Motorway Speed

unkel

Armin_Tamzarian wrote: »

260KPH or so.
It's funny how when you slow down from that speed to say 180KPH if feels like you're crawling.

I found that too! I used to start a very long (continental) journey at a high speed (not that the vehicles I drove were capable of anywhere near 260km/h though ) and then slow down but rather than relaxing while slowing down, still keeping 100% concentration on driving. It always felt right and safe and focussed.

rocky

220 in an 220CDI E Class
165 in a Panda

both in Germany

175 indicated in a rental Astra 1.4 in Ireland.

burger1979

Stinicker wrote: »

Driving at high speed is a little different for the driver due to the savage concentration required and different ways. Letting a massive gap between you and the car infront is obvious to allow for the long braking distances to slow down to even normal speeds never mind having to stop. Mirrors mirrors are so important as is proper lane discipline.

The germans are proper drivers and respect each other and generally know how to drive properly on the Autobahn at highspeed there can be no half measures as any tiny mistake has the potential to end your life (and many more) in the bat of an eyelid.

They know this and appreciate it and as result are actually better drivers. I would feel safer pusing 200km/h on the German Autobahn that having to deal with the morons who drive on our Motorways.

yeah alot of driving at high speeds has to do with driver training, the construction of the road and up keep of them too to a high degree of standard. tbh i find it difficult driving at high speeds for long periods of time on our own roads. i will admit that i have driven for 140-160kmh's for periods of up to half an hour and and the end of it all i feel quite tired. the mental thinking to be done to try and anticipate other drivers movements, the looking ahead to follow the road not 100-200mts ahead but at close to 400mts ahead. ( i will admit that it was stupid driving at these speeds, it was dusk time and on a fairly empty section of the M7).

all that said though if i got the chance, the proper car and the time in Germany to do it then i would love to go hammer and tongs on the 'ottobawn'. i would even do it if it was driver training with a company that specialised in that sort of thing and would hopefully improve my driving skills. in Germany whats the procedure for teaching drivers to drive on the autobahn? (slightly off topic but would be interested to find out).

corktina

MagicMarker wrote: »

Grand so.

well all the rest of youse are lying anyway. what a ridiculous thread....although the KFC did sound a bit more realistic.:D

KamiKazi

Regurlarly hit 180km/h on motorways, don't see the problem when there's feck all traffic around and the weather conditions are good. Bikes also generally have better braking power than cars.

Wossack

KamiKazi wrote: »

Regurlarly hit 180km/h on motorways, don't see the problem when there's feck all traffic around and the weather conditions are good. Bikes also generally have better braking power than cars.

incorrect there with regards braking..!

Mr.David

KamiKazi wrote: »

Bikes also generally have better braking power than cars.

In what way?

Obviously depends on the bike & car etc, but in general terms what makes you think so?

munchkin_utd

burger1979 wrote: »

<snip> in Germany whats the procedure for teaching drivers to drive on the autobahn? (slightly off topic but would be interested to find out).

Firstly, you have 12 compulsorary one and a half hour theory lessons so you know what is what. Very high focus on safety and following the rules in every aspect you can imagine.

On the road you are ONLY ever allowed drive
a)with a qualified driving instructor
b) in a dual control car.
No provisional licence exists so that non qualified amateur experts can teach you their tricks.

Anyhow, Motorway wise, you must do FIVE hours motorway training some of it also at night. You are only brought on the motorway though after you are a half ways decent confident driver and have taken lots of lessons in the city.
In the motorway part of the lessons, you practice and get used to things like
- how to blast on to the motorway using the acceleration lane (which in germany is quite damn short),
- how to come off the motorway correctly and slow right down (to 60kmh in third as i learnt!) in the deceleration lane ready for the normally quite curvy sliproad,
- merging between motorways (when 2 lanes becomes 5 say and you're in the middle suddenly),
- how to do a u turn using junctions and just generally how to keep your distance and drive safely.
- Oh and its also beat into you NOT TO STAY IN THE OVERTAKING LANE for longer than is necessary.

But generally, after 5 hours on a motorway with a qualified driver to answer your questions and give you professional guidance, you are quite well prepared to be confident of dealing with most things a motorway throws at you.

Anyhow, back to the OP question of speed, during my first motorway driving lession I was happily doing 160 down the ring road round Munich and not a squeak from the instructor. Something that might land me in jail in Ireland.
Crazy world.

