# Triathlon T1/T2 Transition + Bike CdA/Yaw + Off-the-Bike Pacing Planner

Plan long-course triathlon execution: T1/T2 transition checklists and time budgets, segment-by-segment bike pacing from the road-load power model with CdA 0.18–0.30 and yaw-dependent aero, run-off-the-bike pace targets with running-economy decay, and race-day carb/fluid totals.

> Canonical page: https://elysiatools.com/en/tools/triathlon-t1-t2-transition-bike-cda-aero-yaw-wind-deficit-pacing-planner

- **Category:** Sports

- **Keywords:** triathlon, ironman, transition, t1, t2, cda, yaw, crosswind, power pacing, off the bike, running economy, fueling, brick

## Overview

The bike leg is solved segment by segment from the road-load power equation (aero drag + rolling + gradient) with head/cross wind decomposition, yaw-attenuated CdA and altitude/temperature-corrected air density; the run applies off-the-bike economy decay, transitions get itemized second-by-second checklists, and fueling totals carbs and fluid at your hourly rates.

## Inputs

- **Race format** (select)
- **Planned swim time (minutes)** (number)
- **T1 time budget (minutes)** (number)
- **T2 time budget (minutes)** (number)
- **Rider mass (kg)** (number)
- **Bike + kit mass (kg)** (number)
- **Riding position** (select)
- **Field-test CdA override (0 = use position default)** (number)
- **Aero equipment depth** (select)
- **Rolling resistance Crr** (number)
- **Course altitude (m)** (number)
- **Air temperature (°C)** (number)
- **Target bike power (watts)** (number)
- **Course segments** (textarea): One per line: name, distance_km, elevation_gain_m, wind_kph, wind_dir_deg (0°=headwind, 90°=right cross, 180°=tailwind) e.g. Lakeside out, 30, 80, 14, 0 Crosswind stretch, 25, 40, 18, 95 Tailwind home, 35.1, 60, 12, 175
- **Fresh run pace (sec per km)** (number)
- **Off-the-bike economy decay (%)** (number)
- **Run distance (km)** (number)
- **Carbohydrate rate (g per hour)** (number)
- **Fluid rate (ml per hour)** (number)

## When to use

- Formulating target wattages, splits, and nutrition intake for an Ironman 70.3, Ironman 140.6, or custom triathlon.
- Evaluating the time impact of equipment choices, aerodynamic riding positions, and course wind conditions.
- Setting realistic marathon or half-marathon pacing targets adjusted for off-the-bike running economy degradation.

## How it works

- Enter race distance parameters, target bike power, rider and bike mass, position CdA, rolling resistance, and environmental variables like altitude and temperature.
- Define course segments with specific elevation changes, wind speeds, and wind directions to calculate effective yaw and aerodynamic resistance.
- Specify fresh run pace and expected economy decay alongside planned transition budgets and hourly nutrition intake.
- Generate comprehensive outputs including segment bike velocities, projected run splits, transition checklists, and overall race-day carb and fluid requirements.

## Use cases

- Optimizing power distribution across multi-segment bike courses with varying wind exposures.
- Determining realistic run paces off the bike to avoid early pacing blowouts on race day.
- Structuring transition execution time budgets and calculating total required race nutrition supplies.

## Frequently asked questions

### How does wind direction affect the bike speed calculation?

Wind speed and angle are decomposed into headwind/tailwind and crosswind components to compute apparent wind velocity, yaw angle, and yaw-adjusted CdA.

### Can I use an exact CdA from a velodrome or wind tunnel test?

Yes, enter your measured value in the CdA override field to bypass standard position presets.

### What does the running economy decay percentage represent?

It accounts for physiological fatigue and muscle damage accumulated during the bike leg, slowing your fresh standalone running pace.

### How are nutrition totals calculated?

Hourly carbohydrate and fluid targets are multiplied across total projected race time, covering swim, transitions, bike, and run legs.

### How does elevation gain impact segment pacing?

Elevation gain is converted to an average road gradient, which the physics engine uses to calculate gravity resistance alongside aero drag and rolling resistance.

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