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Going Metric

Britain like the US resists going completely metric even though logically it makes sense to measure or count stuff in multiples of ten.

The US has always had a decimal monetary system. 100 cents equals one dollar. Real simple.

If you have 10095 cents, you simply stick a decimal point two digits in from the left, like so, 100.95 and you have 100 dollars and 95 cents.

Britain too has decimal money. 100 pennies equals one pound. It wasn’t always like that, the new currency was introduced in 1971, and I remember it well. I grew up with a system where 12 pennies made one shilling, and 20 shillings made one pound.

So in the previous example, 10095 British pennies first had to be divided by 12 to get 841 shillings and 3 pennies. Then divide the 841 shillings by 20 to get pounds, for a final amount of 42 pounds, 1 shilling, and 3 pence. A nightmare if you worked in retail.

Measuring length or distance is no different. 12 inches to a foot, 3 feet to a yard, and 1,760 yards to the mile. However, unlike money we hardly ever have to buy a mile length of anything and chop it up into one inch pieces. We don’t really need to know how many inches in a mile.

We do know what an 8 foot length of lumber looks like, and if necessary we can figure out how many 8 foot lengths we need to make a certain number of pieces measured in inches. But if the metric system is forced on us, and they start to sell lumber by the meter, there would be an outcry I am sure.

The same if you go to the grocery store to buy a quart of milk, or 10 lbs. of potatoes, and find those items are now measured in liters or kilos. There would be confusion and aggravation.  We also know how fast 30 mph. is, but 50 kilometers per hour, how fast is that? (Actually just over 31 mph.)

Britain is under more pressure to go completely metric because they are a member of the European Union where most other member countries are already metric.

I say leave people alone and let them use whatever they are comfortable with. Change will happen when the old system is no longer practical.

Even in industry in the US, many companies are manufacturing items measured by the metric system. They do this out of necessity when their product is being sold overseas.

When I built frames in England I built them in 1/2 inch increments.  21 inch, 21 1/2 inch, 22 inch, 22 1/2 and so on. When I came to the US, because of the huge influence of Italian made frames, customers asked for frames in centimeters. So I started building 53cm. 54cm. 55cm. 56 and so on. I didn’t fight it, it just made sense to do that.

Back in the 1980s and before that, the standard measurement for bicycle frame tubes were a 1 inch top tube, 1 1/8 inch seat and down tube, and a 1 1/4 inch head tube. Even Italian builders used these same Imperial sizes. (The French being extremely nationalistic would never use British Imperial measurements, and everything on their frames is metric.)

An English bottom bracket thread is 1 3/8 inch diameter, and 24 threads per inch. An Italian BB is slightly bigger at 36mm. and strangely the same 24 threads per inch and not metric. I wonder what happened at the meeting when that standard was decided on.

Traditionally, on English and for most of the rest of the world, front fork steering tubes were always 1 inch and threaded. In the 1990s when threadless steering tubes and headsets were introduced, there was an opportunity to go metric. However, the size chosen was 1 1/8 inch. (Were the Italian bottom bracket people at that meeting too.)

As a final word, I predict, (Though I will never live to see it.) when planet Earth has gone completely metric, and Imperial measurement is a distant memory, one of the last standards to change will be the 1/2 inch pitch bicycle chain. Because, so far even the French have not been able to get around that one.   


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Reader Comments (20)

A very entertaining and informative overview of units! I'm especially amused by the mixed units (36 mm BB diameter with 24 threads per inch, etc).

July 29, 2015 | Unregistered CommenterLee in Seattle

I recall reading, maybe it was a USENET posting by Sheldon Brown, the reason for the mix of metric and imperial measures on Italian bottom brackets.

The Italians used lathes with imperial lead-screws rather than metric. They could turn stock down to any arbitrary diameter, but the thread cutting gears were already rigged for cutting threads-per-inch rather than threads-per-millimeter.

July 29, 2015 | Unregistered CommenterJohn Thurston

I feel your pain :-) I grew up in Canada, which officially went metric in the early 1980s. Before that we used the English Imperial system (and don't forget US liquid measurements are unique and unknown anywhere else). When I studied physics, I had to be able to do both metric and Imperial calculations. And there are even flavours of metric - some countries only use millimetres and meters and never use centimeters (although the conversion, as pointed out, is pretty simple.)

