Exactly. I'm glad we helped. Development, also called rollout, makes more sense, but we just don't do that in the US. Either development or gear inches are good measures because they are independent of wheel size. I've used gear inches all my life, so in my mind, there is a scale of 25 to 130. A 25" gear means I can climb any slope while carrying cargo. A 130" gear is useful if I'm going very fast down a steep, long hill and I want to add even a little more speed. Most people are comfortable cruising on flat ground in a 70" gear. If you have a single speed bike and live in a flat area, you'll probably want your gear to have 70".

It might help to convert these numbers into development distances if you want to think of it that way, but to compare your gearing to someone else's, you may have to speak their language. You might ask a friend, "What gear did you use to climb that hill?" They might say 40 inches. Does that make sense to you? They might instead say 42/28, and if you both have 700c wheels it makes sense, as it's a 40" gear. But I don't like the tooth count measuring method because it relies on the wheel size for it to be uniform. Besides, as I pointed out, it's hard enough to calculate gear ratios in your head, it's even harder to remember which ratios are equivalent. 42/28 is nearly the same as 52/34, but who remembers that? So when someone says he climbed a hill in his 42/24 gear, I ask what that is in gear inches.