70.3 Bike Gear: TT Time Trial Bike vs. Road Bike – Which One Should You Choose?

Introduction

The 90 km bike leg of a 70.3 is the segment where age-group athletes can most easily gain time through equipment upgrades. However, TT (time trial) bikes and road bikes each have their pros and cons, and a hasty upgrade could actually set your performance back. This article systematically compares the two.

Core Differences Between TT Bikes and Road Bikes

Who Should Ride a TT Bike

• Already has 5,000 km+ of road bike foundation
• 90 km bike target is sub-2:45
• Race course is flat or gently rolling
• Has time and venue to adapt to the TT position

Who Should Ride a Road Bike + Clip-on Aerobar

• First or second 70.3
• Also frequently rides group rides outside of 70.3
• Course has significant climbing (e.g., Kenting’s rolling terrain)
• Limited budget: upgrading helmet and wheels offers better value

Upgrade Priority Order

1. Bike fitting (most important)
2. Aero helmet (saves 5–10W)
3. Aerobar / TT extension
4. Deep-section wheels (saves 8–15W)
5. Aero skinsuit
6. TT bike (consider last)

Kenting Course Terrain Considerations

• Mid-section has rolling hills with 200–300m of cumulative climbing
• Crosswind sections after the turnaround
• The road bike’s handling and descending advantages are significant on this course
• If choosing a TT bike, lower-profile wheels (40–60mm) are recommended to handle crosswinds

Practical Advice

• Regardless of which bike, get a full bike fitting first
• A TT bike requires at least 800km of adaptation accumulated over 8–12 weeks before race day
• Don’t switch to a new bike at the last minute for a 70.3; allow at least 4 weeks of break-in
• Train primarily in the aerobar position, with accompanying neck and shoulder stretching

Conclusion

Choosing between a TT bike and a road bike isn’t about “which is faster,” but “which one lets you hold your optimal position for the full 90 km.” First assess your training volume, course terrain, and race frequency, then decide how to allocate your budget. For most first- and second-time 70.3 athletes, a road bike with a good fit and lightweight aero upgrades is often the smartest choice.

Related Reading

• Triathlon Bike vs Road Bike Purchase Decision: Which Should Be Your First
• Triathlon TT Bike vs Road Bike: Which Suits Your Race
• Triathlon-Specific Bike vs Road Bike: Geometry, Aerodynamics, and a Purchase Decision Tree
• TT Bike vs Road Bike Trade-offs: Geometry, Integration, and Real-World Gains Under UCI Rules