I moved to the USA in the 1990s and worked for a high-tech manufacturer. Every single measurement on our $2 million machines was done in metric. Every machine shop worked in metric. 100%. At the very end, if the customer was also American, we converted all the metric measurements we could back to US for the manuals. Obviously thread sizes, etc. stayed metric - just like bicycles.

Contracts for work on the US Interstate system are always done in metric.

When I moved from the USA to the UK in 1999, I took my US motorcycle with me. I moved from a country with a "miles per hour" speedometer to the only other country in the world with miles (and still does). I had to have the motorcycle inspected before it was legal and the inspector said "Hey - how about that?"

When I worked in Ireland in the 1990s, I would see signs "Kinsale 10", then a while later - "Kinsale 12". Am I going the wrong way, I wondered? Nope - old signs in miles, new signs in kilometers. The locals knew. Like they needed signs?

The only reason for inches is history. The metric system works wonderfully. But every car in the world rides on tires in inch sizes. Or is that tyres?

July 29, 2015 | Unregistered CommenterSteveP

If the 1/2 pitch bicycle chain was changed to metric world wide, then every bicycle would become obsolete when the chain wore out. In the same way if they changed tire sizes to metric, car wheels world wide would become obsolete. So I guess that is why these items stay the same. Too much trouble and expense to change.

July 29, 2015 | Registered CommenterDave Moulton

Same can be said for measuring temperatures in centigrade or Fahrenheit. Britain uses the former and America the latter. I do both; centigrade in Winter (freezing at zero seems to make more sense to me) and Fahrenheit in summer; 80 degrees feels more like Summer than 25. 😊.

July 29, 2015 | Unregistered CommenterJW

Whoever said nothing is sacred is wrong. Literally everything in the bicycle drivetrain has changed and become incompatible, all the way down to the bottom bracket and hubs.

But don't you dare touch that half-inch pitch between the rollers…

July 29, 2015 | Unregistered CommenterChamps

It was a source of both amazement and amusement when I moved here from the UK in 1994 to find that the USA was even further behind in the adoption of the metric system than my home country, However, I have to admit that I have a scientific background, and was therefore ahead of most of my British compatriots in grasp and use of the metric system. The worldwide scientific community embraced the metric system in 1949, as far as I remember.
My last job in the UK was in hard cider production, and my first here in California was at a winery. It was like stepping back in time to find that Napa wineries were working in gallons, and making additions to wine tanks in lbs/1.000 gallons. (even worse, is the practice of mixing the two systems which I have also seen, e.g, additions in kg/1,000 gallons.) This is still the case now.
Ironically for a Brit, I became the metric expert at the winery, and the owner would check with me for unit conversions.
In my opinion the only thing that needs to be left alone is the English 20 oz pint of beer. That one is sacred. I consider myself cheated by each 16 oz "pint" here!

July 30, 2015 | Unregistered CommenterMartin W

This post has reminded me I left school at age 16 in 1952. I began a 5 year Engineering Apprenticeship with SKF a Swedish Ball Bearing Manufacturer. They built all their own special purpose machinery, and everything was metric. Micrometers and dial indicators were calibrated to measure 100th of a millimeter. all engineering drawings were metric. I soon realized, for example, how simple it was to convert mm. to cm. by simply moving a decimal point. Being well versed in Imperial and metric has served me well throughout my life.

July 30, 2015 | Registered CommenterDave Moulton

SteveP - how difficult was it to convert your motorcycle to drive on the left side of the road when you moved to England? : )

July 30, 2015 | Unregistered Commenter82medici

As an ex-pat I was caught totally unawares by the 1971 switch to decimal currency.
I grew up with quids, bobs and tanners. On my first post-switch UK trip I felt very much a tourist as I fumbled with the new notes and coins, some of which were the old ones but with a new value.

July 30, 2015 | Unregistered CommenterAnthony C.

Being also Canadian, I can appreciate everything SteveP said. But Canada is unique in that we still measure building materials (except roof shingles) in feet and inches. We also got gypped when they went from miles to kilometres because speed limits got marginally lowered and have stayed there for 40 years. One promise was that weights and packaging would be standardized with the switch, but it didn't really happen with grams to play with, so deceptive packaging only got worse.

But getting back to bicycles. I remember inch size frames being measured to the top of the seat lug, while metric is centre to centre. Dave, didn't you keep measuring to the top of the seat lug when you went metric?

