American Customary (a.k.a Freedom) Units vs Imperial vs Metric

[jabberwocky]

As a pro architect and hobby woodworker, I prefer imperial units. Aside from just being used to them, base 12 divides in half, thirds and quarters evenly, which are extremely common operations in design at both building and furniture scales. Base 10 divides in half and fifths and thats it. Most materials I deal with are imperial in the US, with some exceptions (like baltic birch plywood is generally metric thickness so what is sold as 1/2" is actually 12mm so a bit thinner).

Aside from that, eh. I'm reasonably good at mentally converting most common units. I model stuff in cad for 3d printing pretty regularly and most 3d printing software is metric so I either have to design in metric or scale it when I go to print. My shop has a full set of wrenches/allen keys in both imperial and metric and I run into both. Most bike hardware is metric. Shop tools are a mix (modern imported tools tend to use metric fasteners, older tools are more commonly imperial, but you find both everywhere).

I just remember that 1in is 25.4mm, 100km is 62 miles, 1kg is 2.2lb and I can mostly work backwards to convert things in my head and be reasonably close when I need to.

 

[jabberwocky]

On last Saturday, my mate Krzysiek was to replace the inner tube in his vintage bike. I wanted to help him with any tools I had with me. No chance! He needed a 15 mm wrench (and it got stuck inside his frame storage). He didn't use Presta valves but Schrader. He had to be self-sufficient!

Way back when I used to commute on a fixie, the cheap bolt on hubs my older bike had used 15mm nuts. Super common on bolt on track hubs in the US and Japan. I kept a shorty 15mm wrench from Sears in my saddlebag as a solution. Eventually put Phil Wood hubs on that bike which used an allen instead (still metric, but a size that most bike multi tools had).

 

[Stefan Mikes]

@jabberwocky: Before the hard times of nowadays, I bought Mirrycle mirrors for several times. As long as the product came from Amazon, all sockets were hex 3 mm despite Mirrycle is an American product. Once, I bought a Mirrycle from a strange seller in Germany. That crook sent me a mirror with imperial sockets! Yes, there was an appropriate hex key in the package. Once that little key was lost... (My brother keeps the mirror, he has got all tools).

 

[jabberwocky]

Bike hardware is almost entirely metric, even in the US. I assume its just because bikes historically were made in Europe so European sizing mostly drove the bus for standards. But there are weird exceptions. Pedal wrenches are generally 9/16". Bike chains are 1/2" pitch. Handlebar clamps are measured in metric but convert to standard imperial (standard 25.4mm is 1in, oversized 31.8mm is 1.25", etc). MTB tires are generally described using imperial (i.e. 2.4" wide) while road/gravel uses metric for widths. I think being a bike mechanic is probably a good way to develop mental flexibility when it comes to units.

 

[Stefan Mikes]

The bicycle was a British invention