Newb Torque Wrench Question
 

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What's the 3/8 drive vs. 1/4 drive. What does that mean? What's the difference?

Yeah yeah yeah....I'm a big n00b.

I believe that has to do with the head of the wrench. FOr instance a head with a 1/4 drive fits a socket with a square cut out of 1/4.

Phantom is right. That is the size of the square hole on the socket that the wrench fits into.

This is why I'm sure our country has never been serious about going metric. The back side of all sockets, even the metric ones, have a square drive hole that is in fractional inches.

The country has never and likely will not be in our lifetimes.

The trick is whether or not a Metric measurement is something you can "picture" without converting it first.

For example, do you have an idea of how big a 59cm seat tube is? Congratulations ;)

On the surface it refers to the socket drive size, but it has a deeper meaning especially for torque wrenches. Components like crank bolts and bottom brackets usually require around 30 or 35 lb/ft of torque. Imagine a 30 pound weight on the end of a foot long wrench handle. That requires a medium hefty wrench with a 3/8" drive. Components like stems require around 12 lb/in of torque. That usually involves smaller fasteners that work better with a smaller 1/4" drive.

Can you use one torque wrench for both? Kinda, but it's pointless. To get an accurate torque reading, you need to use a torque wrench that includes your desired torque setting near the center of it's range. A 3/8" torque wrench won't be very accurate at 1 lb/ft of torque for installing a stem. It it's not going to be accurate, what's the point?

if you grow up with its not an issue...
I cant picture what 24" looks like.

Im gonna refrain from making anymore comments about the how the US system makes "sense".

The metric system is easy, once you get the hang of it. But speed is a big ripoff. To see 120 (Km) on your speedo, and be going so slow. No fun.

So what size engine does your car have? Bought any prescriptions lately? How about a bottle of booze? It's happening.

I have a friend who bought some tulip bulbs from Holland. He planted them 24" deep or whatever he thought it said on the package. Seemed awful deep at the time. HELLO! Holland, like everybody but us is a metric country. 24" is 24 millimeters, about 1 inch not a whole foot. Surpriseingly, most of the bulbs eventually came up anyway, but they were late.

actaully what's funny in canada is everything is metric except the height and weight of a person. So i know how tall 6' is and how much 200 pounds is. But ask me how far a mile is and im screwed.

200 pounds. That's 10 stone, right?

Bicycles are not truly metric either. Steer tubes are 1 inch or 1 1/8 inch. Chains are one inch per link (1/2 inch pin to pin), and those are worldwide standards.

Al

Most everything I need to torque on my bike is in inch/lbs. The torque wrenches themselves were all roughly the same price, but I went with 3/8 as that size had the widest variety of sockets in stock.

Torque wrenches are like peanuts and potato chips, you can't have just one.