KamiKazi

Wossack wrote: »

incorrect there with regards braking..!

You think so? On a clean dry motorway I'd take my chances on a bike TBH

Mr.David wrote: »

In what way?

Obviously depends on the bike & car etc, but in general terms what makes you think so?

Obviously they are lighter, and when you look at most bikes they usually have dual 300mm or so brake discs. Unless the car in question has upgraded / sportier brakes, I'd prefer to be on the bike

Mr.David

KamiKazi wrote: »

Obviously they are lighter, and when you look at most bikes they usually have dual 300mm or so brake discs. Unless the car in question has upgraded / sportier brakes, I'd prefer to be on the bike

Yes, they are lighter but thats irrelevant!


Firstly I'm not disagreeing that a bike could stop quicker than an average car - to be honest I really dont know, its your reasoning that I'm questioning.

Mass of the vehicle does not matter (so long as the brakes are sufficiently spec'd of course!)

When a vehicle is braking, the force is equal to mass x accleration (in this case deceleration).

F=ma

The force is present between the tyres and the contact surface i.e. the road and is a function of the traction (frictional force). The eq is:

F= uN (F is the frictional force/traction, u is the coefficient of friction between the two surfaces and N is the normal force/weight of the vehicle).

N, the weight/normal force is given by mass x gravitational force. If you substitute this in for N in the above eq you get:

F=uN=umg

We know F=ma, so substituting for F gives:

ma=umg

Cancelling the 'm' gives:

a=ug

So 'a' the deceleration of the vehicle is given by the friction coefficient and gravity.

In conclusion, the mass of the vehicle is irrelevant!

keithclancy

munchkin_utd wrote: »

Firstly, you have 12 compulsorary one and a half hour theory lessons so you know what is what. Very high focus on safety and following the rules in every aspect you can imagine.

On the road you are ONLY ever allowed drive
a)with a qualified driving instructor
b) in a dual control car.
No provisional licence exists so that non qualified amateur experts can teach you their tricks.

Anyhow, Motorway wise, you must do FIVE hours motorway training some of it also at night. You are only brought on the motorway though after you are a half ways decent confident driver and have taken lots of lessons in the city.
In the motorway part of the lessons, you practice and get used to things like
- how to blast on to the motorway using the acceleration lane (which in germany is quite damn short),
- how to come off the motorway correctly and slow right down (to 60kmh in third as i learnt!) in the deceleration lane ready for the normally quite curvy sliproad,
- merging between motorways (when 2 lanes becomes 5 say and you're in the middle suddenly),
- how to do a u turn using junctions and just generally how to keep your distance and drive safely.
- Oh and its also beat into you NOT TO STAY IN THE OVERTAKING LANE for longer than is necessary.

But generally, after 5 hours on a motorway with a qualified driver to answer your questions and give you professional guidance, you are quite well prepared to be confident of dealing with most things a motorway throws at you.

Anyhow, back to the OP question of speed, during my first motorway driving lession I was happily doing 160 down the ring road round Munich and not a squeak from the instructor. Something that might land me in jail in Ireland.
Crazy world.

And you forgot the cost .. its about 3000 euros in total for your Driving License ...

Here in the Netherlands its about 2400 euros.

By dual controls you mean the instructor has a clutch and a brake, which is also what they have in Ireland

The Germans aren't better drivers imo, they do their lessons and then after that all the rules go out the window.

I've been:
Cut off multiple times switching lanes on an slip road even though i'm coming from the right.
Sat behind a line of 4 - 5 cars doing 120 - 130 km/h in the Left lane while im there like a plonker in the right, a German or a Dutchman will just plough down the right lane past all of them.
Had a Micra pull between two trucks doing about 50 km/h
This week i saw a Girl on Wuppertal plates multiple times, driving fast, then slow, then weaving all over the place. 1st time she was fixing her makeup with the vanity mirror, second time she was on the phone, third time she was texting someone and the forth time she was looking in her bag for something, all this on unrestricted autobahn .. feckin nutter.

People from the south are always taking the pi*s out of people from the north for being total muppets in snow.

And thats just the ones I can remember. One big difference between Germany and Ireland is that Pedestrians are second class citizens, someone walks out on the road they'll keep going !

