scott wrote:
>> Well, I've seen quite a few cars, and almost all of them had 4 gears.
> 
> Funny, I usually take about 10 rental cars per year and I don't recall 
> any of them ever having 4 gears, even when I picked the absolute 
> cheapest one they offered.  Can you give any examples?
> 
>> And yet, the gears are spaced so that changing gear is only useful at 
>> speeds below 50 MPH. Once you're doing more than 50, you're in top 
>> gear and there's no advantage.
> 
> Some people like to accelerate above 50 MPH you know :-)  I suspect at 
> 50 mph in your car you still have the choice of 3rd, 4th, 5th and 6th 
> gears, how is that not useful?  Even at 80 mph I suspect that 4th gear 
> would still be available to give you the maximum acceleration (should 
> you ever need it). That's the idea of gears.

Doesn't match what I have observed. If this were the case, it would be 
*useful*, and indeed this is was I was expecting to find.

On the contrary, it appears that unless you're in 6th gear, you can't 
exceed about 65 MPH.

If the gears were more spaced out, then at high speed I'd have a choice 
of gears, and I could use that to get more acceleration. But no, the 
gears are all bunched up at the low speeds, where I didn't have an 
acceleration problem in the first place, even with my old Pergeot with 
just 4 gears. This is what's puzzling me.

>> It's just that when the engine revs get high, you feel like you should 
>> be changing up a gear. (But there aren't any.)
> 
> Driving around at low revs might be fine at low speeds, but at higher 
> speeds you *need* the higher rpms to generate the power to overcome the 
> air drag. 6th gear is designed specifically so that the engine is 
> developing its maximum power at the top speed of your car, otherwise you 
> wouldn't be able to reach that speed!

Mmm, OK.

BTW, is drag proportional to speed linearly? Or quadratically? Or...?

>> Interesting. I always through disk brakes are cheaper, so they use 
>> those where they can't afford to fit propper drum brakes.
> 
> Hehe no, otherwise F1 cars would use drum brakes and cheap cars would 
> use disc brakes.  It's the other way around.

It's news to me that it *is* the other way around. I thought F1 cars had 
drum brakes. (You'll be surprised to hear that I haven't actually taken 
too many F1 cars apart.)

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Invisible <voi### [at] devnull> wrote:
> I have a new car.

  I don't have even a driver's license.

-- 
                                                          - Warp

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Warp wrote:
> Invisible <voi### [at] devnull> wrote:
>> I have a new car.
> 
>   I don't have even a driver's license.

This does not preclude you from owning a car. Only from driving one. On 
a public road. Which is basically the only sane reason for owning a car 
in the first place. But still! What was I talking about? Hmm...

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> On the contrary, it appears that unless you're in 6th gear, you can't 
> exceed about 65 MPH.

Wow.  Are you really saying that at 60mph the RPMs in 5th gear are at 6000 
or something?  That sounds more like 3rd gear in my car - I can see now why 
you are annoyed!

> BTW, is drag proportional to speed linearly? Or quadratically? Or...?

Roughly speed squared.  But the power needed to overcome a certain force is 
also proportional to the speed.  So in the end the power needed to maintain 
a certain speed is proportional to speed cubed.

> It's news to me that it *is* the other way around. I thought F1 cars had 
> drum brakes. (You'll be surprised to hear that I haven't actually taken 
> too many F1 cars apart.)

You used to be able to see them easily before they started using those silly 
bits of aerodynamic plastic around them.  You can also sometimes see the 
discs glowing bright orange through the wheel under heavy braking.

http://static.howstuffworks.com/gif/formula-one-12.gif

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Warp wrote:

>   I don't have even a driver's license.

Fun fact: I passed my driving theory test first time. One of the 
questions was this:



[Picture of a sign. It's red, octagonal, and says "STOP" in large white 
letters in the middle.]

What does this sign mean?

A. Stop.
B. Stop if there is traffic coming.
C. Stop if you feel like it.
D. Go.



I'm not kidding. That's really what option C actually said.

I can see somebody geniunely thinking that B might be the correct answer 
I suppose. But beyond that, the only sane reason I can see for this 
question even existing is that some applicants might be so bad at 
English that they can't actually comprehend road signs. Certainly there 
are plenty of signs far more obscure than this.

