Your guide to what the heck everyone is talking about. Triathlon has its own language.
Your guide to what the heck everyone is talking about.
Triathlon has its own language. And if you’re new to the sport, you’ve probably heard someone say something like “I hit a PR in my 70.3 thanks to my new bike-fitting and aero setup” and thought… what?
Don’t worry. Here is your unofficial, unfiltered, alphabetically organized triathlon dictionary. Let’s go.
Aero / Aero Position
Aero means aerodynamic, reducing drag so you can ride faster using less energy. Aero position is when you’re tucked low over your handlebars, often using tri bars or clip-ons. It’s fast. It’s not always comfy. It takes practice.
Age Grouper
Unless you’re a pro, you’re racing in an age group. You’ll be grouped with people your age (like 30–34 or 40–44) for fair competition. It’s also how a lot of people qualify for big races like Kona.
Aquathlon
A race that includes a swim and a run. That’s it. No bike. Perfect if you don’t love cycling or want to mix things up.
Australian Exit
In some open water swims, you’ll get out of the water, run around a marker on land, and then jump back in for another swim lap. It’s chaotic. It’s fun. It’s very spectator-friendly.
Bike Fitting
This is when a professional adjusts your bike to fit you. It’s all about comfort, efficiency, and injury prevention. A good fit can make a huge difference in how you feel on long rides. If you’re riding more than a few hours a week or training for a race, it’s 100 percent worth it.
Brick Session
When you do two disciplines back to back, usually bike then run. It’s how you train your legs to handle that weird jelly feeling after cycling.
Cadence / RPM
How fast your legs are moving. When cycling, it’s your pedal revolutions per minute. In running, it’s how many times your feet hit the ground. Higher cadence = smoother efficiency.
Di2
This stands for Digital Integrated Intelligence. Fancy name for electronic gear shifting. Instead of using cables, Di2 uses buttons and wires (or wireless tech) to shift your gears. It’s super smooth, fast, and reliable.
Disc Brakes / Rim Brakes
Two types of braking systems on bikes. Disc brakes stop better, especially in the rain. Rim brakes are lighter and simpler. Both work. It’s mostly personal preference.
Disc Wheel
A solid, spokeless rear wheel used for maximum aerodynamics in time trials and triathlons. They’re fast, they look cool, and they sound like a spaceship.
DNF / DNS
DNF = Did Not Finish
DNS = Did Not Start
Both happen. No shame. Every race is a learning experience.
Drafting
Riding behind someone to reduce wind resistance. It’s allowed in some triathlons (like short-course elite races), but banned in most age-group races. In swimming, it’s totally legal and a smart strategy.
Duathlon
Run, bike, run. Great for winter races or if swimming isn’t your thing.
Fly Mount / Fly Dismount
Getting on your bike while it’s already moving or jumping off just before the dismount line. It looks cool when done right. But practice. A lot.
Full Ironman / 70.3
An Ironman is a 3.8k swim, 180k bike, and 42.2k run (yes, a full marathon).
A 70.3 (aka half Ironman) is exactly half those distances. Still brutal. Still awesome.
Groupset
All the mechanical parts on your bike that make it go and stop, gears, brakes, shifters, etc. Shimano, SRAM, and Campagnolo are the big brands.
Indoor Trainer / Turbo Trainer
A setup that lets you ride your bike indoors. Great for winter. Brutal for boredom. Pair it with Zwift or ROUVY to stay sane.
Intervals
Training where you alternate between hard efforts and recovery. Like 3 minutes fast, 2 minutes easy. Great for building speed and endurance.
Kona
The holy grail. Kona, Hawaii is where the Ironman World Championship is held. Hot. Windy. Brutal. Legendary.
(More to come for the next post.)
Final Thought
You don’t need to memorize all this to race but knowing the lingo helps you feel like you belong. Because you do.
And if you ever forget what a brick session is or whether you’re tapering or just lazy, just come back to this list. We’ve got your back.