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Home » Cycling » The Noob’s Guide to Cycling: Understanding Chainrings – the Road Bike’s Front Gears, How and Why.

The Noob’s Guide to Cycling: Understanding Chainrings – the Road Bike’s Front Gears, How and Why.

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In cycling, understanding, really getting into, the front gears, or chainrings, is a bit more complex than simply “buy a bike and whatever happens to be on it, go”. In fact, the front gears are just as important as the back gears and can be tailored to match your riding conditions or even your riding style. In this post I’ll cover the triple, the pro double, the pro compact and the compact set-up.

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The triple was once common because it was magical when things got uppity. It’s also the most finicky of the cranksets available on a bike – getting one dialed in properly can be a lesson in patience. For the triple, you’ve got the big ring (52 or 53 teeth), the middle ring (39 or 42 teeth) and the baby ring (24 to 30 teeth). The pro double, once the staple of pro rigs, consisted of a 52 or 53 tooth big ring and a 39 or 42 tooth small ring. The pro compact, new as of 2012 or 2013, is 52/36. The compact crank is 50/34.

Now, back in the day of 5, 6 and 7 speed cassettes, getting a full range for going fast on flat ground and climbing steep hills could be a little tricky – thus the use of the triple crankset. The triple gave you all of the gears of a standard pro double (52/42 or 53/39) plus the baby ring (24 to 30 tooth) for climbing. Going up an 18% hill in a 42/23 (front to back) combination was ugly. With the triple, all of a sudden hills that would baffle many enthusiasts became accessible.

With the advent of the ten, eleven, and now twelve speed transmissions, the third chainring is becoming obsolete because there are so many bigger gears available on the cassette, the triple isn’t necessary anymore.

That said, where triples will always be invaluable is on a tandem.

Now, with that out of the way, let’s get to the fun part! The coolest thing about chainring combos is tailoring them to your needs. First, if you need to know your recommended crank length, go here and input the pertinent info… Next, if you’re like everyone else, you’ll just live with what you’ve got, so let’s move on.

Let’s say you’ve got reason to install a new crank on your bike, or you’re replacing worn chainrings. Most will just go ahead and get the exact replacements for what they’ve already got on the bike, but let’s think this through a minute. What is your riding style? How about top speed? What’s your normal terrain, flat as a pancake or hilly? How about your average pace? North of 18-mph or south? All of that info will factor into your chainring selection.

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For instance, if your average pace is 16-mph, the last thing you’ll want is a 52/36 or 53/39 as you’ll spend most of your ride in the little ring – 52/25 or 26 (the second to the last gear on your cassette is only good for 15 or 16 mph… or the last gear on your cassette that you can use with the big ring because you don’t cross chain the drivetrain). No, a 50/34 would be a much better fit as you’ll have three more gears to play with when you’re riding in the big ring. With a top-end of around 37-mph (50/11), you’ll have more than enough gear to keep up on the downhill sections.

Say you’re a stronger cyclist, able to hang with the 20-mph + crowd. You’re an enthusiast, certainly, but you’re more recreational than a racer and you like to get into some hills now and again (this describes me, by the way). Well, in that case the 52/36 was made specifically for you. You get all of the top-end speed out of the Big Dog, but you get a decent baby ring for when things take a turn for the up. I’ve had my Venge (pictured above with the aluminum colored chainrings) on inclines above 20% and I was able to crank out more than a few feet with the pro compact crank.

Aspirations on being a racer? 53/39 all the way. Enjoy horsing that big bitch up an 18%’er though. Serious racer? 52/42. Peter Sagan? 55/42. What a beast! I’d be willing to bet he goes with the 52/36 on his Tarmac, though (his climbing bike… the 55/42 is for the flatter stages… nope – 53/39… what a feakin’ animal!).

Anyway, you get the idea. Why settle for what comes on the bike when, with a little thought, you can have a drivetrain that fits your needs?

In my case, I have a 52/36 combo on my Specialized, because A) that’s what I wanted because you can’t have a race bike with a compact crank on it at my age, B) it suits my riding style and pace perfectly, and C) well, it came on the bike. The Trek was a different story entirely. I put some serious thought into what I wanted on that bike. First, it’s my rain bike, but more important, that’s the bike I take out on tours because it’s so easy to work on if I have a problem – and now with the new Ultegra bottom bracket and Shimano RS500 crank, it’s better than anything I’ve ever worked on. It’s actually simple.

I thought about what I was going to need that bike for. I encounter a lot of hills when I travel, so score one for the 50/34. I like to climb hills when I travel, so that’s two. The tours I do, specifically Northwest and DALMAC, both have a fair bit of climbing… score three. They also don’t have a lot of top-speed descending, and the guys I ride with really don’t push max-speed anyway, so I won’t have a problem keeping up. In other words, the compact makes a lot of sense on the bike, all things considered. After a couple of weeks on it, I couldn’t be happier with the decision.

The point is, don’t settle. Make your bike yours, you’ll appreciate it more. That’s the way it works for me.

This is a companion piece to this post.

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5 Comments

  1. 925brands says:

    Keep sharing, stay motivated…

  2. MJ Ray says:

    “The pro compact, new as of 2012 or 2013, is 52/36.” Cool. My Falcon was 30 years ahead of its time! 😉

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