The power output you can sustain on the road bike vs the time trial bike can differ. That balance of getting the position right so the athlete is able to ride at a solid power output while being as aero as possible can be a tricky one to get right.

But what is a good and bad power difference between a road bike and a time trial bike.

Power loss on a TT bike

• 0-3% – Excellent – Very well adapted to the TT position. Likely optimized bike fit and positional strength.
• 4-7% – Good/OK – Some loss of efficiency but within normal range. May improve with more TT training
• 8-12% – Poor – Indicates significant adaptation issues, positioning problems or strength imbalances.
• >12% – Major Concern – Likely a combination of positional limitation, poor muscle engagement or aerodynamic inefficiencies

If the drop off is greater than 8%, a suggestions could be

1. Insufficient TT position adaptation – Need more time training in the aero position.
2. Bike fit inefficiencies – Poor hip angle, too aggressive reach or restricted breathing.
3. Muscular imbalances – Weak glutes, hip flexors or core limiting power generation.