What Should You Wear Under A Tri Suit?


If you’re new to triathlons, you may be wondering exactly what kind of clothing you need. Choosing the wrong gear can cause you to be uncomfortable during your race, which isn’t great when it comes to, you know, racing.

Most triathletes understand the best piece of kit is a tri suit. It’s versatile, comfortable, dries quickly, and works well in all three events of a tri.

But what should you wear under a tri suit? How many layers are too many layers? Will it slow you down if you wear too much?

Thankfully, this is quite a simple question to answer. To understand the reasons behind it, you should know the basics of tri suits.

Here’s all the information you need to know about your tri suit and what you should wear underneath it.

Tri Suit Basics

The triathlon suit is designed to get wet and it will get wet even when worn under a wetsuit. The tri suits are thin with a streamlined fit, so that they can be worn on their own or under a wetsuit.

Both the men’s and women’s tri suits are supportive and form-fitting, which reduces drag and won’t weigh you down. When you’re fitting a tri suit, you’ll want it to be snug but you’ll find that it will stretch with your body without restricting your range of motion.

Tri suits are made from moisture-wicking material, which dries quickly after the swim. You’ll find that the tri suit won’t cling and restrict your range of motion as you head out on the bike ride.

For comfort and support while cycling, tri suits feature a built-in chamois in the shorts. But unlike traditional cycling shorts, the tri suits chamois is thinner to allow the athlete to run comfortably.

Before your first triathlon, you’ll want to complete a few rides in your tri suit to get accustomed to the feel of the padding. The chamois is thinner to allow you to run without it irritating or chafing your skin.

The moisture-wicking properties of the material of the tri suit will help to keep you cool and dry on the run portion. Tri suits have flat seams and this helps to reduce skin irritation or chafing when you’re running.

Make sure that you’ve had some practice in your tri suit before race day, so that you know it’s comfortable and won’t interfere with your race. The mantra to remember for all triathlon race days is “nothing new on race day.”

Two Types of Tri Suits

When it comes to getting a tri suit, you’ll find that there are a variety of brands to choose from. But tri suits come in either one-piece or two pieces. The tri suit you get will come down to what you feel most comfortable wearing.

A One-Piece Tri Suit

The one-piece suit is often the more favored suit by triathletes, as it does have a more streamlined fit. You’ll find that a one-piece tri suit won’t move around and you won’t have to worry about the top half of the suit riding up.

This helps with aerodynamics and it has fewer seams, which greatly reduces skin irritation and chafing.

It has one zipper that opens the front of the suit and with pockets in the back, where you can store gels or energy bars.

The only downside to a one-piece suit is that a bathroom break won’t be a quick stop.

A Two-Piece Tri Suit

The two-piece tri suit consists of a top that has a zipper in the front and form-fitting shorts. While this is less aerodynamic than the one-piece suit, it does provide you with more flexibility in terms of fit.

Depending on your body shape, you may find that you wear a different size top to the bottoms. This will let you find a fit that will be comfortable for your body type or if you’re a taller person.

You may find that you’re cooler in a two-piece suit, as the midriff is open, which allows for more air circulation. If you do need to make a quick stop at the bathroom, it’s easier to remove the bottom on a two-piece suit.

The other benefit of a two-piece suit is that you’re able to wear each piece of the suit separately when training. You’re also able to mix and match between the top and the bottom of the tri suit. This can come in handy if you’re entering the triathlon with a team and want to wear matching colors.

If you do decide to go with a two-piece tri suit, then make sure to go with a tank top rather than a crop top. This will provide a bit more sun protection as you go through the different legs.

Both the one-piece and two-piece tri suits come either with sleeves or without sleeves. You may find that you want a sleeveless tri suit if you prefer having unrestricted arm movement or if you’ll be attending a triathlon in a warmer climate.

What to Wear Under a Tri Suit

While it may feel strange at first, you don’t need to wear anything under a tri suit. It’s advisable not to wear underwear on race day under your tri suit.

Underwear can take a long time to dry when it’s wet. This can lead to chafing and saddle sores if you do have wet underwear on under your tri suit.

Women will find that there are some tri suits with built-in sport bras that do provide adequate support. However, for women who are larger than a C cup size, it would be best to wear a supportive sports bra under the tri suit for maximum support and comfort.

Do I Wear a Tri Suit for the Whole Race, Even the Swim?

Yes, you’ll wear the tri suit for the entire race. Your tri suit is designed to be worn through each leg of the triathlon, including the swim.

This will help you speed up your transition times and it’s also important to note that there’s no separate changing area at a triathlon. Triathlon rules stipulate that any nudity or indecent exposure during a transition can lead to instant disqualification.

You’re also not allowed to cycle or run topless, as this will lead to instant disqualification (for both men and women).

The tri suit gets you race-ready right from the start.

Do I Wear It Under My Wetsuit?

Both the one-piece and two-piece tri suits can be worn under your wetsuit. They’re made from thin, form-fitting material that won’t bunch up or ride up under a wetsuit.

They also aren’t thick enough to be uncomfortable or make putting the wetsuit on or taking it off difficult.

How Do I Get Changed?

Some of the big events, such as Ironman, will have gender-specific changing tents, where athletes can change for each leg.

But with the shorter triathlons, there isn’t a separate changing area, which makes wearing a tri suit vital on race day.

Photo of author


Ben is an avid road and trail runner, and has completed multiple marathons and ultras. A former running store owner, he now shares his knowledge and experience writing these articles.