I'm 45. People of about my age may well remember this toy:
When I was very little I remember asking my dad what the "inch" scale on the ruler was about, and was met with a reassuring "oh it's an old measurement that you kids won't need to know about." Well, that certainly hasn't been the case.
I've ended up fluent in both Imperial and metric distance measurements, and a spell working at the fish counter and in the meat department in the local supermarket as a teenager gave me a bit of an idea of pounds and ounces (a pound is a good handful of mince, or haddock), as has baking cakes using recipe books I got from my mum. Other than that I'm probably mostly metric.
I certainly don't "get" the Fahrenheit scale, while it may seem intuitive to some it's just not as present in my day-to-day life as Imperial weights and distances are. I know what temperatures of low, mid and high 20s will be like, I have no clue how they equate to Fahrenheit temperature.
I'm certain though that a certain grumpy old sort will have seen Brexit as meaning a glorious return to buying their fruit and veg in ponds and ounces, though.
All the common imperial units are now actually derived from metric.
An inch is fixed at exactly 25.4mm, which makes a yard exactly 91.44cm and so on.
The pound is similarly defined as a precise number of grams.
I think the UK is fairly unique in using the two systems interchangeably.
Bikes are pretty bad for throwing together a mix of imp / metric: Your cranks are 170mm but the pedal treads are 9/16th. Your 150mm travel forks use a 1.25 to 1.125 inch steerer.
Cars and motoring are even worse though.
You drive a mile to fill up the car with 40 litres of petrol. On the way there you get 35mpg. Your engine has 247hp and 420N/m of torque. When you buy tyres they are 18" x 235mm. Stopping distances, height restriction and the space you should give a bike in the highway code are all in meters, but all speeds are still in mph.
Fractions aren’t as daft as they sound. Dead easy add and subtract without getting into the o.oooo1 precision.
Indeed, well, until you need to be more accurate than 1/16 or 1/32 anyway.
Because machining a crank down to 20/20 is so much easier when you have to do 1 13/16 minus 20/1000 in your head compared to 46.00-0.05.
And that's before you get into the quagmire of whitworth Vs UNC threads and spanners.
Your 150mm travel forks use a 1.25 to 1.125 inch steerer
But do they? I mean is the steerer tube actually made to an imperial measurement with a tolerance expressed in imperial or is it, in fact just commonly referred to as 1.25 inches but all the manufacturing, QA etc happens in the metric equivalent?
I may be splitting hairs, but isn't this just an anomaly unlike 27.2 seatposts where it's now expressed in mm, the forks are just a still described using "old money" but actually made to metric measurements? Genuine question from a pedant 🙂
@kelvin - I was just repeating a recent conversation with a US colleague (answering why they like using it)
PS with your name you're views are biased anyway !
There’s actually a good argument why Fahrenheit is easier for the general public to understand. If you say today it will be sunny with low 70s, or high 70s, that’s easy to grasp and there isn’t a huge difference between them. One is pleasant, the other is a bit hotter.
If you use deg C, then say today it will be in the 20s, it doesn’t work as well. 20C is nice, 29C is chuffin hot. People are simple, deg F is easier for most people to understand for weather. For other stuff it gets less useful very quickly!
That's familiarity, and is completely subjective. I haven't used Fahrenheit for years, and I couldn't tell you when the 70s go from pleasant to hot - I know both 71 and 79 are t-shirt weather, but that's about it.
When I was at university in the 80s doing mechanical engineering, one of the labs revolved around a hydraulic pump coupled to a hydraulic motor with some other bits and pieces. All the gauges used a mixture of different units. It was pretty much impossible to do the calculations - we all complained to the lecturer the next day. He had a good laugh - the whole point of the lab was to show how difficult it is mixing units, he wasn't really worried about us getting the calculations right.
I feel for anyone mixing imperial and metric. Thoughts and prayers.
There’s nothing wrong with fractions,
In the States, Wendy's introduced the 1/3 pounder burger, one upping McD's 1/4 pounder. It sold terribly, as people thought it was smaller.
The usability of the units individually depends entirely on your life experience as to whether you find a foot or a pint to be easy to visualise.
the benefits of metric is the interlinking. A 100mm cube of water is a litre, which weighs a kilo. A metre cube of water is a tonne if you are thinking bigger. Everything else you can reckon up with a basic estimate of linear distance, and density compared to water.
These are the useful ones for life, temperature and energy and so on are linked too.
But do they? I mean is the steerer tube actually made to an imperial measurement with a tolerance expressed in imperial or is it, in fact just commonly referred to as 1.25 inches but all the manufacturing, QA etc happens in the metric equivalent?
Yeah no doubt, especially given than inches are precisely defined in millimeters.
