Free calculator

Drafting Calculator

The rider at the front pays full freight. Tucked in behind, the same speed can cost half the watts. Build your paceline and see what the pack is worth — speed at your power, watts per position, and group power.

Your effort

Power (watts) Rider weight (kg) Bike weight (kg)

Aerodynamics & tires

CdA (m²) 0.42 m²

Typical: ~0.42 upright on the hoods, ~0.30 in the drops, ~0.23 on a triathlon bike.

Tires

Crr

The line

Riders 6

Your position shared

Rotating pulls (everyone takes a turn at the front)

Companion weight (kg) Same as me

Route & conditions

Grade (%) 0.0%

Head wind (kph) Distance (km) Temperature (°C) Elevation (m)

Solo vs the line

Solo

33.3 kph

1 h 12 min over 40.0 km

In the line

39.8 kph19.3% faster

1 h 00 min over 40.0 km

The line at 39.8 kph

Group power (avg)

250 W

Power spread

82%

406W front

254W 2

225W 3

211W 4

204W 5

200W 6

With rotation everyone averages 250 W, but each pull starts at the front — expect surges near 406 W on the turn.

Where your watts go

Gravity 0 W 0%

Aerodynamic drag 205 W 82%

Rolling resistance 45 W 18%

Drafting shrinks the aero bar only — gravity and rolling resistance can't be sheltered. That's why drafting is worth far less on steep climbs.

More free tools

Single-setup speed & power calculator Plan a route with paceline drafting Compare two bike setups side by side

Train with structure

Turn your watts into a periodized plan built around your schedule.

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Frequently asked questions

How much power does drafting actually save?

Wind-tunnel and field studies put the second wheel at roughly 40% less aerodynamic drag than riding solo, with shelter converging around 55–60% deeper in a long line. Since aero drag is 70–90% of the resistance on flat roads, that translates to holding the same speed with 25–50% less power — or a much higher speed at the same power. On steep climbs the saving shrinks toward zero, because gravity, not air, is what you're fighting.

What does "rotating pulls" change?

Without rotation you stay in one slot and enjoy that slot's shelter all ride. With rotation everyone takes a turn at the front, so the sustainable effort is the average over all positions — a fair but harder deal than sitting in. The trade is speed: a working line goes much faster than a half-frozen one where everyone is hiding.

Does a bigger group keep helping?

Diminishingly. Going from 1 to 2 riders is the biggest jump there is; by 5–6 riders in a single file, adding another name to the line barely changes the shelter. A wide peloton shelters better than a narrow line, but this model assumes a single-file pace line — the conservative case.

Is drafting safe, and is it allowed?

Practice close riding at low speed before relying on it at 45 kph — keep your wheel a half-wheel back and off to one side, never directly behind the front wheel, and signal everything. In racing, drafting rules differ: it's standard in road and track racing, restricted in age-group triathlon (draft-illegal) and some gravel and time-trial events.