The Rio 70.3 Bike Course: Tunnels, U-Turns, and Elevation Gain Nobody Can Agree On

The Course in Brief

90.1 km over multiple laps, entirely on roads closed to traffic. You start from Copacabana along Avenida Atlântica, head toward downtown through Botafogo, Flamengo and Santos Dumont airport, then enter the Marcello Alencar tunnel to the turnaround at Rodoviária Novo Rio, at km 15. From there you head back and repeat. It's a city bike course: wide avenues, tunnels, tight turnarounds.

Elevation Gain: The Race's Most Uncertain Number

Let's be honest here: the sources diverge wildly. Figures range from roughly 380 m up to a claimed 2,630 m, with intermediate estimates around 1,150 m. The official course page, for its part, describes it as flat. With a spread that wide, we're not publishing a number.

What to do, concretely:

• Download the official GPS file when available and load it onto your bike computer.
• Calibrate your expectations on a course recon, not on numbers you read online.
• Plan by power, not average speed: that way, uncertainty about the profile stops being a pacing problem.

What the sources all agree on not mentioning: long climbs. This is a technical course, not a climber's course.

The Critical Points to Memorize

The km 45 turn. This is where lap 1 splits from lap 2 and the bike finish. The turns are marked, but after two hours in the aero position your focus fades. Memorize the spot on the map and, if you can, go see it in person in the days before, even by car or on foot.

The tunnels. Entrances and exits mean abrupt light changes between darkness and full sun. If you're not used to it, the first pass will catch you off guard. Train your eyes: ride through the tunnels on recon if possible, and in the race lift your gaze slightly a few seconds before each entrance.

The turnarounds. Rodoviária Novo Rio at km 15 is a tight U-turn, and it's not the only one. Brake, turn, accelerate: it's a skill that costs watts if you do it badly. Train it. A loop with repeated U-turns, once a week in the final weeks, is worth more than one extra long ride.

The pavement. Mixed: smooth avenues and rougher stretches near the tunnels. Nothing dramatic, but keep a firm grip through the surface changes.

The Wind

Moderate onshore wind off the Atlantic, significant on the exposed stretches of Avenida Atlântica. There's only one rule: pace by power, not speed. If you chase km/h into a headwind, you burn your run. You'll hold the aero position for a long time: if you can't stay on your extensions for 2.5 hours, work on it now.

The Cut-Offs

The local rules set the bike cut-off at 5 hours from the swim start, including the swim leg and T1, with an intermediate checkpoint at km 66.7. The total time limit is 8h30. If you're a borderline finisher, do the math beforehand: write down your minimum split times and carry them with you on race day. A 45-minute swim plus a slow T1 leaves you about 4 hours net for 90 km: doable, but not with a badly handled flat.

What to Do This Week

1. Add a workout with U-turns and accelerations. 2. Check you can hold 60-90 continuous minutes in the aero position. 3. Set your power plan on a conservative target, to be confirmed when the official GPS file is released. 4. Practice flat repair with the gear you'll carry on race day: with cut-offs like these, lost minutes count double.