So 1.25" is exactly 31.75mm and 1.125" is exactly 28.575mm
Whether they actually round to 31.8mm and 28.6mm to meet the "standard" I don't know
I was just repeating a recent conversation with a US colleague
Well we all understand "sunny" better than just some numbers.
with your name you’re views are biased anyway !
It's 284K here today. I can see how that's much less intuitively useful than 11˚ (and less friendly than "in the low 50s"),
the benefits of metric is the interlinking. A 100mm cube of water is a litre, which weighs a kilo
and "a pints a pound the world around" - at least in the USA
I mean is the steerer tube actually made to an imperial measurement with a tolerance expressed in imperial or is it, in fact just commonly referred to as 1.25 inches but all the manufacturing, QA etc happens in the metric equivalent?
It probably depends where the factory is.
We make and export stuff worldwide, and the 'language of the factory' is metric. Many US customers send us imperial drawings which we re-draw in metric for manufacture (taking into account that rounding isn't allowed for tolerances, which means that the metric tolerances edge in slightly). When we send them the parts, they will check them to the imperial drawing.
But contrarily, kph is idiotic. the per hour introduces a 3600 which is definitely not helpful for anything.
Using m/s on the roads would make sense, practical range from zero to 40m/s, gives enough spread that multiples of five are useful subdivisions, no danger of getting to 3 figures (ruining road signs, and the aethetics of digital speedometers).
Might make people think about stopping distances too...
I feel for anyone mixing imperial and metric. Thoughts and prayers.
I've spent my entire career, just about, in the oil and gas industry so I got used to converting units very early on. The best argument against the use of imperial units is that to do anything meaningful with any measurement the first thing you have to do is convert to a metric type unit.
That being said Base 12 or Base 64 number systems have a lot to recommend them. Just a shame that imperial units don't use a consistent base number.
and “a pints a pound the world around” – at least in the USA
even in every country where its not, its a good approximation, but what happens when pints and pounds are not scale appropriate. How many ounces in a gallon?
Yea, not buying Fahrenheit being easier either.
There's actually some research done somewhere that determined people like scales around 30.
30kg is as much as you can sensibly carry
30C is a hot day
30 miles is (a bit longer) than a marathon
30meters is about as far as healthy eyes can read a number plate
30psi in your tires
Given several sets of units, people tend to settle on the one that puts 'normal' at about 30. E.g. at work I use all sorts of pressure units (kpa, bar, psi) but generally know the conversions to bar in my head as bar tends to be the one that gives you numbers that are 1-100 rather than 100,000.
But do they? I mean is the steerer tube actually made to an imperial measurement with a tolerance expressed in imperial or is it, in fact just commonly referred to as 1.25 inches but all the manufacturing, QA etc happens in the metric equivalent?
A 1.1/8 steerer is imperial (28.6mm) . But the bearing race at the bottom is metric(30mm).
A 1.1/8 headtube is 34mm though.
A 1.5 steerer is the same, 38.1mm, but 40mm where the bearing sits and a 44mm headtube. Then it all gets complicated as they add/subtract 0.1mm to achieve a tight fit!
How many ounces in a gallon?
Us or imperial?
Anyone who thinks metric has basically taken over and Imperial units are just used out of habit are delusional. If somone can do a quick search for 12.5 micron shim I could do with a bit right now...
Kpsi commonly used in our industry 😄🙄
I feel for anyone mixing imperial and metric. Thoughts and prayers.
The railways rang, they want a word.
ElShalimo
Free Member
“Metric after Brexit” is a very satisfying title“God on a quad” is equally pleasing
But "God on a Cod" makes for a better mental image.
The Fahrenheit scale makes no sense though: Set 0 at the freezing point of Brine ( to some unspecified water/salt mixture, for reasons lost to history), and 96 (not 100 obviously, as that would be way to straightforward) as the approximate temp of a "healthy man" (whatever that definition means, and a complete guess that turned out wrong anyway).
vs Celsius; 0 set at the point water freezes, and 100 at the point it boils...
Yeah, one seems slightly more intuitive than the other to me for some reason....
All the common imperial units are now actually derived from metric.
An inch is fixed at exactly 25.4mm, which makes a yard exactly 91.44cm and so on.
The pound is similarly defined as a precise number of grams.
Hang on...
So you think because you can convert one to another, they're derived from each other because it's "fixed at exactly" 1" = 25.4mm or 1 yard = 91.44cm and a Pound is defined as at a "precise" 453.592g.
In fairness when we're thinking about Imperial measurements, there may be some sense to that, no logic of course, but maybe it makes sense on some "it's the size of your Aunt Vera's big toe" Imperial measurement kind of way.
The Fahrenheit scale makes no sense though: Set 0 at the freezing point of Brine ( to some unspecified water/salt mixture, for reasons lost to history), and 96 (not 100 obviously, as that would be way to straightforward) as the approximate temp of a “healthy man” (whatever that definition means, and a complete guess that turned out wrong anyway).
