Bicycle Aerodynamics

summary:

Overview & Method

Torsten Frank ran extensive real-world tests across summer–autumn, logging many comparison rides with careful protocols.
He measured aerodynamic performance (CdA and watts) for eight different bikepacking setups.

Handlebar roll: Bad aerodynamics – about +2.1 aeroPOINTs slower than no bag.
Aerobar bag: Surprisingly good – –1 aeroPOINT faster than no bag at all.

Tailfin AeroPack (trunkbag): Makes you 0.5 aeroPOINTs faster than no bag – aerodynamically beneficial.
Apidura Expedition Saddle Pack (14 L): Neutral – no faster, no slower than no bag.
Panniers:
- 2 × 5 L Mini-Panniers (Tailfin): About 0.5 aeroPOINTs slower.
- 2 × SL22 Panniers (~20 L each): About 0.9 aeroPOINTs slower.
- One SL22 pannier instead of two Minis: also 0.5 aeroPOINTs slower, but with much higher volume (22 L vs 10 L).

Tailfin AeroPack + Mini Panniers (2 × 5 L) or Tailfin AeroPack + one SL22 pannier perform about the same as no bags or the Apidura Saddle Pack – but give you far more volume.
In practice, you can carry up to ~36 L of gear (AeroPack + SL22 pannier) with no aero penalty compared to a minimally loaded bike.

Shape & placement matter:
- Across-the-wind bags like handlebar rolls disrupt airflow → big drag penalty.
- Streamlined bags behind the rider (AeroPack, aerobar bag) smooth airflow → sometimes reduce drag.
Aerobar bag acts like an aero fairing – it channels the wind like on a TT bike.
Side panniers sit in the wake of the rider → cause turbulence, but less severe than expected.

Avoid handlebar rolls if you care about aerodynamics.
Aerobar bags are a surprising aero win.
Best rear options:
- Tailfin AeroPack → actually makes you faster.
- Apidura 14 L Saddle Pack → aero-neutral, simple solution.
- For bigger loads: Tailfin + Mini or SL22 panniers → up to 36 L with no aero loss.

👉 So the choice isn’t about drag anymore – it’s about comfort, handling, and volume needs.