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Old 01-05-2015, 10:08 PM   #121
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Quote:
Originally Posted by Sudo View Post
Except, is roll torque the limiting factor? No... That's why motorcycle LOWSIDE when pushing to the limit. And the only reason for highsiding is due to not enough lean, purely due to user error, not physical limitation.
The roll torque isn't the limiting factor but it has to stay in balance or your lean angle will change. The rolling over to the outside isn't a high side, it's simply flopping onto the other side, which will never happen because you can't produce more lateral acceleration without the equivalent lean angle.

You're right traction is the limiting factor but your traction will limit your lean angle. Marc Marquez can't go out on ice and hit 60 degrees. He doesn't have the grip. Lateral g's and lean angle are connected, end of a story. Given enough traction the lean angle through a turn at a certain speed will always be the same.

Also do you understand how highside a occur? It has nothing to do with this conversation or your lean angle.
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Old 01-05-2015, 10:11 PM   #122
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Quote:
Originally Posted by Sudo View Post
Except you miss the fact that it applies to 4 wheel vehicle as well. A car can be on 2 wheels, same physics applied. Limiting factor is traction. If I can dynamically eject 2 wheels off of a Formular1 car during a turn. I can garentee that you will lose traction before rollng and tipping over, unless you hit a curb LOL.
Two wheeled vehicles have completely different dynamics from four wheeled vehicles. When a truck rolls has it lost traction or could the width of the vehicle not over come the roll torque?
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Old 01-05-2015, 10:15 PM   #123
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Old 01-05-2015, 10:18 PM   #124
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Old 01-05-2015, 10:25 PM   #125
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The only disconnect here is that if you are at the limits of grip you cannot lean anymore. Lean angle does matter for lateral g's because they have to balance for you not to fall. Everyone here(except maybe kenup ) agrees traction is the limiting factor but also the bike with the most grip will also have the highest(or lowest?) lean angle.
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Old 01-05-2015, 10:30 PM   #126
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Old 01-06-2015, 05:05 PM   #127
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Demonstrated lean angle equals demonstrated cornering g's and therefore demonstrated grip. This easily surpasses 1 g for all sportbikes.

I cannot help it if that just bugs some people. It's really too bad, because there is a lot that can be learned otherwise.


The only reason cars came into this, is from the onset it was said, as is easily believable, that cars will pull more corner g's than a bike could and two examples were given of 1.08 or 1.12 g as somthing that bikes would not be able to surpass.

If we want to belive that then you would be very disapointed with the bikes performance and woukd probably not be into them if your thing is sport or track riding.
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Old 01-06-2015, 06:07 PM   #128
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Quote:
Originally Posted by brandontx View Post
At 2:25 he momentarily pulled 32 Gs. That's got to be a record.
His meter only reads to 1.5 G's.. and it occasionally spikes a little past.. where did you come up with 32?
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Old 01-06-2015, 07:12 PM   #129
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Quote:
Originally Posted by kenup283 View Post
Demonstrated lean angle equals demonstrated cornering g's and therefore demonstrated grip. This easily surpasses 1 g for all sportbikes.

I cannot help it if that just bugs some people. It's really too bad, because there is a lot that can be learned otherwise.


The only reason cars came into this, is from the onset it was said, as is easily believable, that cars will pull more corner g's than a bike could and two examples were given of 1.08 or 1.12 g as somthing that bikes would not be able to surpass.

If we want to belive that then you would be very disapointed with the bikes performance and woukd probably not be into them if your thing is sport or track riding.
What's your source?

And who said a bike can't exceed 1.12 g's. The video from my bike shows otherwise and it's nothing special.
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Old 01-06-2015, 08:23 PM   #130
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Also we proved a Miata did 2.2 g's which is a 65 degree lean angle that hasn't been done as far as I know.
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Old 01-06-2015, 09:33 PM   #131
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I don't get it, what I am reading Kenup to say is something completely different from what you 2 are responding to.
Unless I am way off base, he is saying cars were brought into the discussion because it was claimed they could pull more lateral G's than a bike.

He agrees with that assessment.

Then he is saying somebody claimed that bikes could not exceed 1.08 or 1.12 G's.

He is disputing that, and saying that bikes could go higher than that. He didn't say that bikes could make it to 2.2.
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Old 01-06-2015, 09:38 PM   #132
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Quote:
Originally Posted by kenup283 View Post
The benefit of doing the test would be to show people that cars run out of grip before bikes do.

