AI 速览
- Fit is everything on a TT bike — a 1cm saddle shift changes both power and drag
- Extension shape and pad width should match your shoulder anatomy, not your favorite pro's setup
- Hydration between the arms is faster than behind the saddle and easier to drink from
- Gearing for TTs is about holding power in aero, not maximizing top-end gear
/ 01
Fit Is Everything
On a road bike, position is important. On a TT bike, position is the entire point. A 1cm shift in saddle fore/aft changes both power output and aerodynamic drag — the relationship is non-linear and a bad fit costs you minutes, not seconds.
Get a proper TT fit. The saddle is further forward (5cm behind the BB for UCI, less for triathlon), the front end is lower, and the hip angle at the top of the stroke is closed compared to road. Closing the hip angle too far drops power; opening it too far adds drag. The fit finds the line.
/ 02
Extensions Match Your Shoulders
Extension shape — straight, S-bend, or ski-bend — should follow your shoulder anatomy. Narrow shoulders with a wide S-bend creates wrist discomfort; wide shoulders on a straight bar forces elbows out. The pads sit directly under the point of your shoulder, not under the elbow.
Pad width is the most overlooked TT fit dimension. A pad-to-pad distance 1-2cm narrower than your shoulder width is the modern aero standard — but only if you can hold the position. Going too narrow causes tension and reduces sustainable power.
Extension types and rider fit
| Extension type | Wrist angle | Best for |
|---|---|---|
| Straight | Neutral | Open shoulder anatomy |
| S-bend | Dropped wrist | Narrow shoulders |
| Ski-bend | Slight upward | All-round, most popular |
| Superman | Extended forward | UCI banned, tri only |
/ 03
Hydration Between the Arms
A bottle between the arms (BTA) is both the fastest hydration position aerodynamically and the easiest to drink from in aero. Behind-the-saddle bottles are second-best; frame bottles behind the stem are third. The aim is to drink without breaking aero shape.
Long-course events need storage: spare tub, CO2, multi-tool, nutrition. A behind-saddle mount for the tub and a top-tube bento box for nutrition keeps weight centralized and aero-neutral. Avoid seat-post-mounted bags — they disrupt airflow over the whole rear of the rider.
/ 04
Gearing for Holding Power
TT gearing is about holding power in aero, not maximizing top-end. A 54/42 chainset with an 11-28 cassette gives the right ratios for flat 40km efforts; for rolling courses, a 53/39 standard with the same cassette handles the punchy climbs without losing the top end.
Pushing bigger gears at lower cadence (75-85 rpm) is more aero-efficient than spinning 100+ rpm in smaller gears, because high cadence introduces upper-body movement. Most TT specialists ride 80-90 rpm, not the 95-105 rpm that road racing rewards.
/ 05
Fast Means Visible
On a TT bike you're low and forward, hard to see from a following car, and often riding unfamiliar courses in early morning or evening light. A solid flashing rear light on the seat post is non-negotiable for training. For racing, check the rules — many TTs now require them.
Brake setup matters more than people admit. You're in extensions, the brakes are on the base bar, and grabbing them in a hurry is a two-stage motion (sit up, reach for the lever). Practice panic stops in a parking lot until the muscle memory is automatic. Crashing from a TT bike is uglier than from a road bike because the geometry is less forgiving.
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