n00b totals 250 on first ride

[Sinister]

Originally Posted by drac

Dudes....WTF r u people talking about..........I just stopped my 2009 ninja 250 from 28(32 on speedo)mph to a stop 9 times.....Averaged 14/15ft the first 6. The last three were 20, 17, 15.5......

And you guys are telling me that is impossible??????

It happened, it is a fact......deal with it

Will post the vid tonight if I can. Will try to get a better vid in the next couple days.

Sorry but you guys don't know what you are talking about.

You're an idiot who doesn't know when to be hush up and withdraw from a discussion. Your backyard tests mean absolutely nothing. The simple fact is that you cannot stop a bike, even a superbike, in as short of a distance as you can a car. Even a heavy car. Here is even more proof for you:


Here are 3 performance sedans. All weighing over 2 tons. The WORST of them stopping in 111 feet:
http://www.insideline.com/cadillac/c...gination_top_3

Now here's a test of some literbikes. The BEST they managed was 129 feet:
http://www.motorcycle-usa.com/268/98...omparison.aspx



And yes. I think its entirely possible to stop a 250 that fast. By hitting a tree. Hopefully we see a vid of that.

[etiainen]

Originally Posted by Sinister

You're an idiot who doesn't know when to be hush up and withdraw from a discussion. Your backyard tests mean absolutely nothing. The simple fact is that you cannot stop a bike, even a superbike, in as short of a distance as you can a car. Even a heavy car. Here is even more proof for you:


Here are 3 performance sedans. All weighing over 2 tons. The WORST of them stopping in 111 feet:
http://www.insideline.com/cadillac/c...gination_top_3

Now here's a test of some literbikes. The BEST they managed was 129 feet:
http://www.motorcycle-usa.com/268/98...omparison.aspx



And yes. I think its entirely possible to stop a 250 that fast. By hitting a tree. Hopefully we see a vid of that.

More weight but also four tires and more traction on the road.

Apparently impossible things are possible when people say so on da intarwebz.

[THE BIG SITT]

Joined the argument late, but I'm getting tired of an email from this thread every five minutes, so I'll go ahead and throw in my two cents.

As it turns out, my two cents is in the form of a link:
http://www.rcramer.com/bikes/ex250/specs.shtml

Check out the braking figures on the bottom right.

[THE BIG SITT]

And this:

http://faq.ninja250.org/wiki/Maximum_braking

[etiainen]

Those numbers are more consistent with reality and 0.8g deceleration rates.

[Captred]

Let me see if I have this straight. The majority of contention in this thread is coming from a single poster...telling any and all what's what with regards to braking and in a rather condescending manner towards the OP, all in the name of riding safely. This same guy started another thread with regards to AGATT in which he complains about others whom he implies have a condescending attitude towards those who choose less gear, himself included.

Ironic or moronic?

http://www.ninjette.org/forums/showthread.php?t=105261

[Jiggles]

^ Trolonic?

[drac]

I can hear it now.... Well we cant see the speedo...Well we cant see the bottle in second stop.......blah blah blah....

Hears the deal....

When I got to the bottle I was at 31/32 on speedo. You'll have to trust I am telling the truth or you can send me videocams like Jigs has and you can see it all. I assure you I was at 31/32 on the speedo

In the first stop notice the bottle is lined up with the electric fence post with the white paint at the top. It's for a cow pasture... Hey, I told you I lived in the country.... The bottle is in the exact same spot for the second stop.

I watched this using VLC player(free) slowed down to 1/4 speed. It gives you a great view of how compressed the front suspension is along with the ability to really hear the tires squealing. Mostly you hear the front tire squealing because I don't lock the back up untill just before total stop.

If you doubt the authenticity of this video I can't help you. All I can say is send me all the video equipment I need to satisfy whatever view you want to see and I will gladly make videos and send equipment back. If you aren't willing to send the equipment then this is the best I can do. I will try to get up a video that shows things a little better.

I think in on the second stop I might have braked a little early. I hear tire squeal real early on and I didn't think I locked up the back until late in the braking maneuver. So I can only assume it is the front tire unless I jumped on the back brake a little harder than I wanted too and locked it up for a second.

Sorry... but taking 30+ feet to stop a 250 ninja from 28mph is downright laughable.


http://www.youtube.com/watch?v=V8riJ...ature=youtu.be

[Jiggles]

^ thats a terrible scam! NOBODY SEND HIM CAMERAS!!! LOL

[Jiggles]

We said 28mph not 28 kph!

