# Why kms?

#### RichardB

##### Slightly retro
Imperial all the way, except fractions. mm are much easier to visualise and comprend than 3/32, 8/11th etc
I grew up with Imperial, but I'm happy to use either. I think the advantage of the Imperial system is that it is based on human dimensions (inch = thumb joint, foot = foot, mile = 1000 steps, furlong, chain, etc) so it is more intuitive than a system based on the length of a random steel bar in a fridge somewhere. But with the advent of calculators and computers, there is no question that metric is easier and more useable. We will eventually be 100% metric, I am sure, but I will regret the passing of the old system. However, if I feel too nostalgic I always remember a conversation I had on a motorcycle forum where we were discussing tuning modifications. An American guy chimed in with (to paraphrase) "What you need to do is machine about nineteen and one-half sixty-fourths from the surface of the cylinder head." Now that IS crazy.

FWIW, when I make a table, I plot out in my head the length in feet, the height in inches, and the wood stock in inches or board feet, because these make more sense to me. When I do the actual making, everything is in cm, except for any intricate joints, which I measure in 1/10th mm, because calculations are simpler. Horses for courses.

#### figbat

##### Slippery scientist
I grew up with Imperial, but I'm happy to use either. I think the advantage of the Imperial system is that it is based on human dimensions (inch = thumb joint, foot = foot, mile = 1000 steps, furlong, chain, etc) so it is more intuitive than a system based on the length of a random steel bar in a fridge somewhere.
Oh come now, it's not that difficult. A metre is defined as the distance travelled by light in a vacuum in 1/299,792,458 of a second; how is that not easy to visualise?

Horses for courses.
Now THERE is an imperial animal - measured in hands (4 inches) and raced over furlongs and miles.

#### RichardB

##### Slightly retro
Oh come now, it's not that difficult. A metre is defined as the distance travelled by light in a vacuum in 1/299,792,458 of a second; how is that not easy to visualise?
You are quite correct. The metre bar hasn't been used since 1960. Just one more way in which I am falling behind.

Back with you in a couple of microfortnights.

#### Andy in Germany

##### Guru
Oh come now, it's not that difficult. A metre is defined as the distance travelled by light in a vacuum in 1/299,792,458 of a second; how is that not easy to visualise?
This is what happens when nerds are put in charge of defining things.

#### figbat

##### Slippery scientist
This is what happens when nerds are put in charge of defining things.
In defence of nerds, it is, at least, consistent and unchanging which a physical item is not. The kilogram is was the last remaining SI measure that is defined by the thing rather than a concept; the search continues is over (now I am behind the times as I didn't realise they had found an absolute definition - the kilogram is now defined by taking the fixed numerical value of the Planck constant to be 6.62607015×10^−34 when expressed in the unit J⋅s, which is equal to kg⋅m^2⋅s^−1, where the metre and the second are defined in terms of c and ΔνCs.

#### matticus

##### Über Member
In defence of nerds, it is, at least, consistent and unchanging which a physical item is not.
I think they should just crowd-source this stuff - it would be obvious if it ever drifted significantly out of whack. Would save a lot of money (that we could spend on feeding poor countries and new iPhones).

#### figbat

##### Slippery scientist
I think they should just crowd-source this stuff - it would be obvious if it ever drifted significantly out of whack.
They crowd-sourced the current US president...

#### Andy in Germany

##### Guru
In defence of nerds, it is, at least, consistent and unchanging which a physical item is not. The kilogram is was the last remaining SI measure that is defined by the thing rather than a concept; the search continues is over (now I am behind the times as I didn't realise they had found an absolute definition - the kilogram is now defined by taking the fixed numerical value of the Planck constant to be 6.62607015×10^−34 when expressed in the unit J⋅s, which is equal to kg⋅m^2⋅s^−1, where the metre and the second are defined in terms of c and ΔνCs.
I'm sure that makes logical sense, but I don't really understand most of it...