July 30, 2015 | Unregistered Commenterjohnb

Nobody told me about the center to top, center to center thing so I never switched. by the time I realized I had already sold a lot of frames and it would cause more confusion by switching. But it is why I measure to an imaginary line just above the seat lug, it makes it an even 2 cm. less center to center.

82medici coments about SteveP converting his motorcycle to drive on the left. With a motorcycle or bicycle it is only the handlebars that are on the wrong side, so it is an easy switch. You're welcome.

July 30, 2015 | Registered CommenterDave Moulton

Hi Dave,
My "two cents" here in southern Arizona Interstate 19 that runs from Tucson south to Nogales and eventually into Mexico the distance signs are in kilometres
( the only one in the US I've been told) yet the speed limits are in Miles Per Hour (MPH) just like the rest of the USA. I used to make micro carbide tools on Swiss Ewag grinders that were retrofitted with digital DRO's that had either type of measurement. Initially when I started I had prints in inches and millimetres and would convert all the metric to inches ( because that was how I was taught). My co-worker was from South America and she was a math teacher before she immigrated to the US. She made all her tools using the metric and converted her inch prints the metric. One day she suggested I try using the metric system because everything was based on the number ten. I can't tell you how much easier it was to use ! I still use both because each has it's merits.

July 30, 2015 | Unregistered CommenterBrian

Here in Argentina every thing is metric, but tire pressure is mostly measured in psi and lumber comes in Imperial sizes.
I think Shimano tried a new 10mm chain pitch standard sometime, but it didn't succeed.

July 30, 2015 | Unregistered CommenterLuis

I have lived in a number of countries in my life and have had to get use to all the various units including currency. One of the good characteristics of humans is their ability to adapt.... if they want to!
in the mid '70's, my Thermodynamics teacher wrote his own text book that he used our class to proof read and validate as a text book. All in metric units. I still have a hard time relating to BTU's!

July 31, 2015 | Unregistered CommenterSJX426

Partly it's what you grow up with. I grew up in England with Pounds, Shillings and Pence, even farthings. It all made sense. In Canada I had no trouble adopting dollars and cents, which made even more sense. My mother used a Celsius thermometer and we had to stay in bed if it went over 37. I never did adapt to Fahrenheit body temperature. No trouble with F or C air temperature, but I know lots of people who set their home temperature in Fahrenheit.

But back to bikes again. I will never think of gears in anything but inches or tire pressures in anything but PSI. Everything else is gibberish to me.

July 31, 2015 | Unregistered Commenterjohnb

Inevitable but another political hot potato. Progress on issues like this brings out the anti-American rebuke.

"What is it with these big-government liberals?"

"Chaffee doesn’t really want to bother with topics like the national debt, crappy public schools, the breakdown of the family, a gargantuan, complicated tax code, energy independence, border security, or any of that. No, no, he’s going to save us from inches, gallons, and miles."


July 31, 2015 | Unregistered CommenterJack

Here in the UK the railways still use today the 'chain' length to measure distance, and the distance of miles and chain lengths is included on railway distance markers for bridges and stations. My railway station has a sign advising "23m 14ch". i.e. 23 miles and 14 chain lengths outside of Waterloo.

Incidentally, one chain length (22 yards) is also the length of a cricket pitch, although it is never referred to as such in today's cricket world.

July 31, 2015 | Unregistered CommenterDavid Gibson

Being an Australian born in 1971 I have always used the metric system. As a teen I spent some time in the US and to this day I cant understand their need to use such an antiquated system of measure.

One of my early jobs was as a surveyors "Chainman".

The chain was a commonly used measure in the imperial world of surveying. As stated one chain was 22 yards. Which is 66 feet. Funnily enough though it is divided into 100 links. Another hint to the ease of using tens is that there are 10 chains in a furlong. But 80 chains make a mile. However in a bow to simplicity an acre is the area of 10 square chains :)

July 31, 2015 | Unregistered Commentersss

I'm confused. I have an American made bike with an Italian name, built by a gentleman who was born in England. Does the bike have a chain pitch of 12.52mm or 1/2"?

Take a look at carpenters. They must be good at math. They routinely work out their measurements in base 10, base 12, and base 16. For example,: 8' 4 and 3/16".

To JW, I'm just the opposite. Stuck in Texas, an August temperature of 40* (C) just sounds so much better than 105* (F).

August 4, 2015 | Unregistered CommenterJim
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