[THE BIG SITT]

Then it is solved. You're bike is the bestest ever.

/thread

[drac]

Originally Posted by THE BIG SITT

Then it is solved. You're bike is the bestest ever.

/thread

No just an average 2009 ninja 250......Anyone can learn to brake that hard but it takes a lot of practice.

[Jiggles]

/need unobtanium brake pads

[Jiggles]

Oh wait guys I know why he is stopping so fast. Rear brake all makes sense now

[Sinister]

Wow. What a useful video. I am SO willing to take your word for... whatever the hell that was... over all the information posted here from sources that have the equipment to actually perform measured tests and report unbiased results from said tests.


Now go away.

[Motofool]

The math of this braking distance discussion is very simple, for those more numerically inclined.

If we want to calculate the minimum distance possible, we need to assume the maximum achievable deceleration (1g).

The formula to use is the one for free fall: S = V^2 /(2g)

Let's calculate the distance that it takes to any physical body to free fall from repose down to the point at which it reaches 28 mph or 41 feet/second:

S braking = (41)^2 /(2*32.2) = 26.1 feet

If Sean did not slow down at all before impact, his body felt the force of falling (him and bike) sideways from that height.

Using the time and reaction numbers of my previous post, let's calculate the distance that he covered in the time from recognition of danger and reaction (0.7 seconds) to reaching maximum deceleration (0.3 seconds).

S reaction = V * t = (41 feet/second) * (0.7 + 0.3) = 41 feet

Hence,

S total = S reaction + S brake = 41 + 26.1 = 67.1 feet


Now, you can play with those formulas and numbers and reduce the reaction time at will or reduce the deceleration rate.

For example for half that reaction time (very hard to achieve) and a less than optimal deceleration of 0.8 g:

S reaction = (V * t/2) = (41 feet/second) * [(0.7 + 0.3)/2] = 20.5 feet

S braking = (41)^2 /(2*32.2*0.8) = 32.6 feet

S total = S reaction + S brake = 20.5 + 32.6 = 53.1 feet


I hope that the importance of reducing the reaction time can be understood from this example.

[gilmorec61]

This makes me wonder how long i was on asphault, and what they did to me...

[Jay72]

Originally Posted by xSean13

Lol, free health care. Then he'd be waiting a month for them to do anything, and any physical therapy would take ages.

Pretty silly comment since you don't even live in Canada, how the hell do you know? You really think he would wait for any of that to be taken care of or for physio to start as soon as he was able to do it? Come on man you are talking out of your ass. Came across this little tidbit give it a read.

http://www.reuters.com/article/2010/...65M0SU20100623

[dfox]

Originally Posted by Motofool

If we want to calculate the minimum distance possible, we need to assume the maximum achievable deceleration (1g).

I haven't even started to look at the calcs, because...

where did you come up with 1g? did you do calculations for the ninjette, the exact amount of gasoline in the tank, and the exact rider body position and weight? the maximum deceleration rate depends on either the coefficient of friction between the tire and the road (locking up the front), or the motorcycle and rider's center of gravity. Get your center of gravity back and low, and you can achieve a greater deceleration rate. It's all in the geometry and rider positioning.

and for anyone who argues against a rear brake, THIS is what you need to look at, not just a general blanket statement that sport bikes will "stoppie" before you lose traction. The geometry matters, as does the rider position. It may be possible that if you get low enough, push your weight back hard enough, that the rear brake DOES still have weight on it in an emergency stop.

[Jiggles]

^. Guys, rear brake is feasible, just get low, duh

[Ptdoughnut]

just gotta have some junk in the trunk....

[Jono]

Originally Posted by Jiggles

^. Guys, rear brake is feasible, just get low, duh

If you followed/practiced these tips... http://www.sportrider.com/ride/146_9...ops/index.html You wouldn't have had such a bad crash.

What you did wrong...

1.

The quickest way to stop is by using a combination of both front and rear brakes. The front brake should be applied gradually, rather than grabbed suddenly. This will decrease the chance of it locking up. The rear brake should be used firmly, to the point of impending lock up. Both tires will howl on the verge of lock up, and that's when the quickest stops are made. Find an empty parking lot and practice different scenarios including bumps, while turning, and in the rain.

2.

