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Wind tunnel ranks 12 aero bikes, Factor and Cervélo top.

Source: cyclingnews.com

TL;DR

Cyclingnews wind tunnel tested 12 dedicated aero road bikes for 2025 models at Silverstone.
Factor Prototype topped bike-only tests at 61.51w drag; Cervélo S5 led with-rider at 273.12w, tie within error.
Aero designs save up to 27.57w over 2015 baseline, equal to 2 minutes faster in 40km time trial at 250w.

The story at a glance

Cyclingnews Labs put 12 all-out aero bikes through wind tunnel tests, including the Factor Prototype, Cervélo S5, and Colnago Y1Rs. They measured drag in three setups: bike only with stock wheels, with rider, and bike only with standardised Enve wheels. The tests come amid 2025's return of pure aero race bikes after years of aero all-rounders. Results show tight competition at the top, with big gains over older frames.[[1]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025/)

Key points

Testing protocol: CdA measured at 40km/h across seven yaw angles (-15° to 15°), weighted per Nathan Barry's method; rider tests at 90rpm cadence; error margins 0.33w bike-only, 1.73w with rider; all size 56cm frames.
Top performers: Factor Prototype won both bike-only categories (62.65w standardised wheels); Cervélo S5 and Factor tied with-rider top (273.12-273.17w); Colnago Y1Rs third overall (276.78w with rider).[[1]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025/)
Bottom of pack: Bianchi Oltre RC last with-rider (285.24w, pre-new UCI rules); Elves Falath EXP best value but slower bike-only (77.58w stock).
Wheel impact: Stock wheels mattered—Van Rysel 1.41w faster with own Swissside vs Enve; Argon 18 and Cube gained from Scope wheels.
Gains vs baseline: 2015 Trek Émonda ALR needed 300.70w with rider; leaders save 27w, hitting 38.84km/h at 250w vs baseline 37.61km/h.
Full bike list: Argon 18 Nitrogen Pro, Bianchi Oltre RC, Cervélo S5, Colnago Y1Rs, Cube Litening Aero C:68X, DARE Velocity Ace-AFO, Elves Falath EXP, Factor Prototype, Merida Reacto 9000, Ridley Noah Fast 3.0, Scott Foil RC, Van Rysel RCR-F.

Details and context

Tests highlight how new UCI rules allow deeper tubes and aggressive shapes, pushing aero further than 2024 all-rounders like Tarmac or Madone. Factor's prototype—wide fork, deep bayonet head tube—dominated bike frames alone but stayed close with rider, where position trumps frame. Cervélo S5 excelled rider-on despite SRAM 1x groupset and mid bike-only results; they note "bikes don't ride themselves."[[2]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025)

Mid-pack clustered within error margins (Colnago, DARE, Ridley, Van Rysel around 278-280w), showing aero parity except extremes. Bianchi lagged as older design; Elves impressed for price despite frame drag.

Savers translate to real speed: top bikes cut 2:01 off 40km TT vs baseline at 250w output.

Key quotes

"The fastest bike we've ever tested in our with-rider test." —on the Cervélo S5.[[1]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025/)
"Compares apples to pears." —Bianchi's Claudio Masnata on their pre-UCI update frame.[[1]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025/)

Why it matters

Pure aero bikes now clearly outpace all-rounders in drag tests, reshaping pro race and TT choices. Riders gain seconds per hour from frames alone, plus wheel tweaks, but rider fit remains key within 10-15w spreads. Watch Factor's production version and 2026 UCI tweaks for more frame extremes.[[1]](https://www.cyclingnews.com/features/wind-tunnel-tested-12-aero-bikes-2025/)