MPH or KMH?

[DaveReading]

For a salutary lesson in what can go wrong when you confuse pounds and kilograms, Google "Gimli Glider".

[Tim Hall]

Since I moved to Germany in 2014 I have gone fully metric. I remember switching my Garmin from imperial to metric on my first day here - a kind of mental switch flipped then too. I haven’t needed imperial at all since I’ve been here except for Mum’s pancake recipe (4 plz flour, half a pint of milk, one egg).

What is plz?

(And is it an imperial or metric egg?)

It depends whether it's from an African or European Swallow.

[quixoticgeek]

No it doesn’t mean I think everyone should do it the same. Not being prescriptive at all. Saying something is necessary is bring prescriptive, saying something is a want is the opposite.  You want those things that’s fine, but they are not necessary.  It’s your choice to do it that way. Just as it’s my choice to do it without them. 

Then your wording is bad.

So in your case necessary from a subjective point of view , but not necessary from an objective point of view.

Well given that necessary boils down to oxygen, shelter, food, water, and company, yes, noone needs any form of measurement. Same as noone NEEDS to ride a bike. However if we assume that people ride bikes, then there are many situations where a cyclists can need to know distances, and from distances other derived information, such as speed, and estimated time of arrival.

So you are quoting me and attempting pedantry that is completely unconnected with the quote?

I quoted you and asked a question, for it was unclear what your post referred to. Now you have clarified it a bit. 

“... given the weird conversions between different measurements within the imperial system...” is pretty specific. It certainly explains why imperial is inferior to metric.

Converting between imperial units is bloody confusing, say for example you have 32oz of liquid paint, and you are putting it in a 1 cubic foot tank. How much of the tank will be filled afterwards? Or I have 1 square foot, how much is that in square yards? And it can get even more confusing when you want to convert them to sensible^Wmetric esp when you get into things like "I need a number 7 drill, in metric".

I can never understand US backpacks sold in cubic inches of volume, it's a right pain to convert that to litres. Ditto US scuba tanks that are sold as their capacity of 14.7psi air, when compressed into the tank at the operating pressure. So an 80cuft tank, what is the maximum pressure I can fill this to? Where as in the rest of the world we'd say a 12l 232bar tank. Which has an empty volume of 12l, and max operating pressure of 232 atmospheres.

It's a lot easier when everything shares the same base.

I can highly recommend everyone listen to this episode of 99% invisible:

https://99percentinvisible.org/episode/half-measures/

I can see certain elements within parliament are going to push to make the UK go back to using imperial units for everything. Which aside from the fact that UK imperial units do not match with the largest remaining user of imperial units, the US. Try fitting 8 UK pints into 1 US gallon... Is going to be a really really bad idea.

Over the last 50 years or so engineering within the UK has moved everything to being metric. The tooling is all metric (tho they probably have a draw labelled "Imperial drill bits"). Converting to imperial just to fullfil the wet dreams of a haunted Victorian coat rack, would be *REALLY* bad for UK industry.

The UK should move away from selling beer in pints. The UK should move away from having Miles on it's road signs. If the UK government is serious about "Global Britain" then we need to recognise that only the US and Myanmar use imperial units. The rest of the world use metric, and the UK needs to grow up and recognise this.

However, in the context of space disasters, it's another learning issue.

All measurement systems are arbitrary, it's probably something to do with human diversity.

Yes. They are arbitrary. The metre is defined as some division of the distance from the North Pole to Paris or the equator or some such.

The yard is defined as 3 feet, the foot is 12 inches, and an inch is 3 barley corns plump and round, laid end on end.

Both are arbitrary. However, what makes the metric more useful to use, is that if I have 1000m I have a kilometre. If I need something smaller than a meter, I can use centimetres, or millimetres, or micrometers. And if I have to mix the two, to work out say, how much volume I would need, in order to cover a square kilometre with something to a depth of 10 micrometers, I can easily do that. (1000*1000)*(0.000010) or 10m³. Now, let's say I wanted to cover a square mile to a depth of 0.250". That is a damn site more complicated maths. Esp as when you've got that in cubic whatevers (would that be cubic miles, or cubic inches?), when you go to buy the stuff, it's going to come in gallons...

Yes all measures are arbitrary. Not all measures are logical.

