Learn the triathlon aero position: how low is sensible, how to build stability and what the rules allow. With a progression and safety check.
Is the aero position worth it, or does it just hurt your back? The honest answer: it is worth it as long as you can actually hold it. On the bike, air resistance slows you most, and a lower position on the aero bars cuts it noticeably. In a study with seven cyclists and triathletes, the aerodynamic frontal drag area fell by 8.5 % when the bars were just 5 cm lower, and that gain outweighed the extra metabolic cost [3].
But lower is not automatically faster. In 19 cyclists, power and breathing got worse with a flatter torso, so there is a trade-off between drag and body function [2]. In another study the best compromise was a very flat hip angle of 12° for shorter time trials. There riders lost 16 W at threshold but gained more from the wind [1]. For you as an age-group athlete this means: find the position where you breathe calmly, do not pinch your hips shut, and can still hold it after 40 kilometres.
The aero position is an intermediate skill because you give up easy access to steering and brakes. Learn it in steps, not on race morning.
Prerequisite: you can ride safely with one hand off the bars, brake and steer. If you still wobble on the normal handlebar, practise that first.
Sit on the trainer and rest your forearms on the pads. Elbows sit under your shoulders, hands grip the shifters. Your back stays long and your neck loose. Milestone: you hold it for 10 minutes without neck or shoulder pinching.
Increase in blocks of 5 minutes up to 20 minutes in the position. Compare how your heart rate reacts at the same power. If it is clearly higher in the aero position, you are too low [2]. Milestone: 20 minutes with even breathing.
Ride on a quiet, straight road. At first keep your hands close to the brakes so you can sit up quickly. Look far ahead, not at the front wheel. Milestone: 10 minutes straight and stable, with no wobbling handlebar.
Before corners, crests, descents and narrow spots, go back to the hoods or at least to the brakes. In crosswind you only stay in aero if you control the bike safely. With others you never ride close, because you brake later in this position. Milestone: you change from aero to braking position in 2 seconds.
Train the position in your race sessions, including brick sessions before a run. A study of 14 triathletes found: when the hand position extends the hip more, muscle work on the bike moves slightly closer to that of running [5]. That is a hint, not a promise of a fast run.
The bike course is not harmless: in a review of 135 deaths and cardiac arrests in US triathlon, 15 deaths were trauma-related and happened on the bike course [6]. A rule of thumb from practice adds to this: in the aero position you reach the brake levers less easily, so your braking distance gets longer.
Stay within the rules: in races where drafting is not allowed, you may use the extensions as long as they do not extend beyond the leading edge of the front wheel. In races where drafting is allowed, extensions are not allowed [4]. While riding you may only rest your forearms in non-drafting races, and your hands grip the extension [4].
This guide explains and motivates; it does not replace coaching or a bike fit. If you have back or neck pain: sit up and have the position adjusted.
Do the head test: have yourself filmed standing still and check whether your head sits between your shoulders like in a tunnel. Lifting your head slightly often gives you the same air volume without the neck pain, and it improves your view. That is a practical trick, not a measured number.
As low as you can breathe calmly and hold your power. Studies show a trade-off between drag and body function [2]. A very flat hip angle of 12° was the best compromise only in shorter time trials [1].
That depends on position and body. A 5 cm lower handlebar cut the drag area by 8.5 % in one study [3]. Those are lab values from only seven participants, not your race result.
Only where drafting is not allowed. In races where drafting is allowed, extensions are not permitted [4].
That is unclear. A study of 14 triathletes found that more hip extension brings muscle work on the bike slightly closer to running [5]. Whether you run faster was not measured there.
That is individual. Plan several weeks with regular sessions (experience, not a study value).
Flying Mount: Jumping on the Bike in the Triathlon Transition