Autobahn isn't all that great either, alot of the unrestricted ones I drive on are no better than the M8 in Ireland !

Also if it rains it brings the whole feck*n thing to a standtill ..you may as well park and have a coffee.

On tuesday I got stuck behind a Cop car, retard wouldn't pull in and when he did I past him doing about 180 and not even a blink.

pajo1981

Mr.David wrote: »

Yes, they are lighter but thats irrelevant!


Firstly I'm not disagreeing that a bike could stop quicker than an average car - to be honest I really dont know, its your reasoning that I'm questioning.

Mass of the vehicle does not matter (so long as the brakes are sufficiently spec'd of course!)

When a vehicle is braking, the force is equal to mass x accleration (in this case deceleration).

F=ma

The force is present between the tyres and the contact surface i.e. the road and is a function of the traction (frictional force). The eq is:

F= uN (F is the frictional force/traction, u is the coefficient of friction between the two surfaces and N is the normal force/weight of the vehicle).

N, the weight/normal force is given by mass x gravitational force. If you substitute this in for N in the above eq you get:

F=uN=umg

We know F=ma, so substituting for F gives:

ma=umg

Cancelling the 'm' gives:

a=ug

So 'a' the deceleration of the vehicle is given by the friction coefficient and gravity.

In conclusion, the mass of the vehicle is irrelevant!

The 'a' in your last equation is MAXIMUM deceleration, which as you point out is independent of mass and only proportional to your tires friction coefficient.

The force required to stop a vehicle IS proportional to its mass, and this is why heavier vehicles have bigger breaks.

ed: Just read back a bit...

If a bike and a trucks breaks were sufficiently powerful (the trucks breaks would need to provide much more anti-torque) to take advantage of the max breaking traction afforded by the tires and the bike and truck had the same amount of the same tire in contact with the road, then in theory, yes, they would both stop at exactly the same rate. The reality is that a bikes breaking system is going to come closer to that ideal and the bike will break more quickly.

If you don't believe that objects with more mass are harder to stop: compare walking in front of a free-wheeling push-bike to walking in front of a free-wheeling train!

ed: apologies. I see we are making the same point!

Wossack

KamiKazi wrote: »

You think so? On a clean dry motorway I'd take my chances on a bike TBH

abs and bigger contact patch would put the average car driver ahead of the average biker in stopping distances I'd say

Mr.David

Wossack wrote: »

abs and bigger contact patch would put the average car driver ahead of the average biker in stopping distances I'd say

Excellent, you've fallen into my trap

F=uN where F is the frictional force, u is coeff of friction and N is weight.

So, the frictional force only depends on the friction between the two objects (tyre and road) and the normal force (vehicle weight).

Contact area does not increase friction!!!

So, if you take two tyres with exactly the same rubber compound - one a 195 width and the second a 295 width, they will both generate have the same max frictional force as u and N are the same!

This blows the common misplaced belief that the reason sports cars have wider tyres is that it generates more traction out of the water!

The explanation is a bit more complex - there is a reason though!

pajo1981

Mr.David wrote: »

Excellent, you've fallen into my trap

F=uN where F is the frictional force, u is coeff of friction and N is weight.

So, the frictional force only depends on the friction between the two objects (tyre and road) and the normal force (vehicle weight).

Contact area does not increase friction!!!

So, if you take two tyres with exactly the same rubber compound - one a 195 width and the second a 295 width, they will both generate have the same max frictional force as u and N are the same!

This blows the common misplaced belief that the reason sports cars have wider tyres is that it generates more traction out of the water!

The explanation is a bit more complex - there is a reason though!

Interesting. Although there is more rubber in contact with the road, the weight of the vehicle is spread over a greater area, and so, there is no increase in traction.

Mr.David

pajo1981 wrote: »

Interesting. Although there is more rubber in contact with the road, the weight of the vehicle is spread over a greater area, and so, there is no increase in traction.

Pretty much. On a high level there is more contact area, but on a microscopic level there isnt a higher contact area due to the reduced load (which pushes less of the microscopic level surface in contact).

KamiKazi

Wossack wrote: »

abs and bigger contact patch would put the average car driver ahead of the average biker in stopping distances I'd say

Modern bikes have ABS and combined braking

Mr.David

So, if the traction isnt based on contact area why have larger tyres?

Looking again at F=uN, for a fixed vehicle weight the only remaining variable that can increase your traction is u - the coefficient of friction.

