We’ve all see that guy starting the run leg of his first triathlon. As he exits transition, he strides purposely forward, wearing both his game face and his bike helmet.

Stupid mistakes happen. Particularly in a sport with three different disciplines (four if you count transitions; five if you count the pre-race vacuum-packing of flesh into wetsuit) and lots of rules. But many errors are avoidable, especially with a little pre-planning. We asked three coaches what "oopsie" moments they see most often, even among experienced athletes. From mistakes made in training and race planning, to errors after the finish line, here’s what they see triathletes doing over and over again.

Signing Up for the Same Race as Your Friends

 

Triathlon is a social sport, but you really should choose your races based on your own needs, says Jen Rulon, a triathlon coach. “If you’re scared of an ocean swim, but all your friends are doing a race in the ocean, that’s not going to be your best choice.” Same with picking a mountainous course, or one known for hellish temps. Set yourself up for success with a race that plays to your strengths. Then, if you crave social interaction, ask a friend to tag along as your "race Sherpa” for the weekend.

 

Buying Every Gadget on the Market

 

"I tell people not to spend a lot before their first race. You need to see if you like the sport first," says Amy Simonetta, a Florida-based triathlon coach and physical therapist. If you like the sport, then you can start exploring how you'd like to dispose of all of your disposable income. But to begin with, keep it simple. “Borrow a bike, or ride the bike you have,” she says. If you decide never to race again, you won’t be out a dollar.

Some gadgetry can be confusing too. Heart rate and power meters only work if you know how to plan your training to maximise results. If all you’re seeing is numbers, you may assume pushing for higher numbers is always better. That’s a one-way ticket to Burnout City. And just because it exists doesn’t mean it’s the right choice for you. Those wheels with deep, aerodynamic rims may look cool, but they’re a nightmare in windy conditions. If you're a beginner, you'll regret the purchase.