You can see this from the very first posts here, people are too quick to say cars have four tires and they are wider therefore cars are going to pull more lateral g's. Sounds good expect for being completely wrong.
Here is where he clearly says bikes can pull more lateral g's than a bike.
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Old 01-06-2015, 10:03 PM   #133
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Quote:
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Here is where he clearly says bikes can pull more lateral g's than a bike.
Well, there ya go.
He's incorrect on that statement, lol
Guess I missed that.
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Old 01-06-2015, 10:11 PM   #134
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Old 01-06-2015, 10:23 PM   #135
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Because the max lean you can get on the bike is at the max lateral g's. Lean angle is more easily measured so kenup suggested as a better metric as opposed to lateral g's.
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Old 01-06-2015, 10:33 PM   #136
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Last edited by Sudo; 01-06-2015 at 10:36 PM.
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Old 01-06-2015, 10:44 PM   #137
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Quote:
Originally Posted by Sudo View Post
So measuring the lean angle of center mass is easier? Not quite. Especially center of mass is dynamic on a bike due to rider position. Accelerometer and gyro combine will be the best measuring tool. Again, seems redundant to me...

So what sensor do you use to measure center mass on a moving bike?
You measure the bike lean angle and assume the rider uses the same body position on each bike. I don't agree with this testing if you want to know max g's but it's what kenup suggested.

You could also calculate it by the forward velocity and radius.

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Old 01-06-2015, 10:50 PM   #138
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Old 01-07-2015, 12:21 AM   #139
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Old 01-07-2015, 06:01 PM   #140
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lol. We all know that Miata is a go kart with doors.

The idea was to say that generally speaking you're not going to out perform a bike in terms of max cornering g's with a car. That is a misconception widely held that I was trying to break down.

Average cornering g's, and comfort level in doing so, is another question but even still just depends on the type of corner and the rider of the bike. Yes it takes a much better rider to equal the average driver.


As far as measuring. What I said was cornering g's are easier to measure, but lean angle is easier to think about (at least I thought so anyway ).

It also gives us some boundaries to work with and to arrive at very close approximations to what the original poster was after.

Discussing grip alone will not get you to cornering g's.


My source for saying all sport bikes are capable of over 1 g. A reasonable assumption based on speeds carried around corners of a known radius at track that we have seen all types of bikes having been ridden. Here I was truly hoping for someone, cough... cough, maxgs, to front some data collected on many different riders on many different bikes.


All that said, these things are best discussed over some beers, so be warned that my wife just yelled at me for finishing the bottle of wine set out for this evening.



Have you ever heard someone say, you go fast in the fast corners and slow in the slow corners..... because that is where you make up the most time. Ever wondered why?

Keith Code discuses this in context of reaction times of riders inputs, which is true, but there is even more to it than that which can be shown with these concepts being discussed here.


Take the key hole and carousel at MSRH. 50 m and 120 m radius turns.

In the keyhole, at 40 deg lean (0.84 g) the speed would be 45 mph, and at 50 deg lean (1.2 g) the speed would be 54 mph. A difference of 9 mph.

In the carousel, at 40 deg lean the speed would be 70 mph, and at 50 deg lean (1.2 g) the speed 84 mph. A difference of 14 mph.

So for the same risk of using 1.2 lateral g (~600 lbs. times 1.2 of cornering force) a greater gain in cornering speed is achieved. The same risk does not come with the same reward in the slower corners, but is met with greater reward in the faster corners.


The concepts we have been discsuing all this time will show that the difference is proportional to the square root of the ratio of the radius of the corners.

In our example, sqrt ( 120 / 50 ) = 1.55

So the speed through the carousel is 1.55 times greater for the same amount of cornering force (grip) as used in the keyhole.

Likewise the time it takes to get around is 1.5 times quicker at 50 deg lean than 40 deg. That's huge.

You can back check this by taking, 45 mph times 1.55 and get 70 mph, or 54x1.55 and get 84.


I pulled these values out of the tables you can see in the pictures from prior posts, but I also made a plot below.


speedvsrad zps058c543a



You may be wondering why I choose to look at 63 deg and 60 deg. in the plot above as those numbers are totally irelavent to guys like us.


Well in MotoGP they included lean angle sensors in the TV graphics this year, and they show Mark Marquez going down to 63 deg. and at times when his teammate and others are doing 60 deg.


So what is a measly 3 deg, worth?


As said before, the increment is worth more at greater lean angles.

Here it would be the difference between 1.75 g and 2 g. That is a 13 % increase !!


Now if we ask what is the time gained?

Well it depends on how long he can do it for while the others are at 60 deg.

If we break it down in terms of arc length of a turn we can get the following.

dealtaspread zps5cd0c29b


If we look at the top line which represents a 45 deg arc segment where Marquez holds 63 deg lean and the other only do 60 deg. Then look at an 80 meter radius or 90 mph turn (we can get the speed from the plot above) then he picks up 0.10 seconds in just that one segment.!!

In reality its going to be less than a 45 deg arc in which he bests the others, but if say its one fourth that, and the track may have 4 turns like this, then its a tenth per lap that the 3 degs extra can net.

Crazy stuff.
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