#### Dogtrousers

##### Kilometre nibbler
I grew up with Imperial, but I'm happy to use either. I think the advantage of the Imperial system is that it is based on human dimensions (inch = thumb joint, foot = foot, mile = 1000 steps, furlong, chain, etc) so it is more intuitive than a system based on the length of a random steel bar in a fridge somewhere.

The thing is: It isn't really based on human dimensions. Some people's feet are about a foot long - but most people's aren't. The chain? Yes, very intuitive - although I prefer the standard "piece of string". The furlong? errrm a long furry thing?

The metre was originally defined as one ten-millionth of the distance from the equator to the North Pole along a great circle which is far more intuitive. You just close your eyes and imagine the distance from the equator to the north pole, and then divide it into 10 million. Simples

But like you, and I'm sure many people, I'm entirely happy with either because I've dealt with both a lot. With some exceptions: My bathroom scales are marked out in kilos and stone, so both make sense to me. But any weight (of people or things or stuff) expressed American style in pounds makes no sense to me at all. And I never learned oz or fl oz because I never had to - apart from rolling tobacco as in "Half an ounce of Golden Virginia" or if I was incredibly flush "A two ounce tin".

Last edited:

#### matticus

##### Über Member
5 - 8 - 13 - 21 - 34 - 55 - 89 ...
Ladies n gennulmen, we present to you: the new Campag Gravelissimo cassette! Italian beauty+maths

#### Notafettler

##### Guest
In my day you could get 8
In my day A penny would get you a lorry load
And the lorry

#### Chap sur le velo

##### Regular
I think the advantage of the Imperial system is that it is based on human dimensions ... mile = 1000 steps...so it is more intuitive
Blimey with a stride of over 5' you get no argument from me, big fella.

#### RichardB

##### Slightly retro

The thing is: It isn't really based on human dimensions. Some people's feet are about a foot long - but most people's aren't. The chain? Yes, very intuitive - although I prefer the standard "piece of string". The furlong? errrm a long furry thing?
No, I disagree. The old measurements were based on human dimensions, but in the vast majority of cases there was no need to be absolutely precise. A foot is about the length of an average adult foot, for example. A mile was a thousand steps (the Roman mille passus), again variable with stride length, but a useful concept. There were plenty of more precise measurements (troy and avoirdupois ounces, drams and the like for commercial purposes, for example) for when accuracy was needed. But for day-to-day transactions, 'about a foot', 'about an inch' and 'about a mile' were adequate. A furlong was originally a 'furrow-long' - the length of an average furrow in a field. In a society where the majority of people worked on the land, that would have been a useful mental image to describe a distance. Again, originally it would have been an approximate distance, and only became defined as 1/8 mile or 220 yards much later. Agreed, the more people needed to calculate rather than estimate, the clumsier and more frustrating the old system became. But its basis in human factors is why I think people feel comfortable with it.

But like you, and I'm sure many people, I'm entirely happy with either because I've dealt with both a lot. With some exceptions: My bathroom scales are marked out in kilos and stone, so both make sense to me. But any weight (of people or things or stuff) expressed American style in pounds makes no sense to me at all.
I'm with you here. I think of my weight as 'something stone something' and always have. If I'm watching it go up or down, I tend to measure in kilos for all the obvious reasons. But a 200lb person - are they ridiculously skinny or a lump of lard? I'd have to divide by 14 to have a clue to the answer. 2lb of flour, no problem. 200lb of adult - reach for the calculator.

#### RichardB

##### Slightly retro
Blimey with a stride of over 5' you get no argument from me, big fella.
The Romans (mille passus) measured a step to where the same foot touched the ground, not one foot to the other, so a stride length of about 2' 9", which is my own stride length, give or take. We're not so different.

#### matticus

##### Über Member
People disagree, but I STILL say that the easiest numbers to think about are quantities you can see in your head.
e.g. 3 apples? easy. 7? Yeah sure. 33? Well, sort of, certainly harder. 77? well, it's a big pile isn't it! But you wouldn't be very accurate :P