While riding, you should be scanning the road ahead, looking for anything that may cross your path unexpectedly. Note the characteristics of the surface you're riding on and be ready to use the brakes accordingly. Keep one or two fingers on the front brake lever and your foot over the rear brake pedal. If you can't see the road ahead for the distance you'll need to stop at the speed you're traveling, slow down.

3.

When you must brake, don't panic and grab everything you can.

Or in your case don't throw your right foot forward in hopes of kicking the car out of your way. That foot should be on the rear brake pedal.


If you could just get your head out of your ass you would clearly see that you made some mistakes and the crash was avoidable.


Would I have made the same mistakes as you? It's possible, but I hope I would do a little better in that situation. I am young and inexperienced like yourself. Learn from your mistakes.

[Jiggles]

Originally Posted by Jono

If you followed/practiced these tips... http://www.sportrider.com/ride/146_9...ops/index.html You wouldn't have had such a bad crash.

What you did wrong...

1.

2.

3. Or in your case don't throw your right foot forward in hopes of kicking the car out of your way. That foot should be on the rear brake pedal.


If you could just get your head out of your ass you would clearly see that you made some mistakes and the crash was avoidable.


Would I have made the same mistakes as you? It's possible, but I hope I would do a little better in that situation. I am young and inexperienced like yourself. Learn from your mistakes.

May I direct u to the rear brake thread so you can see you are wrong?

[Jono]

@Jiggles Yes, Please.

[rmorse]

Jiggles, maybe you should find someone like this dude in your area:

http://smd.craigslist.org/mcy/3074876709.html

[Jiggles]

^ dumb

[Jiggles]

Originally Posted by Jono

@Jiggles Yes, Please.

http://www.ninjette.org/forums/showthread.php?t=21607

GLHF

[rmorse]

Originally Posted by Jiggles

^ dumb

Awww.

[Jiggles]

[dfox]

Originally Posted by Jiggles

^. Guys, rear brake is feasible, just get low, duh

i refuse to argue with anyone about the front/rear brake issue.

it is a fact though, that tires, rider position, rider weight, and wheel base play into whether or not to use a rear brake on your bike in an emergency. It's purely geometry/physics, and can be calculated.

a generic statement of 1g is the maximum breaking force until you lift a rear wheel, is not correct.

[Alex]

That's true, that 1g is not necessarily the maximum braking force due to any rule or constant. Vehicles can theoretically brake harder and stop faster. But practically, with rubber tires and pavement, it's a pretty good approximation of the best you can do.

A 1g stop from 60 mph takes 120 feet. The best street vehicles in the world are in the 110 feet range, and the worst you'd ever want to drive would be in the 140 feet range. Motorcycles aren't far off of those numbers either. They are lighter, which helps to some extent, but they have smaller contact patches, which hurts to some extent.

Now with race tires on a vehicle with ground effects, these numbers ramp up quickly (think F1).

[Motofool]

Originally Posted by dfox

...........where did you come up with 1g?

From Twist of the Wrist II and from the links shown in posts #138 and #284 of this thread.

What is your favorite number for g?

"Perhaps it is difficult to sort-out the difference between the higher (around 1.0 G maximum) load of the braking and cornering forces from the much less pronounced acceleration (.1 to .2 G) required for optimum traction/suspension........

The average braking distance hasn't changed much in the past 15 years! For streetbikes or racebikes, once the back wheel is off the ground, with 100 percent of the bike's weight being carried by the front wheel, that's the end of the game where braking is concerned: You've run up against the laws of physics. Racers have been able to get the back wheel up, under braking, for two decades!......

The obvious mathematics of the situation are that the front wheel can do 100 percent of the braking and the back at that point just locks up no matter who you are. Learn to totally rely on the front brake for quick, clean stopping......."

[dfox]

So a rule of thumb?

What your quoting is a generic statement. The reality is that every bike is different, and what holds true for a cbr600rr won't hold true for the ninjette.

I have no brake force, it would need to be carefully calculated out,and I do enough calculations every day to bother with this.

Edit "obvious mathematics" ignores the dynamic affect that applying braking forces at two different locations imparts. The rear wheel will cause the bike to dive, but not flip. I would argue, that when properly applied, using a rear brake will reduce brake distance, but completely agree with the opinions that in an emergency, a rider cannot possibly control both brakes properly.

