What's going to happen?

[Cayman911]

I've heard the 250 Ninjas have craphouse factory tires. That might also have contributed.

So have i, and it is repeatedly mentioned in most the reviews you can find too.

apparently they are too hard and beginners might find em a handfull

[R-Soul]

That doesn't mean it's making more power than a big bike, it means the engine is working harder. The connection between the rear tyre and the road isn't affected by how hard the engine is working.

A 250cc in 6th gear will not have enough torque to cause teh wheel to break traction (even on tar bleed) unless the surface is VERY slippery. Like someone said- diesel (on paint).

[R-Soul]

The revs relate to the torque in that their product is the power. This means that if you had a perfectly flat, horizonstal torque curve (a torque "line" instead) then the power curve would also be a straight line from idle up to the rev limiter.

Velocity is the rate of change of position, dunno where you were going with that "etc...".



Why? More torque to the rear tyre means the rear tyre would spin more. The traction/friction that exists between a your tyre and the road will be the same regardless of whether your engine is 50cc or 5000cc. The traction will be overcome by a certain amount of power. The tyre-road connection doesn't know where the power is coming from or how fast your engine is revving.

At 9000rpm you had about 22hp going through your back wheel. The same as a ZX10 makes at about 2500rpm. Alright, a ZX10 also has more grip due to being heavier, bigger tyre and such but if the tyre-road connection were the same (and it's not far off) then it would have the same chance of breaking traction on any bit of road at 2500rpm as your bike does at 9000rpm.

Ninja 250 power curve

ZX10R power curve

Actually you would be looking atthe torque figures rather than the hp figures, since that is what is going to cause you to break traction. At almost idle, the ZX10 has about 50Nm, going up to about 100 Nm + maximum at high revs.

[For the benefit of Mudfart: This is because it has a large bastard of an explosion going on in each cylinder, and acting on a large surface area (the cylinder's cross section), making it give a big push. Large pressure acting on large area= large force. That large force is translated (by the transmission) from linear movement by the piston to rotational (also called angular) movement , acting backwards at the traction band on the road.

It is the torque figures for bikes /cars that give you an indication of their acceleration (0-100 times). Actually its more the torque to weight ratios.

Power is (mathematically) torque multiplied by angular or rotational velocity. Power is the ability of an engine to maintain high torque to high revs. A problem occurs at high revs in engines because the airflow becomes the bottleneck -you cannot get enough air into - and out of- the engine fast enough to burn with the fuel. So power is actually more of an indication of that engines ability to breathe. And more indicative of the top end speed of the bike as opposed to acceleration.

This is why engines with a small number of cylinders (eg V-twins) have high torque and low power - large capacity cylinders cause high torque, while only two cylinders create large airflow bottlenecks it high revs. And inline fours generally have lower torque but a higher capacity for breathing through four sets of valves and hence high power. And this is why the Triumph Speed Triple has a good combo of torque /power.


Note: sometimes the ignition sequence of a four cylinder can be used to make an inline four behave a bit like a V-twin, with two power pulses acting at the same time or close to each other to give good torque - like the 21010 R1]

The maximum torque for a 250cc is shown at about 12Nm. About a quarter that of the ZX10 at idle. And in 6th gear, the torque is nullified even further by long gearing. Thats why I am surprised it broke away - unless you went over a bump and got a bit airborne, reducing the traction enough to allow it to break away.

[Cayman911]

The maximum torque for a 250cc is shown at about 12Nm. About a quarter that of the ZX10 at idle. And in 6th gear, the torque is nullified even further by long gearing. Thats why I am surprised it broke away - unless you went over a bump and got a bit airborne, reducing the traction enough to allow it to break away.

gotta love the good old ninja 250's with the 24.00 Nm .

[avgas]

Oh lord. What a bunch of noobs.
I will speak slowly now.......
LEARN TO SLIDE
once you do that it doesn't matter what bike you like - you know how to recover from a slide. Where its on a pedal bandit or 100+Nm 100+kw monster.
I used to love kicking the back out of the old FZ1 (much to carvers fearful looks that I was gonna drop her)..........was the best bike for it. But at 100+kph it got a little scary.
Now I prefer the rear solid as a rock - sliding everywhere.
YEEHAA

[george formby]

I see no reason why you the back would not spin up if you hit something slippy enough. Suffered the exact same thing in Europe where their are HUGE patches of tar seal. In the rain riding sedately at 100kmh at low revs, the bike would spin up on every single bit of tar, some stretches would be close to 70mtrs long & the width of the lane. Only really noticeable by the revs shooting up. No drama's though & kept me very focused.

