?
3) What if the coefficient of friction is so great that you hit the physical limit of the bike before the coefficient of friction is reached? What if full slick is capable of generating 2 lateral G's which would require a lean angle of 63 degrees but the bike is already dragging a footpeg at 55 degrees effective lean angle with the rider fulling hanging off the bike to increase his effective lean as much as possible?
1) Not all but some do, for certain cases that data can be extrapolated. The information for Lateral G's of tires can also be calculated from skid pad tests and lean angles. And there is also data for that somewhere. You would only need to take a few samples to make a simple dropdown with "average" differences.
i.e. Michelin Pilot Power Tires - RevZilla
Quote:
Unprecedented lean angles: 50.6 degrees in the dry, 41.9 degrees in the wet
Assuming tested at the Michelin test track you can get presumably calculate the coefficient of friction as 1.2 dry and .90 wet (source).
Whether there is more data, I am not going to bother looking, but that's a good start, go up and down from there

2) No more than we can trust the bank angle and google maps corner points
3) See note above...

Whether you change up your site or not, I think it's a useful tool after knowing it's current limitations (fixed assumptions etc...). I appreciate your consideration of my suggestions, and if you find my feedback insightful enough to change your site, I would be greatful for your additional efforts.

Cheers,
~CYD

Last edited by CYD; 01-03-2013 at 05:11 PM.
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Old 01-03-2013, 08:00 PM   #82 (permalink)
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All the website needs is a disclaimer stating that it's a general guide not a perfect calculator for how fast you should go. Like we've all agreed, there are too many variables to have the tool be any more than a starting point which I believe was the original intent. If you start adding coefficient of friction and tire makes and wet vs dry etc... I think it would get too confusing as well as misleading as far as its accuracy for real world application. Throw up a disclaimer and leave it at that.

Lastly, providing tools and information like the ones in this thread are part of what makes this a great website. But the personal attacks just devalue it in my opinion. Noam, again you should be thanked for providing us with this fun tool...but calling Rush's girl a skank was very immature and I feel you crossed the line there. I know we can all resort to emotional responses when we feel attacked but you always look better, and people always respect you more, when you take the high road. Love the cornering tool......let's keep this site friendly and fun!
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Old 01-03-2013, 10:40 PM   #83 (permalink)
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Quote:
Originally Posted by HULK View Post
All the website needs is a disclaimer stating that it's a general guide not a perfect calculator for how fast you should go. Like we've all agreed, there are too many variables to have the tool be any more than a starting point which I believe was the original intent. If you start adding coefficient of friction and tire makes and wet vs dry etc... I think it would get too confusing as well as misleading as far as its accuracy for real world application. Throw up a disclaimer and leave it at that.

Lastly, providing tools and information like the ones in this thread are part of what makes this a great website. But the personal attacks just devalue it in my opinion. Noam, again you should be thanked for providing us with this fun tool...but calling Rush's girl a skank was very immature and I feel you crossed the line there. I know we can all resort to emotional responses when we feel attacked but you always look better, and people always respect you more, when you take the high road. Love the cornering tool......let's keep this site friendly and fun!
I am with you on this one HULK.
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Last edited by Blackice; 01-03-2013 at 10:48 PM.
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Old 01-04-2013, 01:52 AM   #84 (permalink)
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Quote:
Originally Posted by CYD View Post
I am not suggesting having coefficient of friction instead of lean angle. I think you need to have both as options.
Lean angle should be defined as the furthest you are comfortable/capable of leaning over. The Coefficient of Friction is a very rough guestimate in ideal situations. When calculating the max speed, it should be the lower speed of the two calculations between Max Lateral G/Angle and Coeffient of Friction/.
So if you max out the coefficient of friction at 45 degrees, but your comfort lean is 40 degrees, then take the lower speed at the given 40 degree angle. Otherwise if the coefficient of friction doesn't allow for speeds that require 40 degrees, then choose the lower speed that is allowed given the selected coefficient of friction. So it should calculate both values independently, and take the lower of the two. Therefore for each corner it should post the max speed AND the angle necessary for that speed. So in some corners the angle might be less than the max angle the bike is capable of...
That would be my suggestion.


1) Not all but some do, for certain cases that data can be extrapolated. The information for Lateral G's of tires can also be calculated from skid pad tests and lean angles. And there is also data for that somewhere. You would only need to take a few samples to make a simple dropdown with "average" differences.
i.e. Michelin Pilot Power Tires - RevZilla
Assuming tested at the Michelin test track you can get presumably calculate the coefficient of friction as 1.2 dry and .90 wet (source).
Whether there is more data, I am not going to bother looking, but that's a good start, go up and down from there

2) No more than we can trust the bank angle and google maps corner points
3) See note above...

Whether you change up your site or not, I think it's a useful tool after knowing it's current limitations (fixed assumptions etc...). I appreciate your consideration of my suggestions, and if you find my feedback insightful enough to change your site, I would be greatful for your additional efforts.

Cheers,
~CYD
I'm confused. You do realize that if you bike is capable of 45 degree lean without sliding, it can do 45 degrees at 30mph and at 150mph right?

If you tire's coefficient of friction allows for 1G then all you can lean is 45 degrees regardless of speed. At 45 degree lean, you will always be doing 1 lateral G nomatter your speed.

So if I let you select 1G it's the same as letting you select 45 degree lean.
In fact, when you select 45 degree lean in my app, it shows that it equals 1G.