[Jono]

Originally Posted by Jiggles

http://www.ninjette.org/forums/showthread.php?t=21607

GLHF

All I read was a bunch of opinions.

I do agree that the rear brake should be avoided at high speeds anything above 60mph but at the speed you were going in your crash below 30mph. I think the rear brake would definitely help you stop quicker. If you don't lock it up that is.

Just another opinion. I did go practice hard braking in a parking lot today and found the rear brake to be helpful. I will need to go back and do some measuring to see if it really is beneficial like I believe it is. But it is hot as balls and I am lazy. Maybe if it ever cools down I'll test out my theory.

[Motofool]

Originally Posted by dfox

So a rule of thumb?

What your quoting is a generic statement. The reality is that every bike is different, and what holds true for a cbr600rr won't hold true for the ninjette.............

Todays' motorcycle tires allow lean angles of 45 degree.

Well, that means that these tires can support 1 g at that angle.
Tires used in GP can withstand higher g's, almost up to 2.

What all this g business means?
These tires generate a gripping force that can equal (g=1) or surpass (g>1) the value of the weight that they support.

If that is true, then a front tire commanded to stop rolling by strong enough calipers, can generate a decelerating (gripping) force equal to the weight (vertical force) that it supports during braking (hence, the more loaded the tire becomes the better).

Once the rear wheel is floating, all the weight of bike and rider is supported solely by that braking front wheel.

Let's say the Ninjette and the rider weight 500 lb, then you can achieve a decelerating force of 500 lb (which is equivalent to the free fall of my previous calculation).

Up to this point we have only considered achievable friction force, which applies to any bike (hence, the book is correct).

As you have correctly explained, the geometry and location of the CG of the bike-rider will determine if the bike flips much (performing a stoppie) or none.

A cruiser is long and much heavier than the rider; hence, the combined CG is low. Even if it can brake at 1 g of deceleration, the moment that tends to keep the rear wheel planted wins over the flipping moment. In this case the rear wheel does not float and still carries some of the total weight; therefore, it has some braking power to be used.

A sport bike is short and not much heavier than the rider; hence, the combined CG is high (about half the distance between tire patches). Anything above 1 g of deceleration will make the flipping moment grow above the moment created by the weight applied to the CG, inducing a stoppie.

[drac]

OK Motofool....I weight 147lbs.... How fast can I stop my ninja from 30mph?


Whether you choose to believe the video I post or not I am telling you in no uncertain terms that I stopped my bike consistently in 17 feet or less from just over 30mph on the seedo

Just curious what your math says and do you stand by whatever number you get from said math?


I live alone but the next time someone is over I will do another braking vid stopping from 30mph then 40mph.

[dfox]

@Motofool

sigh... we're saying the same exact thing, except the numbers you're using do not take into account the dynamic aspect of braking. in pure statics, you are correct, the maximum braking force would be equal to the weight of the bike and rider because (f=mu*mg), and that's assuming a 1.0 coefficient of friction. The dynamic affect of braking and the change in momentum will impart additional forces to the front tire, increasing the achievable braking force.

Due to the dynamic loading affect, and varying center of gravity between every different bike and rider combination, nobody can generalize and say that 1g is all you can achieve. Some sport bikes might be at 1g, others might be below it, and others might be above it. My sense (without calculation) is that most will be at or above.

[Countersteer]

I agree with everyone. Everyone is right.

[Jiggles]

^ dis guy haz smart

[Motofool]

Originally Posted by drac

OK Motofool....I weight 147lbs.... How fast can I stop my ninja from 30mph?

Whether you choose to believe the video I post or not I am telling you in no uncertain terms that I stopped my bike consistently in 17 feet or less from just over 30mph on the seedo

Just curious what your math says and do you stand by whatever number you get from said math?

I live alone but the next time someone is over I will do another braking vid stopping from 30mph then 40mph.

I have no reason not to believe you or anybody else.

If you were really starting the braking at indicated 30 mph, which is not obvious in your short video, you were decelerating at a rate of 1.53 times the acceleration of gravity (g), in order to come to a complete stop in 17 feet.

Next time, try a stopple in the same conditions for us to see if the distance can be reduced even more: I believe you could do better by making the rear tire float.

I stand by my math; however, I have been wrong before.

What I am trying to confirm with these and previous calculations is that the OP couldn't avoid this specific collision against that car via the best reaction and braking he (or anybody else) could do with his Ninjette.