The numbers were originally 1/4 of those values; nobody knows why Fahrenheit multiplied them all by 4 at some point. The numbers used were to do with factors and ease of divisibility - in the days before calculators using fractions made a lot of sense and it was originally devised by an astronomer who wanted 60th and 8th involved.
Good video here:
I've just rewatched the video and the Fahrenheit link to the expansion of mercury is interesting.
Plus, as a child of 1980s Scotland I wasn’t taught imperial measurements at school. I know what a kg looks like (as it’s about the same as a litre of Hartmann’s) but have no frame of reference for a lb, nor how many oz there are in it.
Well in those kind of approximations a lb is about 1/2 a litre of hartmann's (or a proper jar of jam) and there are 16 oz in a lb, which makes an ounce a smidge under 2 tablespoons of water.
do you describe your height and weight in kg and m? Bizarely despite being of the same era I still refer to humans in imperial...
Yes, describe my height and weight in metric. Why wouldn’t I?
Hang on…
So you think because you can convert one to another, they’re derived from each other because it’s “fixed at exactly” 1″ = 25.4mm or 1 yard = 91.44cm and a Pound is defined as at a “precise” 453.592g.
Imperial measures were originally derived from some physical, often human or animal definition. An inch is a 1/12 of a foot (inch being a rough translation of "twelfth" in Roman) and a foot was defined as well the size of a foot, exactly whose foot is lost to history.
But there were lots of competing definitions (there were Scottish feet, which were naturally a bit bigger)
In the 50's the Imperial measures were standardised and defined using precise metric measures. So they are now defined by metric measures and the metric SI units are all now derived from physical constants of the universe
Imperial measures were originally derived from some physical, often human or animal definition. An inch is a 1/12 of a foot (inch being a rough translation of “twelfth” in Roman) and a foot was defined as well the size of a foot, exactly whose foot is lost to history.
But there were lots of competing definitions (there were Scottish feet, which were naturally a bit bigger)
In the 50’s the Imperial measures were standardised and defined using precise metric measures. So they are now defined my metric measures and the metric SI units are all now derived from physical constants of the universe
Ah, I understand so pre 1950s imperial measurements weren't standardised. Thanks.
As a few people asked about the calculator on the previous page,
My first home when I was very young was a dairy farm. There's a few throwbacks from my grandparents still in this house, that was on the shelf under the stairs. I have no idea why, unless they kept it as a souvenir or curiosity.
I think the UK is fairly unique in using the two systems interchangeably.
I think we are, broadly, metric these days. Certainly for new stuff, it's legacy things that are killing us. Road signs for instance, the cost and labour involved in changing pretty much every single sign in the country would be astronomical and the benefit relatively minimal. Milk and beer is sold in 568ml servings, again the reason for this is pretty obvious - can you imagine the front cover of the Daily Express if we metricised the pint to 500ml?
There is still a small, gammony subset of the population still dreaming of halcyon days of pounds, shillings and pence and spending their retirements "correcting" footpath signs. But they're surely few and far between by now. Anyone under the age of 50 will have grown up all their lives being taught it, and much older than that and it's not like they've not had time to learn. It's wilful ignorance, the same attitude that would turn up their noses at anything other than meat & two veg as "foreign muck."
For me, being in my 40s I grew up with both, metric via school and imperial via (grand)parents. I'll favour metric but will use whatever's most convenient. Eg, I was measuring a drawer earlier this week, 407mm... oh, no, wait, it's 16".
Wendy’s introduced the 1/3 pounder burger, one upping McD’s 1/4 pounder. It sold terribly, as people thought it was smaller.
Missed a trick there, they should've changed nothing and called it the 2/8 burger.
This is happening with mobile phones now incidentally, have you noticed? Your standard widescreen ratio is 16:9, they're now doing ultra-wide screens at... 18:9.
and “a pints a pound the world around” – at least in the USA
Not even in the USA, it's an approximation. A pound is 454g, a US pint is 473ml. They're 20(ml|g) different.
vs Celsius; 0 set at the point water freezes, and 100 at the point it boils…
0'C is the melting point of ice, not the freezing point of water. I'm not really sure what the difference is, maybe there's a small gap or overlap, but my GCSE Physics teacher used to think it was important.
0’C is the melting point of ice, not the freezing point of water. I’m not really sure what the difference is, maybe there’s a small gap or overlap, but my GCSE Physics teacher used to think it was important.
My Science teacher used to say something like Water was as close to magic as could be found in real life because it didn't conform to many scientific norms. I'm sure he said 0c was the temp in which it could be found in all 3 forms, solid, liquid and gas.
He was however, a heavy drinker so... you know.
