AI 速览
- Position is everything: aerodynamic drag accounts for 80%+ of resistance at TT speed. A good TT position (low, flat back, narrow elbows, aero helmet) saves 30–50 watts vs a road position — more than any equipment upgrade
- Pacing: even-split is fastest for most riders — hold the same power from start to finish. Negative-split (starting easier and finishing harder) is safer for first-timers who tend to go out too hard. Positive-split (fading) is always slower
- Equipment by ROI: TT bars + aero helmet (the position) > aero suit/skinsuit > deep-section front wheel > aero frame > disc rear wheel. Spend on position before spending on equipment
- If you have a power meter, TT pacing is simple: target 100–105% of FTP for a 20km TT, 95–100% for 40km. Hold it steady. The rider who fades loses the most time
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Position — the biggest free speed
At time-trial speed (40+ km/h), aerodynamic drag is 80%+ of the total resistance you overcome. Your body is 70–80% of that drag. So the single biggest speed improvement is reducing your body's frontal area — getting low, flat, and narrow.
TT bars (aero extensions) let you rest your forearms on pads and grip forward extensions, dropping your torso nearly horizontal. This position, combined with a TT helmet (teardrop shape that smooths airflow off your back), can save 30–50 watts compared to a road position on the hoods. That's 3–5 km/h of free speed — more than any wheel or frame upgrade.
The trade-off: a low TT position restricts breathing and power output (your diaphragm is compressed). The optimal position is the lowest you can sustain at full power for the duration of the TT. A professional bike fit (with aero testing) is worth more than any equipment purchase.
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Pacing strategy
The even-split is the gold standard. At constant power, you produce the fastest time because you never waste energy going harder than necessary (the cost of going harder increases nonlinearly with speed — air resistance is proportional to velocity cubed). The practical challenge: resisting the urge to go hard in the first 5 minutes when you feel fresh and the adrenaline is flowing.
If you don't have a power meter: pace by perceived effort and heart rate. Aim for an effort you can sustain — it should feel hard but controlled from the start. If your breathing is ragged in the first 5 minutes, you've gone too hard. Back off immediately; the TT is lost in the first 5 minutes by going too hard, not in the last 5 minutes by going too easy.
TT pacing strategies by rider type and experience.
| Strategy | How | Best for | Risk |
|---|---|---|---|
| Even-split | Same power start to finish | Experienced riders with power meter | Requires discipline to not overpace early |
| Negative-split | Start 5% easier, finish 5% harder | First-timers; hilly courses | Leaves time on the table if too conservative |
| Positive-split | Start hard, fade | Never optimal | Always slower — the fade costs more than the fast start gains |
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Equipment ROI ranking
Time-trial equipment ranked by speed-per-dollar. Position first, equipment second.
| Item | Watts saved (est.) | Cost | ROI |
|---|---|---|---|
| TT bars + position optimization | 30–50 W | $200–500 + fit | Highest |
| Aero helmet (teardrop) | 10–15 W | $200–400 | High |
| Aero suit / skinsuit | 10–20 W | $150–400 | High |
| Deep-section front wheel (60–80mm) | 5–10 W | $800–2,000 | Medium |
| Aero frame (TT-specific) | 5–15 W | $3,000–8,000 | Low |
| Disc rear wheel | 3–8 W | $1,000–2,000 | Low (only in calm conditions) |
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Cornering and hills
On a TT bike, cornering is compromised — the TT bars reduce steering leverage and the position lowers your center of gravity. Brake before corners (TT bikes have less braking power in the aero position), take a wide line, and accelerate smoothly out. Don't brake in the corner — the aero position makes bike handling sketchy under deceleration.
On hills: stand up and get into the hoods (if your TT bars allow) for steep sections. The aero position on the extensions is less efficient above ~8% gradient (where weight, not aerodynamics, is the limiting factor). For rolling terrain, stay in the aero position on the descents and flats; sit up on the climbs. The key: never coast. Even on a descent, keep pedaling — at TT speed, pedaling is always faster than coasting.
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