So this is where the answer lies. Sticker tyres = more friction = more grip. But, stickier tyres wear quicker than harder compounds (obviously) and so you use wider tyres - the wear is spread across a wider contact patch and the tyres last longer than if they were sticky but narrow. So, the reason sports cars use wider tyres isnt for better traction - its for wear rate! (As well as for other things like heat management, rigidity under the stresses of cornering and braking and acceleration, etc.)

Wossack

Mr.David wrote: »

Pretty much. On a high level there is more contact area, but on a microscopic level there isnt a higher contact area due to the reduced load (which pushes less of the microscopic level surface in contact).

but as the load increases due to the weight transfer etc etc, the rubber isnt going to keep creating more and more friction indefinately - theres got to be a saturation point where the load overwhelms the available friction, and surely the increase in surface area would push this point out further..?

Wossack

KamiKazi wrote: »

Modern bikes have ABS and combined braking

I would hazard a guess at less then 5% of bikes in ireland have either... (probably quite a generous guess)

KamiKazi

Wossack wrote: »

I would hazard a guess at less then 5% of bikes in ireland have either... (probably quite a generous guess)

I have both, but the old version; right hand and foot

stevenmu

pajo1981 wrote: »

Interesting. Although there is more rubber in contact with the road, the weight of the vehicle is spread over a greater area, and so, there is no increase in traction.

Mr.David wrote: »

Pretty much. On a high level there is more contact area, but on a microscopic level there isnt a higher contact area due to the reduced load (which pushes less of the microscopic level surface in contact).

Out of curiosity, why then do sports cars have wider tires? Take for example F1 when they had the grooved tyres, the point of these was to reduce surface area in contact with the road which they claimed reduced traction.

Wossack

stevenmu wrote: »

Out of curiosity, why then do sports cars have wider tires? Take for example F1 when they had the grooved tyres, the point of these was to reduce surface area in contact with the road which they claimed reduced traction.

and slicks versus wets... sacrificing contact area to increase water channeling and avoid aquaplaning

swe_fi

VW 1 wrote: »

Having read a link in the thread below regarding the motorists being banned for doing 190-200kph on motorways, just wondering out of interest what is the quickest any of the guys here have done on motorways either in ireland or in germany where such speeds are legal?

245 km/h (on the speedometer) for 35 km solid approx (pedal to the floor the 90% of the time) in a Saab 9-5 Turbo , it was not in Ireland and on really good motorway. Car was surprisingly stable. What shocked me most is that it drinks FIVE liter / 10 km! - It said on the onboard computer and i verified it while filling up as well :-)

stevenmu

Actually quick google indicates it's to do with rubber strength. With more contact area the force is distributed over a larger area meaning a softer rubber can be used. The softer rubber has a higher coefficient of friction giving more traction/grip. With a smaller contact area the force is concentrated on a smaller area of rubber, meaning a harder compound has to be used giving a lower coefficient of friction and less traction/grip. A narrower tyre could use the same soft rubber but because the force would be concentrated on a smaller area of rubber it would wear much quicker.

Nice to learn something new.

keithclancy

KamiKazi wrote: »

Modern bikes have ABS and combined braking

From:

http://www.autoexpress.co.uk/carreviews/grouptests/224562/suzuki_gsx1300r_hayabusa.html

As with all motorbikes, the Suzuki struggles to match the braking abilities of most cars because of its tiny contact area on the tarmac. The two-wheeler posted the worst 70-0mph stopping distance here: 60.1 metres.

Edit:
Actually a fairly interesting article here:
http://everything2.com/title/Stopping+distance

KamiKazi

Ah don't mind that Hayabusas are overweight anyway

Mr.David

stevenmu wrote: »

Actually quick google indicates it's to do with rubber strength. With more contact area the force is distributed over a larger area meaning a softer rubber can be used. The softer rubber has a higher coefficient of friction giving more traction/grip. With a smaller contact area the force is concentrated on a smaller area of rubber, meaning a harder compound has to be used giving a lower coefficient of friction and less traction/grip. A narrower tyre could use the same soft rubber but because the force would be concentrated on a smaller area of rubber it would wear much quicker.

Nice to learn something new.

