Electric Scooter Gradeability: 20% Grade Is Not 20 Degrees

A 20% grade is approximately 11.3°, while a 20° incline is approximately 36.4% grade. Confusing the two can substantially change the route requirement in an electric scooter quotation. Neither figure, on its own, establishes the speed, load or duration a vehicle can sustain on that slope.

For importers selecting seated electric scooters or electric motorcycles, read the slope unit first, then compare what the supplied result actually demonstrates. A brief ramp ascent, a restart on a slope and a sustained climb answer different purchasing questions.

What does percent grade measure?

Percent grade is vertical rise divided by horizontal distance, multiplied by 100. The US Geological Survey’s slope explanation uses this rise-over-run definition. Horizontal distance is the level projection, rather than the distance travelled along the inclined surface.

A rise of 2 metres over 10 horizontal metres gives 2 ÷ 10 × 100 = 20%. For a straight slope, the equivalent angle is arctan(0.20), approximately 11.3°. Conversely, a 20° angle gives 100 × tan(20°) ≈ 36.4%.

20% grade ≈ 11.3°

Over 10 horizontal metres: 2 metres rise.

20° incline ≈ 36.4% grade

Over 10 horizontal metres: approximately 3.64 metres rise.

A comparison example: two quotes that both say “20”

The following offers are hypothetical teaching examples, not BG EBIKE specifications or test results.

The first conclusion is definite: the stated slopes differ. Offer B describes a steeper slope. The second conclusion is limited: the entries do not establish which complete vehicle performs better on the buyer’s route. Both still omit the conditions and outcome needed for that comparison.

Suppose the intended route contains a 15% climb. Geometrically, both stated maximum values exceed 15%. That does not establish that either vehicle can carry the intended load up the whole section at the required speed. Matching a route to a claimed maximum is only an initial screening step.

Starting on a slope is different from continuing up it

A vehicle entering a short ramp while already moving has not demonstrated a restart halfway up that ramp. Likewise, reaching the top at a very low speed does not establish that the vehicle meets a delivery schedule or a buyer’s minimum uphill speed requirement.

VIDA’s gradeability explanation distinguishes starting from rest, load, battery charge, surface conditions and incline length. Its discussion illustrates why the slope number needs context; its vehicle capabilities should not be transferred to another manufacturer.

For a route involving stop-start traffic, the useful evidence includes the specified starting condition. For a long climb, it includes the climb length and speed achieved over that section. Keep the requested operation within the manufacturer’s permitted use and evaluation procedure.

Turn a route requirement into a useful comparison

A more useful request than “Can it climb 20?” is: “Our route includes a 15% section over 200 metres along the road. Please identify the proposed battery and vehicle version and provide the available climbing information for our intended rider and cargo load, including uphill speed and whether a start from rest is covered.”

Here, 15% describes steepness and 200 metres describes the section length along the road. They are separate inputs. The supplier’s response may support the requirement, identify a different suitable build, or show that a sample evaluation is needed. It should not silently replace the requested load or route with an easier demonstration.

Do not convert motor watts into a universal climbing angle. A motor-power entry alone does not describe the complete vehicle’s available wheel force, traction or sustained operating limits. Our rated versus peak motor power guide explains why the power definition also matters when comparing offers.

Finally, an uphill capability claim is not a downhill braking assessment. Keep the route’s stopping and descent requirements in the complete vehicle evaluation; the seated-scooter brake layout guide addresses a separate part of that choice.