Swim Drafting: Legal Free Speed
Unlike drafting in cycling road races, which is illegal, drafting in the triathlon swim leg is completely legal and encouraged. Research shows that drafting correctly can save 8%–18% of oxygen cost, equivalent to a heart rate 6–10 beats lower at the same speed.
Three Drafting Positions
| Position | Energy Saved | Risk | Best For |
|---|---|---|---|
| Directly behind, in the feet’s bubble wake | Highest, ~15% | Prone to swallowing spray, getting kicked | Swimmers of similar pace |
| Behind and to the side of the hip | ~10% | More comfortable, easier to sight | Recommended for most |
| Swimming side-by-side at the shoulder | ~5% | Allows overtaking and sighting | When preparing to pass |
How to Find Your “Locomotive”
In the first 200m after the start, observe your surroundings: find someone pacing 2–3 seconds/100m faster than you with a steady kick, and slot in behind and to the side of their hip. The ideal leader is “just a bit stronger than you”—too strong and you’ll get dropped; too weak and there’s no benefit.
Rotation and Etiquette
On long-distance races (70.3/IM swim legs), you can take turns leading with a companion, swapping every 300–400m so both save energy. The unwritten rule in the triathlon community is that the leader doesn’t deliberately try to shake off the drafter.
Risk Management
Drafting too close means constantly swallowing the leader’s spray and getting your goggles hit; keep half a body length back, lock your sight on the leader’s hips rather than their feet, and sight every 6–8 strokes to confirm you haven’t drifted off course.
Converting the 8% into Finish Time
For an age-group athlete swimming 1500m in 25 minutes, saving 8%–12% of oxygen cost means a heart rate 6–10 beats lower at the same speed, which equates to preserving about 5%–8% more whole-body energy when you exit the water. In an Ironman, this “savings” carries over to the final marathon, and in practice can translate to not slowing down in the last 10km and finishing 6–12 minutes faster overall. The swim itself only saves 1–2 minutes; the real payoff is the energy conserved on the bike and the run.
Common Drafting Mistakes and Fixes
| Mistake | Consequence | Fix |
|---|---|---|
| Drafting too close and constantly kicking feet | Both swimmers slow down, conflict arises | Drop back to half a body length, lock on hips not feet |
| Leader’s pace fluctuating | Repeated surges burn more energy | Switch to a leader with a steadier kick |
| Drafting without sighting | The whole group drifts, swimming 100m+ extra | Sight landmarks yourself every 6–8 strokes |
| Drafting someone slower than you | Dragged down while thinking you’re saving energy | The leader must be 2–3"/100 faster than you |
The most underestimated mistake is the fourth one: many people slot in and feel “easy,” but they’re actually being slowed down—what they’re saving isn’t energy, it’s their placing.
I’m often amazed at how many people spend a fortune on a wetsuit but won’t spend ten minutes learning to draft. The 8% saved in the swim will pay you back double in the final 10km of the marathon. Drafting isn’t cheating; it’s smart.
Related Reading
- Open-Water Drafting Benefits and Techniques: Swim Smart and Save 30% Energy
- The Complete Open-Water Drafting Guide: The Energy-Saving Map of 18% Behind the Feet, 12% at the Hip
- Olympic-Distance Swim Drafting Techniques: The Invisible Weapon for Saving Energy
- Open-Water Drafting Technique: Energy-Saving Differences Between the Feet and Hip Positions
CT 喇低賽) 武嶺牽車 才是王道 西進牽車四小時內秘訣 攝手位置 如何判斷 防抽筋小秘訣
7 年前
自助洗車場 洗單車 50元有找 清鍊條大法 居然還有小小兵
7 年前
洗單車神器 吹水機! 實際洗車用用看 暴力洗鍊條大法 | 公路車 | CT Yeh
4 年前
#東進武嶺 全程實況錄影 5小時半 #夏季KOM #太魯閣 Taiwan KOM Challenge Reality Video Taroko scenery
7 年前
如何 搶 #中央山脈 報名 #公路車 #報名 #搶票
7 年前
戰略) Zwift Race 如何咬在第一集團 如何評估自己要開多少推力 (請開1.5倍速看)
7 年前
2019 夏季KOM 5小 完賽心得 準備攻略 東進武嶺 夏季登山王之路 Taiwan KOM Challenge
7 年前
福隆鐵人團練隨拍
8 年前