AI quick summary
- A TT is sustained at 95-105% FTP for 10 to 40 miles; the engine is threshold, the ceiling is your CdA.
- Build threshold with long sweet-spot and over-under intervals; train your aero position weekly from week one.
- Aerodynamic drag is 70-80% of total resistance on the flat — position work is worth as much as power work.
- Pace with power: target FTP for short TTs, 92-95% for 40K; negative-split if you can.
/ 01
The demands of the time trial
A flat-to-rolling time trial is the most physiologically predictable event in cycling: a sustained effort at or just below FTP for the duration of the race. A 10-mile TT takes 20-25 minutes for most riders and is paced around 100-105% FTP; a 25-mile (40 km) TT takes 55-65 minutes and is paced at 92-96% FTP. There are no surges, no coasting, no hiding — you produce power every second.
Two things decide your result: the sustained power you can hold (your threshold engine), and the speed that power translates into (your aerodynamic drag area, or CdA). You train both, and you cannot skip either.
/ 02
Power and aero — the two levers
On the flat, 70-80% of your power goes into overcoming aerodynamic drag. Cutting CdA by 10% — through a better position, a skinsuit, deeper wheels, or a cleaner cable setup — is often worth more than raising FTP by 10%, and it is usually easier and cheaper to achieve.
For power, the threshold engine is the foundation. FTP is the single best predictor of TT performance, and a 4.0 W/kg rider will beat a 3.5 W/kg rider of similar aerodynamics on a flat TT almost every time. The plan below trains FTP first, then layers race-specific over-unders on top.
/ 03
The 8-week plan
Eight-week TT build — threshold volume first, then over-unders and aero-specific work.
| Week | Focus | Key session 1 | Key session 2 | Volume |
|---|---|---|---|---|
| 1 | Base / sweet spot | 4x10 min @ 90% (in TT bars) | 3x15 min @ 88% | 9-11 h |
| 2 | Sweet spot | 4x12 min @ 92% (in TT bars) | 3x20 min @ 85% | 9-11 h |
| 3 | Threshold | 3x15 min @ 95% | 4x8 min @ 100% | 10-12 h |
| 4 | Threshold | 3x20 min @ 95% | 4x10 min @ 100% | 10-12 h |
| 5 | Over-unders | 4x12 min @ 95% with 30 s @ 110% every 3 min | 3x15 min @ 100% | 10-11 h |
| 6 | Over-unders | 5x10 min @ 95% with 30 s @ 115% every 2 min | 2x20 min @ 95% | 10-11 h |
| 7 | Specific TT | 2x20 min @ 95-100% (full TT setup) | 4x5 min @ 105% | 9-10 h |
| 8 | Taper / event | 3x5 min @ 100% (Tue) | 2x10 min @ 95% (Thu) | 7-8 h |
/ 04
Threshold and over-under work
Long threshold intervals (2-4 sets of 15-20 min at 92-96% FTP) are the heart of TT training. They raise your sustainable power and train the psychological discipline of holding a steady, painful pace — which is most of what a TT actually is.
Over-unders build the lactate tolerance you need for headwind sections, small rollers, and turnarounds. Ride 3-5 min at 92% FTP with 20-30 second surges to 110-115% embedded. The surges mimic the micro-variations of a real TT course, where you momentarily produce more power and then have to clear the lactate without dropping your average.
/ 05
Aero position practice
Ride your TT bike or TT bars at least once a week, every week, from week one. The position is uncomfortable at first — neck, shoulders, and hip flexors all need to adapt — and you cannot show up on race day having only ridden it five times. Start with 20-minute blocks at sweet spot and build to holding the bars for an hour or more by week 6.
If you can, get aero tested. A field test with a power meter on a calm day (virtual elevation via the Chung method) or a wind-tunnel session with a fitter will typically lower your CdA by 10-20% — often worth 1-3 minutes over 40 km. Helmets, skinsuits, and shoe covers are the cheapest gains; a front wheel and base bar are the next steps.
/ 06
Pacing and race-day execution
Pace to power. For a 10-mile TT, target 100-102% FTP; for a 25-mile, 92-95%; for a 12-hour, 75-80%. The first 5 minutes should feel controlled; the middle is steady work; the last 5 minutes you will be at the limit. Use the first kilometre to settle into rhythm, not to set a fast split.
Negative-split if you can — start 3-5% under target, build to target by halfway, finish over. Most blow-ups come from a 110% FTP opening kilometre that feels fine for 60 seconds and then collects interest for the next 20 minutes. Take the turnarounds conservatively; 5 seconds lost in a cautious U-turn is better than 30 seconds lost in the 5 minutes after an over-cooked one.
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