KM vs Miles

[SpokeyDokey]

What's wrong with...

Miles to Km: Miles x 8/5

Km to miles: Km x 5/8

Accurate enough, especially with lower values.

 

[Dogtrousers]

What's wrong with...

Miles to Km: Miles x 8/5

Km to miles: Km x 5/8

Accurate enough, especially with lower values.

Nothing wrong with it but, being a bear of very little brain I find divisions and multiplications by 8 hard to do in my head.

Yeah, there are shortcuts but I don't find it all that easy. So I rely on my method which only requires divisions by 2 and 10 which are easy.

And if I'm not doing it in my head then I just multiply or divide by 0.6214

Plus, of course there are various "signposts" that I have by rote from things like riding audaxes (eg 200km = a wee bit less than 125 miles), and speed limits in France (eg 110km/h is a tad under 70)

 

[iandg]

I use kms on the bike, I find it easier working with metric OS maps. Convert imperial distances on road signs to KMs in my head when cycling but use miles when driving.

 

[NorthernSky]

i tried to use KM on strava but didn't really get used to it so have stuck with miles (might try again at some point )
i have now started to convert to metric when mentioning / recording my weight and height which took a bit of getting used to

 

[andrew_s]

Driving speeds and longer distances in miles ('cos road signs), everything else in km.
Pounds & ounces I have to convert before I've a proper feeling of "how much". Pints I just treat as half litres (which is what the pub pint frequently is if you discount the head).

Has anyone else noticed the removal of distances from non-trunk road signs?
Where a fingerpost at a rural junction may have originally said "village1 1¾; village2 3½" (on two lines), any modern replacement will just read "village1; village2".
My view is that it's a long term plan to reduce the cost of full metrification.

 

[Binky]

Always miles for me and feet for elevation.

What I find odd is some seem to record using the two methods. That is have miles ridden but have the elevation in metres. See this on Strava etc.

 

[Dogtrousers]

What I find odd is some seem to record using the two methods. That is have miles ridden but have the elevation in metres. See this on Strava etc.

I don't know why but I'll take guess.

I'm guessing it's just another example of the British half-and-half attitude to units, using a metric one here and imperial one there.

Metres of elevation because OS maps and pretty much everything else uses elevation in metres, feet are a bit of an oddity. Personally, I'll use feet for human height, but not for anything else. Miles, however, aren't an oddity because they are in common use, and on road signs etc.

 

[Alex321]

Always miles for me and feet for elevation.

What I find odd is some seem to record using the two methods. That is have miles ridden but have the elevation in metres. See this on Strava etc.

Not on Strava you don't, it won't let you (even in the paid version). I would much prefer to do that, because for some reason metres are more meaningful to me than feet. My Wahoo allows it, but as soon as it gets uploaded to Strava it is either miles and feet, or Km and Metres.

 

[presta]

It would certainly be no more ‘made up’ than the French and their metric system.

And imperial length units are defined in terms of metres. So they are just some random measure multiplied by some number.

All measurement units are arbitrary/random/made-up, that's not the difference between metric & imperial.

The point is that the SI system uses only one unit for each quantity, not multiple ones with arbitrary non-decimal ratios between them, and it also has a minimum number of arbitrary units, with the remainder derived from them. Thus it's possible to multiply force in Newtons by distance in metres for example, and get energy in Joules rather than Joules multiplied by some arbitrary conversion factor.

 

[Ming the Merciless]

All measurement units are arbitrary/random/made-up, that's not the difference between metric & imperial.

The point is that the SI system uses only one unit for each quantity, not multiple ones with arbitrary non-decimal ratios between them, and it also has a minimum number of arbitrary units, with the remainder derived from them. Thus it's possible to multiply force in Newtons by distance in metres for example, and get energy in Joules rather than Joules multiplied by some arbitrary conversion factor.

The imperial system is not arbitrary; it is based on centuries of practical use. In contrast, the metric system is criticized for being arbitrary, as its units are derived from a more abstract basis rather than practical experience.

 

[Andy in Germany]

Thus it's possible to multiply force in Newtons by distance in metres for example,

We're working on that at the moment, and I have enough trouble in metric thank you very much...

 

[andrew_s]

The imperial system is not arbitrary; it is based on centuries of practical use. In contrast, the metric system is criticized for being arbitrary, as its units are derived from a more abstract basis rather than practical experience.

The metric system is based on the metre being one 10 millionth of the distance between the north pole and the equator, and the density of water (1 kg = 10cm cubed). OK, the distance isn't something that's easily measured so there was a physical standard to compare against, but they got within 0.02% of being correct with it, which is pretty good IMO.

By contrast, the foot is based on the length of the human foot. This invites the question of whose foot? Everybody is different. This led to there being (before the metric system was developed) there being dozens of different lengths of the foot for different areas and different times, varying between about 10½ and 13½ (imperial) inches.

 

[Punkawallah]

The metric system is based on the metre being one 10 millionth of the distance between the north pole and the equator, and the density of water (1 kg = 10cm cubed). OK, the distance isn't something that's easily measured so there was a physical standard to compare against, but they got within 0.02% of being correct with it, which is pretty good IMO.

By contrast, the foot is based on the length of the human foot. This invites the question of whose foot? Everybody is different. This led to there being (before the metric system was developed) there being dozens of different lengths of the foot for different areas and different times, varying between about 10½ and 13½ (imperial) inches.

Until the ‘foot’ was standardised. Whether -your- foot was 13” didn’t matter, the -standard- foot was 12”. Much like the Metric meter being standardised despite the distance between the pole and the equator changing.

 

[Ming the Merciless]

The metric system is based on the metre being one 10 millionth of the distance between the north pole and the equator

Here I am, stood in field with the clothes I stand in. How do I use that definition to measure out an area?

By contrast, the foot is based on the length of the human foot.

Perfect, I have my measuring tools with me.

 

[Sea of vapours]

Here I am, stood in field with the clothes I stand in. How do I use that definition to measure out an area?

Unless it's a very small area then you pace it, which is roughly a metre, or roughly a yard, depending on your stride length. That's much easier than putting your feet end-to-end repeatedly. And the variance between people is similar to that for feet; quite possibly less. So both systems work equally well, albeit with a 10-20% inaccuracy, for that application, though the metre has the advantage, over the yard, of not being 'three of something smaller'. And once you have your result in square metres, converting to hectares is a good bit easier than to acres!