Understanding How The Gears on Your Bike Work

An overview for triathletes on how gears on your bike work and tips to maximize your efficiency and performance.

How do gears on a bike work

A human being on it’s own two legs is one of the most inefficient moving animals on the planet. Put that same human on a bicycle and they leapfrog evolution to become the most efficient animal on the planet. Add gears to that bike and an understanding of how gears on your bike work, that efficiency is increased exponentially. 

Bicycle drivetrains first started including gears in the late 1800’s. These were heavy, mechanical set ups that are a far cry from wireless/electronic systems we use today. However the outcome was the same, gears allowed riders to adjust ratios so they could maintain the same level of power and cadence regardless of gradient. 

How Do Gears on Your Bike Work? 

There are typically 2 sets of gears on the average road bike or triathlon bike, the chain ring (gears connected to the pedals) and the Cassette (gears connected to your back wheel). 

In the front, the chainring, the larger most outside gear will be harder while your smallest or most inside gear will be easier. On the back wheel, the cassette is the opposite. The largest most inside gear is the easiest while the smallest and most outside gear is the hardest. 

Shifting through each of these changes the ratio and force pushed from the pedals to the wheel. 

What Role does Cadence Play?

Cadence is the number of rotations your pedals do a complete 360 degrees in one minute. The ideal cadence can vary person to person but generally falls into the 70 – 90 rpm range. 

While riding, the general goal is to keep cadence as consistent as possible throughout a ride. Adjusting your gearing allows you to dial the resistance up or down so that you can do so.  A person’s ideal cadence is where they achieve the highest level of energy efficiency which is why we strive to maintain it. 

There are some scenarios where your cadence may vary such as aggressive climbing, sprinting, fast descents or riding into strong headwinds. However this adjustment is in small increments and gearing is what allows you to do so. Shifting to the next smaller gear on the cassette will increase the resistance on the pedals and allow you to slow your cadence slightly and vice versa. Much of this will depend on the course you’ve selected to ride

Anticipate the Road Ahead

The best riders will tell you that success is all about being one step ahead. Adjusting your gears is something that should be done proactively not reactively whenever possible. This means anticipating changes in the road ahead. 

If riding a flat road in the big chainring up front and you see a hill coming up, proactively change your gears to prepare for the climb. This means lowering the front chainring gear and increasing the rear cassette gear to match your current effort. This will then allow you to easily decrease the rear cassette gear as the incline of the road increases. 

In another scenario, if you know you have a sharp turn coming up that you’ll need to slow or even stop for, lower your gearing before entering the turn so that you can start pedaling out more easily. 

Bike Gearing Mistakes to Avoid

Cross chaining: When you are in the opposite extremes of your gears, meaning highest (most outside)  in the front and lowest (most inside) in the rear and vice versa. This is not only a less efficient set up, but it also puts the most strain on your components and should be avoided if possible. 

Grinding your gears: Pedaling in a gear that is too hard for the terrain you are on, forcing you to exert excessive power at a much lower cadence. This is the most inefficient format for a cyclist. If you find yourself in this situation, lower the rear gear (Cassette) one at a time until you find a comfortable cadence. If the lowest gear is still to hard, shift the front (chainring) to the smaller gear to relieve even more pressure. 

Mashing your gears: Changing a gear while putting a high force on the pedals. The result is the chain slamming into the next gear, often creating a loud “THUD”. This is not good for your components and will cause them to wear out faster. To avoid, briefly lighten up on your force to the pedals as you shift, this will allow your gears to change more smoothly.