Yes, 0C is the triple point of water. He was right.
My GCSE memory is that it also contracts as it cools until about 4° or something where it starts expanding again. Or something. Great stuff, water.
EDIT : And that's why ice floats and fish don't die when ponds freeze.
Plus, as a child of 1980s Scotland I wasn’t taught imperial measurements at school. I know what a kg looks like (as it’s about the same as a litre of Hartmann’s) but have no frame of reference for a lb, nor how many oz there are in it.
A kilo isn't 'about the same as a litre,' it's exactly a litre (of water at any rate, I know not the density of whatever Hartmann's is).
This is the embuggerance of it all when people complain they don't understand metric. It's really not hard, I'm certain that in many cases it's rather they don't want to understand it.
For an approximation of what something 'feels' like, if you understand yards you understand metres. 100 metres up the road and 100 yards up the road are close enough for most practical purposes.
A kilo is 2.2 pounds. You don't know what 10kg is? It's 22lbs. Not good at maths then just double it, you'll be in the right ballpark. 7kg = 14lbs (plus a bit).
A mile is ~1.6km. Maths fail again? 5km is a smidge over 3 miles. I (hypothetically) ran the Manchester 10k last week. What's that gran, you don't know how far it is? It's six miles. (Plus about 400 yards but does that matter?)
Fahrenheit to Celcius. Most people I think know that the formula is C = (F-32) * 5 / 9, who's going to do that in their head? Converting say 76F, what's 220/9? But it's pretty easy to get accuracy to within 100ths of a degree (and I actually made this method up, I've no idea why it isn't taught anywhere). Subtract 32, add the result to itself shifted right one decimal place, halve the result. So as above, 76 - 32 = 44. 44 + 4.4 = 48.8. 48.8 / 2 = 24.4'C. [ The proper conversion comes out at 24.44(recurring)'C ]
Still too complicated? A fair approximation is to subtract 30 and halve it, you'll get within a degree or two if you're dealing in weather ranges. 76F - 30 = 46, /2 = 23'C.
Yes, 0C is the triple point of water. He was right.
Sorry, how do you get water vapour at 0'C?
Sorry, how do you get water vapour at 0’C?
Never seen vapour coming off of ice?
Ooo.... and snow and hail forming in clouds. In fact... clouds.
For me, being in my 40s I grew up with both, metric via school and imperial via (grand)parents.
Weirdly for me it's the other way around. But then my grandparents lived in (mostly) Europe c/o Foreign Office, and I always recall my grandmother talking "kilos" in the kitchen, with metric scales, and my mother always "pounds/oz" or volumetric measures of food, probably due to being in boarding school.
Certainly odd when I come across people younger than me that convert petrol price to gallon prices, and will never have seen fuel sold in gallons or pence per gallon, and probably young enough to have never seen orange squash sold in gallon containers either. I can only assume they're in the JRM mob when it comes to putting mpg and pence per l in to unified measurements.
Least a l is well defined. When talking gallon there's at least 2 different ones, and one can only make a guess as to which is meant from the accent.
Never seen vapour coming off of ice?
Huh. Good point. Funny thing, Physics.
In fact… clouds.
I thought one of the metrics was "at sea level pressure"?
When talking gallon there’s at least 2 different ones, and one can only make a guess as to which is meant from the accent.
Yeah, those Texans with their 8.3-gallon hats.
I thought one of the metrics was “at sea level pressure”?
Yeah, that was going off on a tangent. Sorry.
Stick with sublimation... even if it is nowhere near as interesting as the crazy cloud stuff (which I freely admit to not really understanding anyway).
The most ironic fact I ever learned about Metric and Imperial is that the bastion of inches and ounces that is the US of A defines the inch and pounds and ounces etc by metric equivalents.
But contrarily, kph is idiotic. the per hour introduces a 3600 which is definitely not helpful for anything.
Humans broadly understand speed, distance and time using km/h and mph to the point that in less densely populated places like Australia (and presumably US and Canada) people refer to distances in travel time (How far to Coffs Harbour - about an hour and half). Only NASA measures speed using seconds. Oh and probably Tesla cos they and their owners are special.
There have been attempts at metric time.
Never seen vapour coming off of ice?
That's not the ice vaporizing, that's water vapour in the warmer air condensing as it comes into contact with the colder object. Same as the steam you see coming out of your kettle isn't water vapour, it's the vapour condensing into liquid droplets in the cooler air.
The triple point of water is at 0.01 C, but only at a specific pressure too - so it doesn't happen on the Earth, in natural circumstances. The altitude on Mars is measured from where the atmospheric pressure is that triple point pressure - above this altitude water sublimates from solid to gas, with no liquid phase.
There have been attempts at metric time.
Until fairly recently Kodak used the metric calendar internally.
