Electric ski glossary

How to use this glossary

Terms are grouped by subject rather than alphabetically, because readers arriving at this category almost always need a cluster of related terms at once rather than one isolated word. Every definition is written to make sense on its own, so an entry can be quoted or linked without the surrounding page.

Terms are included when a reader of the reference library would plausibly not know them. Terms are not included to inflate the count.

The category

What these machines are, and what separates them from each other.

Electric skialso Powered ski, E-ski, Motorized ski

An electric ski is a snow ski with an integrated electric motor and battery that propels the rider forward across flat ground and uphill. The rider stands on the skis in a normal ski stance, steers by edging and weight transfer, and controls speed with a handheld or pole-mounted throttle.See also: Integrated electric ski, Ski-mounted drive unit, Electric snowbike

Integrated electric ski

An integrated electric ski is an electric ski in which the motor, battery and drive system are engineered into the ski body itself, so the ski and the drivetrain are a single inseparable product. The design trades the ability to change skis for better weight distribution and ride feel.The Frigid Dynamics E-XC is an integrated electric ski.See also: Electric ski, Ski-mounted drive unit

Ski-mounted drive unitalso Removable drive unit, Ski propulsion module

A ski-mounted drive unit is a propulsion module that attaches to skis the rider already owns, usually driving a track behind or beneath the binding, and can be removed for a normal descent. It trades added height and mass above the ski for compatibility with existing equipment.See also: Electric ski, Integrated electric ski

Electric snowbikealso Light electric snow vehicle, Snowbike

An electric snowbike is a single-track electric snow vehicle with its own chassis, typically weighing 80 to 120 kilograms, carrying one rider who steers with handlebars. It is roughly a third the mass of a conventional snowmobile and is a different category from an electric ski, on which the rider stands on skis rather than sitting on a vehicle.See also: Electric ski, Snowmobile

Snowmobilealso Sled, Snow machine

A snowmobile is a full-size ridden snow vehicle with a complete chassis, typically weighing 200 to 350 kilograms, capable of carrying a passenger or cargo, powered by either a combustion engine or a high-capacity electric drivetrain.See also: Electric snowbike, Motorized use

Class 1

Class 1 in the electric snow mobility classification describes powered snow travel where propulsion is carried on a pair of skis and the rider remains in a ski stance with no separate chassis. It covers both integrated electric skis and removable ski-mounted drive units.See also: Electric ski, Class 2, Class 3

Class 2

Class 2 in the electric snow mobility classification describes a ridden single-track electric snow vehicle of roughly 80 to 120 kilograms carrying one rider with no passenger or cargo capacity.See also: Electric snowbike, Class 1, Class 3

Class 3

Class 3 in the electric snow mobility classification describes a full-size snowmobile of roughly 200 to 350 kilograms, electric or combustion, capable of carrying a passenger or cargo.See also: Snowmobile, Class 1, Class 2

Propulsion and drivetrain

How stored energy becomes forward movement on snow.

Trackalso Tread

A track is a continuous belt of reinforced rubber or composite that rotates against the snow to generate forward thrust. Raised lugs on its outer surface bite into the snow surface, converting motor rotation into forward movement.See also: Lug, Traction, Belt drive

Lug

A lug is a raised protrusion moulded into the outer surface of a track that bites into snow to generate grip. Taller lugs improve traction in deep or soft snow and increase drag and noise on firm surfaces.See also: Track, Traction

Belt drive

A belt drive transmits power from a motor to a track using a flexible belt rather than a chain or gear train. Belt drives run quieter and need less maintenance than chains, at the cost of some efficiency and a risk of slipping under high load.See also: Track, Hub motor

Hub motor

A hub motor is an electric motor built directly into the centre of a rotating component, driving it without a separate gearbox or transmission. Hub motors reduce moving parts and noise, and are used in electric skis to drive a track directly.See also: Torque, Gearless drive

Gearless drivealso Direct drive

A gearless drive connects a motor to the driven component with no intermediate gearing. It eliminates gear noise and a common failure point, at the cost of requiring a motor that produces useful torque at low rotational speed.See also: Hub motor, Torque