J

[FifeingEejit]

On several hiking sites I use, eg https://www.walkhighlands.co.uk/ the times given seem to assume a zimmer frame is involved.

Aye, when using them a few club members knock off a couple of hours, though on a couple of occasions the WH times have proven to be right or even underestimates...
It's particularly bad when it's the person who's in charge of the meal that's late back.

[cygnet]

Speed: mph (predominantly used for walking, commuting, driving/being driven), not displayed on cycling computer; this does make leading cycle club rides at a defined (in kmh) pace "interesting"...

Distance:
Cycling - Distance to go in km, doing mental conversions to miles to go and commutes to go depending on fatigue and teidium levels. If not following a route, no distance displayed.
Exceptions for racing:

• Standard Distance TT - distance travelled in miles
  
• Duration TT - distance travelled in units according to the target I've set

Driving/being driven - miles
Walking - miles (Hiking with an OS map - routes plotted in km, converted to miles)

[Cudzoziemiec]

I can never understand US backpacks sold in cubic inches of volume, it's a right pain to convert that to litres.

Several years ago, someone wrote to a cycling magazine (I think it was the CTC), complaining about panniers, bar bags and such like being described in litres. They didn't want to know the size in cubic inches or fluid ounces. What they wanted was some indication of shape, which is totally missing from either litres or cu. in. but rather useful when packing.

[Kim]

I can never understand US backpacks sold in cubic inches of volume, it's a right pain to convert that to litres.

Several years ago, someone wrote to a cycling magazine (I think it was the CTC), complaining about panniers, bar bags and such like being described in litres. They didn't want to know the size in cubic inches or fluid ounces. What they wanted was some indication of shape, which is totally missing from either litres or cu. in. but rather useful when packing.

A reasonable request, but pretty much impossible to standardise^[1], other than by manufacturers publishing dimensional drawings of the bag in question, which they really ought to.

I suppose a magazine could usefully have a standard selection of objects and report which ones would and wouldn't fit in a given bag.  I'm reminded of a friend who, while shopping for a new freezer, used jigsaw puzzle boxes as a unit of comparison.


_{[1] There's a circle of hell where you're made to spend eternity searching for enclosures by size on the Farnell website.}

[Cudzoziemiec]

Given almost all panniers and bar bags are a flavour of cuboid, I think what they wanted was probably simple width x depth x height. This wouldn't work so well with saddlebags and not at all with frame bags, though it was before those returned to favour.

Ed: And "bikepacking bar bags" being cylindrical could easily be described in terms of diameter x length.

[Kim]

Given almost all panniers and bar bags are a flavour of cuboid, I think what they wanted was probably simple width x depth x height. This wouldn't work so well with saddlebags and not at all with frame bags, though it was before those returned to favour.

Yeah, that's not unreasonable, as long as it's clear which dimension is which.

[Rod Marton]

Driving: mph (mainly ecause speed limits are given in these).
Cycling/walking: kmh (partly from audax, partly from touring abroad, partly because they look bigger).
Professionally: ms^-1.

I'm bilingual between mph and kmh, so I could quite happily use either. I would have to think a bit more to convert to ms^-1, but there isn't generally much overlap in application.

[Jaded]

The UK should move away from selling beer in pints. The UK should move away from having Miles on it's road signs. If the UK government is serious about "Global Britain" then we need to recognise that only the US and Myanmar use imperial units. The rest of the world use metric, and the UK needs to grow up and recognise this.

If the world is serious about this pedantic nonsense, everyone should speak the same language.

[Hot Flatus]

I hate all this far-right anti-diversity shit

[zigzag]

i can use both (having lived in the us and uk), but prefer everything in km. miles into km conversion is easy: miles x 1.5 and add a bit.

most cyclists i know in london (not audaxers) talk/think in km, perhaps because younger generation?

[Syd]

I mix running with cycling and use km. Most running events are in km so it all just works..

[Kim]

Thanks for correcting me on Decimal Day, Dave. I have lost track of when the changeover came, sometime between starting secondary school in 1969 using inches and leaving in 1974 by which time we were measuring in mm.

AIUI the school curriculum is a thing unto itself, and the change to metric there was unrelated to decimal currency^[1] or the government's use of metric for standards (even imperial ones).  Indeed, I believe that individual schools set their own curriculum until 1988.


