I finally know what the numbers mean.

Don’t worry: I have not been obsessing over a set of numbers like the incomparable and endearing but somewhat psychologically addled Hurley on “Lost,” but I have finally satisfied my curiosity as to what numbers such as 50/34, 12-25 and 11-27 mean.

Those who are knowledgeable about bike gearing already know what I am talking about, but I would guess a fair number of riders — perhaps even regular cyclists — do not.

To begin, let me back up a bit. I started competing in triathlons four years ago. I came from a running and swimming background and knew almost nothing about cycling except for how to ride a bike.

Like many participants who are new to their sport, I was interested in expanding my knowledge base. For me, that extended to cycling in particular, given my lack of expertise in that sport.

Perusing bike-related forums, I would read terms such as “compact crank” and some of the numbers listed above. The posters would use them in reference to bike gearing but would not explain what they meant in ways that made sense to a beginner — at least not this beginner. As I invariably seem to forget to ask the questions I would really like to have answered in places suitable to that end — such as my local bike shop — I was invariably kept in the dark until I decided to finally investigate in the past couple weeks.

As far as gearing goes, I have had the basics down for quite a while. I understand that riding with my chain in my small chainring (the rings with all the teeth at the front of the drivetrain are your chainrings) is easier than riding with my chain in the big chainring. I also understand that within each chainring, riding with the chain on a bigger cog in the back is easier than riding on a smaller cog (the rings with the teeth in the back, at the hub of the rear wheel, are called cogs; collectively, the cogs make up a cassette).

But that was as much as I knew. Until a few days ago, I did not know what kind of crankset or cassette was on my bike, if it was the right one for me, or if I would be better off with something else.

So I went looking for answers.

As both Susan Bonacker at Sunnyside Sports and James Gritters at Sagebrush Cycles explained to me, the numbers such as 50/34 refer to the number of teeth on each of the chainrings. And numbers such as 11-27 and 12-25 refer to the number of teeth on the smallest and largest cogs in a cassette, respectively.

But the teeth on those chainrings can vary. Something called a compact double crankset has become common in the past five years, Bonacker said, noting that a “compact” has a 50/34 chainring combo on. The most common pairing for a standard crankset, Gritters said, is a 53/39.

Just how common is a compact crankset these days? Bonacker said that all of the bikes on the Sunnyside floor have compact cranks, and Gritters estimated that 90 percent of bikes in general sport the compact.

“So now everything in the back end is lower,” Bonacker explained, referring to the gears. “However, you have this 11-tooth cog back there that compensates for that because it’s a higher gear for your back. So what you end up with is gears that you use more of — and that’s the take home. A compact crank will give you a big chainring that you can use not just on that one time when you’re riding down Mount Bachelor. It’s a chainring that you use all the time on the flats.”

A compact double, Bonacker added, offers a wide range of gears, spanning from a low climbing gear to nearly as high of a big gear as a standard crankset.

Those lower gears can be helpful, such as when climbing big hills.

“Everybody wants to use the easiest possible gear to get up the hills,” Gritters said.

While many cyclists are riding with the compact cranks these days, some riders may still prefer a standard crankset. Gritters said that riders who are long accustomed to a standard crank and most racers still opt for it.

As for the cassettes, going back to those numbers, a 12-25 cassette’s smallest cog has 12 teeth, its largest has 25, and the other cogs have numbers of teeth falling somewhere in between. And the larger the cog, the easier the gear. Some cassettes offer wider gearing options, Gritters said, with 11-28, 12-30 (new this year) and 11-32 cassettes being popular.

Thoroughly curious as to what type of crankset I had on my bike after these conversations, I brought it to Sunnyside Sports for some analysis. As it turns out, I have a standard crankset (that is a 53/39 chainring combo) and what looked to Sunnyside employee Muffy Roy like a 12-25 cassette. If I were to purchase my bike today, she noted, it would probably come with compact crank (that 50/34 combo) and an 11-27 or 11-28 cassette.

But that does not mean what is on my bike is bad or does not work.

“If you ride it and you enjoy it, and you find that you can sit in the saddle climbing as much as you like, then it’s fine,” Roy noted.

Overall, I feel like I am fine with what is on my bike. I have ridden only with a standard crankset, so I do not know any different, though I would be somewhat interested in how a compact crank would feel. But if I were to change my gearing, a different cassette might be helpful. I do not find that I need a bigger gear at the top end, but sometimes I find myself thinking that another gear or two at the lowest end might be a nice option for steep pitches.

Changing out a cassette is a “cost-effective, simple fix,” Bonacker said, with viable options running between $30 and $200. And decent cranksets are available for $150 to $200, Gritters said. But you do have to swap out the entire crankset, as compact double and standard cranksets use different-size bolts.

In the end, I do not know if I will wind up changing anything. But if nothing else, I do feel like a more educated cyclist.

After all, now I know what the numbers mean.