Bike Fit Basics

• • The 109% inseam rule: measure inseam (barefoot, book-to-crotch); multiply by 0.883 for saddle height from bottom bracket to saddle top. Starting point only.
• • Heel-to-pedal test: heel on pedal at 6 o'clock, leg should be straight but not locked. When clipped in with ball of foot, knee bends 25–30°.
• • Hips rocking? Saddle too high. Knees sore on top? Too low.
• • Adjust in 5 mm increments; ride for a few days before re-adjusting.

• • KOPS (Knee Over Pedal Spindle): with crank at 3 o'clock, plumb line from kneecap should fall roughly over pedal axle. Classic starting point for road bikes.
• • Tri bikes sit further forward: effective seat angle 76–80° (vs. 72–74° for road). This opens your hip angle for aero position and preserves run legs.
• • If new to aero, slide saddle forward by ~1 cm and nose down very slightly.

Reach test: in the drops (road) or on the pads (tri), your arms and torso form roughly a 90° angle. Shoulders should feel open, not cramped or overstretched.

• • Ball of foot over pedal axle. Mark the 1st and 5th metatarsal heads; midpoint should align with pedal spindle.
• • Float: most riders want 4–6° of rotational freedom. Reduce only if diagnosed by a fitter.
• • Q-factor: wider stance for bigger riders; narrower for slim-hipped riders. Most stock bikes are fine — don't tinker without reason.

• • Elbow pad width ≈ shoulder width. Narrower is more aero but harder to ride far.
• • Pad stack & reach: back flat or slightly curved, not hunched into arms.
• • Extensions: angled slightly up (10–15°) unless you're very flexible.
• • Eyes forward. If you can't look 50 m down the road comfortably, position is too aggressive.

Never change aero position the week of a race. Ride any new fit for at least 3–4 weeks before racing.

• • Buying a new bike (especially a tri bike).
• • Pain that doesn't resolve with home adjustments.
• • Numbness, hot spots, saddle sores.
• • Power drop between aero and road position.
• • Before a goal 70.3 or Ironman.

Budget $150–300 for a basic fit, $300–500 for a tri-specific or motion-capture fit. Worth every cent — it can add watts, take away pain, and save you from buying a new saddle every three months.