_{[1] Primary exercise books were full of "New Pence" in the mid 80s.  I deduced that this referred to the special plastic currency used for maths lessons, rather than the type used by adults to pay for things in shops.}

[Ian H]

Indeed.  Back in the 60s we were taught metric measurements, just in case we should ever come across them.

Personally, I think the current confusion of systems adds colour to life.  And humour (see this thread).

[Tim Hall]

Km. Measurements went metric on Decimal Day in 1971

They most certainly did not - the only thing that changed on Decimalisation Day was the currency.

Hence, 50 years on, our road signs still show miles and pubs still sell pints.

Thanks for correcting me on Decimal Day, Dave. I have lost track of when the changeover came, sometime between starting secondary school in 1969 using inches and leaving in 1974 by which time we were measuring in mm.

After both the Chatterly Ban _and_ The Beatles first LP. 

[Davef]

It is not just a preference. Metric units are a coherent set of units. Metric is also decimal. Imperial units are neither.

1 litre is 1000 cubic centimetres and a litre of water weighs 1kg. It takes one kilojoule to raise it temperature by 1 degree centigrade and to do this in one second requires 1 kilowatt of power.

How many cubic inches is a pint of water and how many pounds does it weigh ? How many horsepower do you need to raise it temperature by 1 degree Fahrenheit per sec ?

I have no objection to beer being sold in pints but I would not use them to calculate fuel usage for my spaceship.

[Wowbagger]

Km. Measurements went metric on Decimal Day in 1971

They most certainly did not - the only thing that changed on Decimalisation Day was the currency.

Hence, 50 years on, our road signs still show miles and pubs still sell pints.

Thanks for correcting me on Decimal Day, Dave. I have lost track of when the changeover came, sometime between starting secondary school in 1969 using inches and leaving in 1974 by which time we were measuring in mm.

After both the Chatterly Ban _and_ The Beatles first LP.

"Decimal Day" (15th February 1971) was after the *Beatles' last LP. We'll be celebrating its 50th anniversary next month. I think it was considered necessary in order to persuade the French that we were actually serious about wanting to join the EEC. How long until Fartrage campaigns for the return of £ s d?

Re the previous post, "A Pint of Water weighs a pound and a quarter". Surely everyone know that? Unless they are USAnians, in which case their pints are (I believe) actually 0.8 pints.

*A popular beat combo, m'lud.

[Hot Flatus]

i can use both (having lived in the us and uk), but prefer everything in km. miles into km conversion is easy: miles x 1.5 and add a bit.

most cyclists i know in london (not audaxers) talk/think in km, perhaps because younger generation?

Plus if you're cycling in kms and everyone else in miles, it means you'll be going faster than them too

[Cudzoziemiec]

How long until Fartrage campaigns for the return of £ s d?

I don't think it ever went away, if you know where to ask, though the Romans are more popular nowadays: MDMA.

[Wowbagger]

How long until Fartrage campaigns for the return of £ s d?

I don't think it ever went away, if you know where to ask, though the Romans are more popular nowadays: MDMA.

The *Beatles had a song about that too.

*a popular beat combo, m'lud.

[Davef]

Km. Measurements went metric on Decimal Day in 1971

They most certainly did not - the only thing that changed on Decimalisation Day was the currency.

Hence, 50 years on, our road signs still show miles and pubs still sell pints.

Thanks for correcting me on Decimal Day, Dave. I have lost track of when the changeover came, sometime between starting secondary school in 1969 using inches and leaving in 1974 by which time we were measuring in mm.

After both the Chatterly Ban _and_ The Beatles first LP.

"Decimal Day" (15th February 1971) was after the *Beatles' last LP. We'll be celebrating its 50th anniversary next month. I think it was considered necessary in order to persuade the French that we were actually serious about wanting to join the EEC. How long until Fartrage campaigns for the return of £ s d?

Re the previous post, "A Pint of Water weighs a pound and a quarter". Surely everyone know that? Unless they are USAnians, in which case their pints are (I believe) actually 0.8 pints.

*A popular beat combo, m'lud.

Well that is what happens when you have a floating exchange rate between pounds and dollars.

[Kim]

What's the exchange rate between pounds and hashes?

[Jaded]

Ah yes, universal currency needed to go alongside the universal language...

Let's standardise everything!!!!!!