Gearing Part 1: What are they and why would you change them?

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In this quick, 2 part series we’re going to look at the gearing on your bike and how changing it can have an impact on your riding. While we all know where the gears are on our bike most will struggle to identify what they are or how changing them might affect your riding.

Gearing is always a popular question leading into a race. Unfortunately there isn’t always an easy answer for an athlete. The best that we can do as coaches is determine what the goal of the ride is going to be and how the course is going to impact that goal.

Lets first talk about what options are out there to outfit your bike. There are 3 main pairings for your chainrings (the gears in the front); 50×34 (compact), 52×36 (mid-compact), and 53×39 (standard). The numbers simply refer to the number of teeth on each of these rings. With these gears a higher number of teeth will yield a higher speed. These gears are your macro changes when riding.

The gears on the back or cogs, are collectively called the cassette, have more variety in their sizes and are much easier to replace. On a normal road wheel you can have a low tooth count of 11 and a high tooth count of 36. Cassettes will be labeled according to their outer tooth counts. So a cassette with a small cog with 11 teeth and a large cog with 25 teeth would be referred to as 11-25. On the back wheel fewer teeth will yield a higher speed. These gears are your micro changes when riding.

When I’m trying to determine the correct gearing for an athlete I will generally ask what their average speed is during their race, but this doesn’t always work because they may not have done a race that distance yet, or the topography of the course may be completely different from what they have ridden in the past. However, I will generally use these ranges when trying to determine chainring sizes. Keep in mind that these would be the average speed for the rider’s race distance.

>22 mph

Standard (53/39)

18-21 mph

Mid-Compact (52/36)

<17 mph

Compact (50/34)

While some riders will look at the gear sizes and get discouraged about being faster or slower, it would be foolish to take this point of view. The goal of different gearing sizes is to allow you to keep your cycling cadence in your optimal range while riding. The speed you’re riding at is simply the result of your effort. Putting yourself in a situation where you’re unable to ride at your desired cadence can create a myriad of problems, most of which result in a suboptimal performance.

A hilly course is a cause for concern for many cyclists and will be an exception to the average speed/chainring size ranges. A certain amount of experimentation is necessary to determine exactly what is going to work for an individual rider. Rider weight, FTP, hill duration, and the race distance will all play into what speed can (or should) be maintained on a hill. As with most changes, use baby steps. If you’re riding a standard crank, but struggle on the hills, it may not be best to switch straight to a compact crank. However, if you’re an ironman athlete and are heading into the mountains to do your race, switching to a compact crank will likely allow you to keep your power from spiking and keep you from riding above your target for an extended period of time.

While a flat course usually fills riders with hopes for PR bike splits, bike splits are only a portion of our triathlon journey. Wind is a constant companion to the flat bike course, and wind can do as much damage as hills when it comes to time and energy spent out on the course. Again, experience and experimentation are the key here to determining what gearing to run.

The next article about gearing will dive into the new phenomenon of the 1x (one by) drivetrain with explanations as to what it means and how you might set yours up.

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