[Mudfart]

im figuring that you can trust the machinery to do the work, and come out of it still upright. otherwise we would all be in the shit.

[Scorp]

[For the benefit of Mudfart: This is because it has a large bastard of an explosion going on in each cylinder, and acting on a large surface area (the cylinder's cross section), making it give a big push. Lagre pressure acting on large area= large force. That large force is translated from linear movement by teh piston to rotational movement -acting sideways at the traction band on the road. It is the torque figures for bikes that give you an indication of their acceleration. Power is mathmatically torque multiplied by angular velocity. it is teh ability of an angine t maintain high torque to high revs. A problem occurs at high revs in engines because the auirflow becomes the bottleneck -you cannot get enough air into - and out of- the engine fast enough to burn with the fuel. So power is actually more of an indication of that engines ability to breathe. And moreindicative of the top end speed of the bike as opposed to acceleration

For the benefit of me too. Thanks for a great explanation of what torque actually is.

The maximum torque for a 250cc is shown at about 12Nm. About a quarter that of the ZX10 at idle. And in 6th gear, the torque is nullified even further by long gearing. Thats why I am surprised it broke away - unless you went over a bump and got a bit airborne, reducing the traction enough to allow it to break away.

Hypothetically, if the rider was 'trying' to induce the slide, as a result of a "wonder what'll happen if I do this" moment of madness, could he get the result Mudfart did?

[R-Soul]

For the benefit of me too. Thanks for a great explanation of what torque actually is.

Thanks man - just passing on what my lecturers told me in uni. Albeit with crappy typing...

Hypothetically, if the rider was 'trying' to induce the slide, as a result of a "wonder what'll happen if I do this" moment of madness, could he get the result Mudfart did?

Rriders can do stuff to increase the effective force acting against the traction by lowering the gearing - which is why its easier to break traction in first than 6th.

Or the rider can reduce the traction at the wheel. Traction or friction force is the product of weight and a friction factor (F =W x mu) attributable to the nature of the surface. (Strangely enough, in applied mathematics theory, the size of the tyre has nothing to do with traction. However, in practice, micro effects of the tyre "bonding" to and engaging with more microscpically small formations on the road cause the bigger tyres to offer better traction. )

By reducing the weight on the tyre, the traction can be reduced. Like by going over a bump. This is why braking on the back wheel is largely ineffective when braking heavily - because all the weight moves forward onto the front wheel. The maximum traction on teh back wheel is reduced, and it will start sliding pretty easily when you brake on it because the traction is pretty low.

Traction can also be reduced by having a different friction factor (eg. caused by diesel) , so that the same effective torque at the back wheel overcomes the traction and causes the wheel to break away .

Going with the microscopic effects of bonding and engaging by sticky tires, traction can be reduced by having cold tyres.

[avgas]

im figuring that you can trust the machinery to do the work, and come out of it still upright. otherwise we would all be in the shit.

You should have that kind of faith in the machine - otherwise what happens when it rains. Do you leave the bike at home.
OOHHHH NOESSSS THE WATER HAS DECREASE MY TRaction by 5%.....

[R-Soul]

You should have that kind of faith in the machine - otherwise what happens when it rains. Do you leave the bike at home.
OOHHHH NOESSSS THE WATER HAS DECREASE MY TRaction by 5%.....

I dunno about you , but I subdue my driving by about 50% when it rains fo rexactly that reason.

[R-Soul]

You wanted to know what other hairy situations you can find yourself in. Check out my thread:

http://www.kiwibiker.co.nz/forums/sh...post1129681211

Hope it helps.

[Lurch]

OOHHHH NOESSSS THE WATER HAS DECREASE MY TRaction by 5%.....

This man has never ridden a sub 250 in the rain before.

And seriously if you were cresting a hill at 120kph in fresh rain on a learner bike your fucken asking for it.

[R-Soul]

This man has never ridden a sub 250 in the rain before.

And seriously if you were cresting a hill at 120kph in fresh rain on a learner bike your fucken asking for it.

And seriously how do you expect any responses making any sense if you have an avatar like that!? I have come out of my daze and found an entire afternoon missing!

[Lurch]

And seriously how do you expect any responses making any sense if you have an avatar like that!? I have come out of my daze and found an entire afternoon missing!

huh? did you say something?

Actually i find it funny I have about 7 +vely repped posts almost exclusively due to my Avatar