Both approaches have coexisted and still coexist because the results render data that are easy to interpret---as long as you stick to the approach you're used to. A case can be made that Celsius is relatable to the freezing and boiling of water and that the Fahrenheit system is archaically arbitrary, but for me, having grown up with Fahrenheit numbers, understanding what a Celsius temperature value represents still requires a laborious mental conversion to Fahrenheit.

If you quickily want every possible combination of gears in the range your considering, this calculator gives results in multiple formats, including the actually useful speed per rpm:
https://www.bikecalc.com/gear_inches

But this one is really cool, because it populates with realistic equipment inputs and presents the results in a chart designed to make comparing easy. It has pull downs that capture factory cassette combinations rather than giving you every possibility in a range. And it has a compare button if you want to look at how two very different bikes are geared, or what changing your chainrings would accomplish. Displays results in development, speed, etc. But you can just note the relative locations of the ratios.
https://www.gear-calculator.com/

Screw doing math.

Gear inches was…and is…a way to compare gears. Originally it was the way that ordinaries (penny farthing, big wheel bikes, etc) were sized. Your leg length determined how big a wheel you could ride. A 60” to 65” bike was about average. It’s about twice the average leg length (30” to 32”) and when the crank goes through the axle of the bike, it’s the limit that bicycles could be comfortably be ridden. Once safety cycles came into being where the wheel size wasn’t the determining factor, gear ratios were used. Since people were used to wheel size for which bike they could ride, the ratio of the chainring to the rear gear multiplied by the diameter of the smaller wheel became a convenient comparison.

Many of us still use it for comparison of gearing. Simply using the ratio would work or using distance development would work. Personally I find gear inches to be easier to wrap my head around. Gear ratios seem too small and distance development seems too large. I only really use gear inches for setting up the drivetrain. I find it a useful tool for comparison but out on the road they are of no use. I know (kinda) which gear I’m in and which way to shift to make the pedaling easier or harder but I don’t think about gear inches out in the field.

For the purpose of comparing gear ratios combined with tire size, both development and gear-inches are usable metrics. However, I've seen quite a few people confuse these two terms largely because gear-inches is a stupid concept in the modern era. Development relates directly to the action of riding a bicycle - turn the pedals, travel X distance. I have a strong opinion about gear-inches. I don't need anyone to agree with me.

You can use any system you like. Yes, gear inches is kind of dumb but it is more commonly used than ratios or development. Most of us are used to using gear inches so when we talk to others about gearing, we get a whole lot fewer blank stares than if we start talking ratios or feet (meters) development. In my life, I’d much prefer to use the metric system and a 24 hour clock but here in ‘Merica! if I say I need a board 50mm x 200mm x 2.4m long, I might as well be asking in Russian.

For comparing bikes of the same wheel size or comparing what might be with different gearing on the same bike, ratios work well enough.

And you have to sit down and calculate all of them.

Your points are valid, and I've used gear inches for decades because that's the generally-accepted standard among bike folks. That doesn't change my opinion. I have similar opinions about the term "clipless" - LOL. I understand how and why these terms came to be.

You do? I can operate the calculator function on my phone while standing up! :p

Oh, did the rental place repossess your couch?

Wait til you have to consider 'dialing' a phone number.

Sorry, a little confusing. I don't carry gear charts to work out possibilities as I ride. I have been know to print out small plots to tape to my stem for new triple setups although I haven't done that in years.

wtf??

This thread has had me thinking more of development. I've known of it a long time. It is the key number for any junior racer. Also called roll out. Done physically with the bike. Start with the crank down at the beginning line on the floor or pavement. Pedal until the crank comes down again. Bike better not have crossed the second line!

But for me. Development is the easy number to calculate that significant sum on a fix gear ride - pedal revolutions. Revs per mile and total revs have always fascinated me but the in-head on-the-bike math gets tedious. But my 42-17 gear giving me 17.5' development? 5280 / 17.5 is doable. 302 pedal strokes per mile. I like! (Same gear; 67", 100 RPM gives 20 MPH. The basis of much of my rolling gear chart and speed/RPM math. Edit: Just put a new tool in my bike math basket.

And why do math in my head on the bike? Well, it's fun and it's a "use it or lose it" activity, just like riding (for me).

That was uncalled for. kontact, this isn't P & R. Just gear charts. Let's keep it civil.

Depends on how good you are at simple math in your head. The only thing involved for gear ratio is the front number of teeth divided by the rear number of teeth.

Once that is straight in ones head then simple relational assumptions can be made that don't require doing math or using online calculators.

Bigger tooth count on front, harder to push the same cog on the rear. Bigger tooth count on the rear, easier to push with the same ring on the front.

Go with Mario Cipollini's Pamela Anderson pro setup (to "boost testosterone," said Mario):

https://i2-prod.dailystar.co.uk/inco...-989416628.jpg

I'm very happy for you.

Or sorry to hear.

I'm not reading all that.

The bigness of a wheel has three dimensions, radius, diameter, and circumference. We're talking about diameter.

I remember a cute girl in my freshman chemistry class, who rode a lovely light blue Mercier, with a gear inches chart on a shrink-wrapped 3x5 index card hanging from the handlebar. A little OCD she was.

I can't remember a single time when I have had the urge to calculate gear ratios, gear-inches, or development while in the process of riding - LOL. Then again, my relationship with math is pretty mediocre.

Eric made a joke about my post, I made a joke about his. Nothing bad happened.

This is exactly why The Columbia space shuttle exploded on the moon a few years ago.

Ratios are a totally dumb concept. 3.3 of what?? Who the hell knows?? NOBODY.
Gear inches relate very nicely to steps walking/ running. 17" is a baby step and 100" is The Lightning Bolt running the 100m. LOL.
And I just thought of an oddball comparison. GIs are quite close to degrees F. 16 is frigid cold and 120 is scorching. 70 is room temp/ flatland riding.
As for riding on the highway, all you need to think about is 15 mph is 4 minutes and 20 mph is 3 minutes.
Cadence has basically zero to do with distance if you coast 10 to 20% of every rev, like most people do.

Actually, Columbia blew up on re- entry to Earth. The cause was more about bad glue than bad math.

I think you're referring to the Mars orbiter which was lost because of a Metric/imperial data mismatch.