Thats it alright, as I posted a few posts back too

It is interesting and runs counter to popular thinking

For grooved tyres in F1 - wear rate will increase massively. Also, remember that friction is temperature dependant and that a smaller contact area will heat up more than a larger contact area over the same duty cycle and may overshoot the optimal range for friction.

Obviously they also affect handling etc.

Tigger

abs dosen't make you brake faster it stopps you skidding
sub 10 k bike can out brake all but the best of cars in the dry

any how back on topic

Mr.David

Tigger wrote: »

abs dosen't make you brake faster it stopps you skidding
sub 10 k bike can out brake all but the best of cars in the dry

any how back on topic

No it cant.

If F=uN, and you assume that the tyres on the car and bike are the same 'stickiness', the Normal force (weight) of the car will always be higher so it will always generate more traction allowing it to brake harder.

Also, most bikes cannot use all the traction they develop without flipping back over front!

BlackWizard

Fastest I went was just over 120mph on the M1.

What annoys me now is that my new car can barely go 120kph never mind mph

Tigger

so am i the winner with 305kmph

Cuddlesworth

Mr.David wrote: »

No it cant.

If F=uN, and you assume that the tyres on the car and bike are the same 'stickiness', the Normal force (weight) of the car will always be higher so it will always generate more traction allowing it to brake harder.

Also, most bikes cannot use all the traction they develop without flipping back over front!

I would have said its more to do with a combination of mass, contact area and center of gravity.

And while I'm not disagreeing with your logic, most sports bikes ride around with pretty soft compounds compared to a road legal sports car.

LookBehindYou

Tigger wrote: »

so am i the winner with 305kmph

NO:)

Tigger

why what are you claiming

fullstop

Tigger wrote: »

so am i the winner with 305kmph

No I did 306kph.

Tigger

fullstop wrote: »

No I did 306kph.

i put a scan of my gps up in my previous post
whats your proof?

Mr.David

Tigger wrote: »

so am i the winner with 305kmph

What were you driving?

Thats pretty rapid in fairness!:cool:

Tigger

gsxr1000k4

brakes seemed good

Mr.David

Tigger wrote: »

gsxr1000k4

brakes seemed good

I'm going to go right ahead and assume that's one of them two wheeled motorbike thingys!

You would be hopeful that the brakes were good once you reached 305kmph alright. Would be dissapointing if they werent!

Tigger

honestly i wouldnt like to touch the brakes above 250

keithclancy

Tigger wrote: »

gsxr1000k4

brakes seemed good

Imagine getting front tyre wobble at that speed ... jesus I wouldn't even get a chance to think "Game Over" ... Would probably get half way through the G and that would be it !

In fairness though... no car can compare to the acceleration/sensation of driving a quick bike that costs the same money.

borrowed a mates Suzuki SV650 with custom end can on it, went flat out from 0 - 120 *ahem within speed limits* was crazy .. was my first go on a decent bike

Got a spin in a mates Audi S3 and i nearly fell asleep by comparison..

Driving a car is more like a video game and driving a bike is like taming some sort of crazed wild animal.

KamiKazi

keithclancy wrote: »

Driving a car is more like a video game and driving a bike is like taming some sort of crazed wild animal.

Lmao

You're right though, cars are boring when you compare them to bikes.

Mr.David

Yeah bikes are fast - just make sure to stay away from corners

Runs Drives away and takes shelter

KamiKazi

Mr.David wrote: »

Yeah bikes are fast - just make sure to stay away from corners

Runs Drives away and takes shelter

We're not all on fat cruisers

keithclancy

Mr.David wrote: »

Yeah bikes are fast - just make sure to stay away from corners

Runs Drives away and takes shelter

Your not cornering properly if your footpegs don't hit the road

Mr.David

KamiKazi wrote: »

We're all on fat fag cruisers

Fixed that for you

Intended as a good natured poke only!

Mc Love

Tipped 100mph on the M7 all the cars around me were doing 90-95 MPH and i didnt want to be left behind

Tigger

Mr.David wrote: »

Yeah bikes are fast - just make sure to stay away from corners

Runs Drives away and takes shelter

on the real road in the dry there is no car that can keep up with a decent bike the acceleration and nimbleness is the issue

however you really need to be good to ride a bike safley you can gfet away with sooo much more ina car
i love them both

Tigger

keithclancy wrote: »

Imagine getting front tyre wobble at that speed ... .

just power through lol