You are correct, if michalin says they can lean to 50.6 degrees, that means the tire can do 1.2 lateral G's.

so why have both coefficient of friction and lean angle as inputs by the user if they are directly related to one another. I think most people understand lean angle better than Meau.

PS - Steve from http://www.stevemunden.com/leanangle.html has already seen my app and really liked it. He didn't say anything about me missing any variables such as wheelbase, suspension geometry, tire grip etc.. I've been in contact with him since 2 months ago trying to understand motorcycle dynamics. At first I was like most of you. I refused to think that the weight of the bike has nothing to do with the lean angle for a given speed and turn radius. I always thought that lighter is better, so a lighter bike will have to lean less, or can take the corner sharper for a given lean angle and speed.

Last edited by noamkrief; 01-04-2013 at 01:56 AM.
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Old 01-04-2013, 03:31 AM   #85 (permalink)
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Originally Posted by noamkrief View Post
I'm confused.
me too.

PM sent.

Cheers,
~CYD
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Old 01-04-2013, 12:14 PM   #86 (permalink)
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What a waste of time. Want to know how fast you can push your bike through a turn? Go ride your bike through the turn to the best of your ability. How fast did you go? There's your answer.


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Old 01-04-2013, 01:11 PM   #87 (permalink)
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Quote:
Originally Posted by noamkrief View Post
Many people have contacted me saying that i'm missing variables of their bike.
What kind of tire?
Mass of the bike?
Wheelbase of the bike?

Those don't matter and here is why:

Any single track vehicle, motorcycle, bicycle etc will have the exact same lean angle per given radius and speed.

This concept is difficult for most to understand.
Lean angle is "the angle at which the force of gravity which is trying to pull you down is exactly offset by the centrifugal force being generated."

Represented by: lean angle = arctan(v^2/g*r)
v = velocity in m/s
g = 9.81 m/s^2
r = radius in meters

So, no. Mass of rider + bike, wheelbase, C.G. height has no effect on the relationship between radius, speed, and lean angle.

The easiest way I can explain this is the following:
When you travel in an airplane and the airplane turns, your cup of water is not spilling over. The water is perfectly level in the glass even though the plane is banking.

Now imagine a Cessna 172 flying at 140mph banking at 30 degrees
Now imagine a Boeing 747 flying at 140mph banking at 30 degrees

Will both fly the same radius arc? If you answered yes - you are right.

A Harley, a bicycle, and an s1000RR are all going into a 200 foot radius turn at 50mph.
THEY WILL ALL LEAN 39.95 DEGREES to negotiate that turn. Period.

And it doesn't matter that your S1000RR has full slicks. 39.95 degrees.
The slicks will offer you one thing. Extra available traction - for things like being to accelerate hard while leaning over far.
Someone remember his private pilot knowledge regarding the radius of turn and bank angle with regards to centrifugal force.

All forces are equal in a coordinated turn. Good example where u sre trying to apply this website. I like it, cant wait to test it out in the spring

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Old 01-04-2013, 01:30 PM   #88 (permalink)
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Default It's been a fun lesson

Cool innovative tool along with the physics crash course! I'm a math junky too. I followed along throughout the back and forth banter and must say that I would never use an app like that for street/spirited riding.

I couldn't rely on a piece of technology to judge my speeds in corners.
What if that corner is off-camber? Or a downhill corner? Wildlife around that bend? This is where skill and experience come into play. I don't care who you are, an exp 10 yr rider vs a 2 yr rider will have different skill sets.

IMO there's a certain "feel" to each corner. It's something learned thru many miles/years/riding/race course(s), etc. If an app can tell me I can go X speed I would NEVER LOOK at my speedo to confirm in a turn. I really never look at my speedo anyway. I know how fast I'm going by the feel of the bike, gear selection, and the sound of my RPMs. There's really no time to look at the speedo, too much other crap going on. You got traffic, traffic signs, wildlife, soil spots, oil, debris, snake strips, cracks, weather, water, SEMI trucks, the list is endless.

I really commend your efforts Noam. Just a word of caution to the newer riders "Skill and experience may vary, use at your own risk!"

Happy New Years everyone!
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Old 01-06-2013, 02:18 PM   #89 (permalink)
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Thanks for your work with this Noam. I think your app is going to be useful to me.

The most vehement opposition in this thread is probably because people think you are finding the MAX possible speed through a corner. Some posts attribute that to you explicitly. You are clearly doing no such thing. You are allowing a user to select a lean angle and solving for the speed through a given turn. This has NOTHING to do with the max possible speed through the turn. Max possible speed is what a physicist would call a boundary value problem, where there is a limiting factor somewhere (tire friction in this case). People are all wound up trying to invoke their specific boundary values, from poor suspension to absurdly long wheelbase. Yes, if you invoke an absurd boundary, Noam's solution will not be valid because he never set out to solve a boundary value problem. He is finding the solution to the lean angle equation, and a useful solution it is.

Thanks again, Noam.

- John
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Old 01-06-2013, 03:58 PM   #90 (permalink)
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Quote:
Originally Posted by Technomancer View Post
This has NOTHING to do with the max possible speed through the turn. ...
- John
I have noticed Noam has been more accepting as of late to take into consideration other pieces of the pie. And he has had a good discussion with CYD. I thought it was some very good discussion in fact.

But to go back to your statement John - above... it may likely be due to the title --> "sweet new website that tells you how fast you can ride for a given turn on the street " One could easily assume this to be max, since it's saying how fast you can go.... May be misleading in your opinion, eh?! I may be confused too, as I thought this was what he was after and has been discussing in the thread?!
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