(For example, a blue circle with red edges and a red cross through it. 
Wanna take a guess what that means?)

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>> On the contrary, it appears that unless you're in 6th gear, you can't 
>> exceed about 65 MPH.
> 
> Wow.  Are you really saying that at 60mph the RPMs in 5th gear are at 
> 6000 or something?  That sounds more like 3rd gear in my car - I can see 
> now why you are annoyed!

I didn't actually check the rev count, but in 5th gear, the car seems 
very reluctant to go much faster than roughly 65. Which means that if I 
want to drive on a motorway, I literally *have* to switch to 6th - 
difficult as that is. If it weren't for this, I probably just wouldn't 
use 6th at all.

Like I say, in 1st gear, accelerating generally isn't an issue, no 
matter how whimpy your car is. It's when you're zooming down a motorway 
that there's no acceleration left, so that's where I would have expected 
extra gears to be added.

>> BTW, is drag proportional to speed linearly? Or quadratically? Or...?
> 
> Roughly speed squared.  But the power needed to overcome a certain force 
> is also proportional to the speed.  So in the end the power needed to 
> maintain a certain speed is proportional to speed cubed.

I see... That would explain the statistic about the Bugatti Veyron only 
needing 100 horsepower to get up to 100 MPH, but needing a further 800 
hp to get up to top speed. (Or something like that.)

>> It's news to me that it *is* the other way around. I thought F1 cars 
>> had drum brakes. (You'll be surprised to hear that I haven't actually 
>> taken too many F1 cars apart.)
> 
> You used to be able to see them easily before they started using those 
> silly bits of aerodynamic plastic around them.  You can also sometimes 
> see the discs glowing bright orange through the wheel under heavy braking.

Ah yes, F1 cars, the ultimate example of engineering in the raggid edge. :-)

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Invisible <voi### [at] devnull> wrote:
> On the contrary, it appears that unless you're in 6th gear, you can't
> exceed about 65 MPH.

Haha, I drive an 18 year old 1.1L peugeot (also 5 gears - there's another data
point ;-) and regularly exceed 65mph in 4th - indeed, it's often the only way I
can get up to motorway speed quick enough on certain slip roads!

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> Like I say, in 1st gear, accelerating generally isn't an issue, no matter 
> how whimpy your car is. It's when you're zooming down a motorway that 
> there's no acceleration left, so that's where I would have expected extra 
> gears to be added.

It seems your car is just badly designed then, in most cars I've driven at 
65 mph you can easily switch down 1 or 2 gears to get more acceleration 
without going anywhere near the redline of the engine.  In fact in my first 
few cars you *had* to do this when the motorway went up a hill, otherwise 
you'd gradually come to a stop!  MAybe you were in 3rd gear instead of 
5th...  It seems to be that in 3rd gear you'd get stuck at about 65mph and 
not be able to go much faster - I'll try it on my car on the way home :-)

> I see... That would explain the statistic about the Bugatti Veyron only 
> needing 100 horsepower to get up to 100 MPH, but needing a further 800 hp 
> to get up to top speed. (Or something like that.)

Yup, if you want double the top speed you need 8x the power!

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Invisible <voi### [at] devnull> wrote:
> In the category of "I realise nobody actually gives a damn but I'm going
> to tell you all anyway": I have a new car.

yet into that category, here's another useless tidbit:  I don't drive cars.  I
don't know how and I don't give a damn, I just take the bus or subway.

I suck at driving even at games so I thought I'd be putting people's lifes at
danger behind a wheel. :)

so, there you go:  a highly useful skill you've got and I don't.  should make
your day... :P

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Bill Pragnell wrote:
> Invisible <voi### [at] devnull> wrote:
>> On the contrary, it appears that unless you're in 6th gear, you can't
>> exceed about 65 MPH.
> 
> Haha, I drive an 18 year old 1.1L peugeot (also 5 gears - there's another data
> point ;-) and regularly exceed 65mph in 4th - indeed, it's often the only way I
> can get up to motorway speed quick enough on certain slip roads!

My 4-gear Peugeot 1.1 seemed happy to do 60 or so in 3rd gear. But then, 
while it had a small engine, it was also pretty light too...

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