Torque

Torque is rotational force, measured in newton-metres (Nm). In an electric ski, torque determines the ability to start moving from a standstill and to climb a gradient, while power determines the speed that can be sustained once moving.See also: Newton-metre, Kilowatt

Newton-metrealso Nm

A newton-metre (Nm) is the standard unit of torque, equal to the force of one newton applied at a distance of one metre from the axis of rotation. Electric ski hub motors are typically rated in the range of tens of newton-metres.See also: Torque

Traction

Traction is the grip between a drive surface and the snow, determining how much of the motor's output becomes forward movement rather than slip. Traction depends on snow firmness, lug design, and how much of the rider's weight sits over the driven surface.See also: Track, Lug, Weight distribution

Weight distribution

Weight distribution describes how a rider's mass is spread across the contact surfaces of a powered ski. Placing a majority of rider weight over the driven surface improves traction; powered-ski patents from as early as 1981 specify targets of 60 to 80 percent over the drive.See also: Traction

Throttle

A throttle is the control a rider uses to set power output. On electric skis it is typically a handheld wireless unit or a control integrated into a ski pole grip, leaving both hands free for poling and balance.See also: Drive mode

Drive mode

A drive mode is a preset power and speed profile a rider can select, trading responsiveness against range. Lower modes limit top speed and acceleration to extend battery life; higher modes do the opposite.See also: Throttle

Selectable engagement

Selectable engagement is a mechanism that lifts a drive track clear of the snow so a ski can glide freely without motor drag. It allows a powered ski to descend or coast as an ordinary ski, and appears in powered-ski patents from 1983 onward.See also: Track, Freewheel

Freewheel

A freewheel is a mechanism that allows a drive component to rotate without turning the motor, so a vehicle can coast without mechanical resistance from its drivetrain.See also: Selectable engagement

Regenerative brakingalso Regen

Regenerative braking converts a vehicle's forward motion back into stored electrical energy by running the motor as a generator, slowing the vehicle while recharging the battery. Its usefulness on snow is limited because a ski's grip is rarely sufficient to absorb meaningful braking force.See also:

Batteries and energy

The constraint that defines the whole category, and the vocabulary for reasoning about it.

Watt-houralso Wh

A watt-hour (Wh) is a unit of energy equal to one watt of power sustained for one hour. Battery capacity is stated in watt-hours, and it is the only figure that allows range claims from different manufacturers to be compared meaningfully.See also: Kilowatt-hour, Battery capacity

Kilowatt-houralso kWh

A kilowatt-hour (kWh) is a unit of energy equal to one thousand watt-hours. Electric snow vehicle batteries range from a few hundred watt-hours for ski-mounted systems to several kilowatt-hours for ridden vehicles.See also: Watt-hour

Kilowattalso kW

A kilowatt (kW) is a unit of power equal to one thousand watts, describing the rate at which energy is used or delivered. Power determines how fast a vehicle can go and how steeply it can climb; energy capacity determines how long it can do so.See also: Watt-hour, Torque

Battery capacity

Battery capacity is the total energy a battery can store, stated in watt-hours or kilowatt-hours. It sets the upper bound on range, but actual range depends on terrain, temperature, rider weight and speed, which is why two products with identical capacity can publish very different range figures.See also: Watt-hour, Cold derating

Cold derating

Cold derating is the reduction in usable battery capacity at low temperatures, caused by slowed chemical reactions and increased internal resistance in lithium cells. It is the single most important and least documented performance factor for any electric snow vehicle, since the entire category operates below freezing.See also: Battery capacity, Battery conditioning

Battery conditioning

Battery conditioning is the practice of bringing a battery to a favourable temperature before use, typically by storing it indoors and installing it immediately before riding. It can substantially increase usable capacity in cold conditions.See also: Cold derating

Swappable batteryalso Hot-swappable battery

A swappable battery is a battery pack a rider can remove and replace in the field without tools, allowing range to be extended by carrying spares rather than by waiting for a charge.See also: Charge time

Cycle life

Cycle life is the number of full charge and discharge cycles a battery can complete before its usable capacity falls below a stated fraction of its original capacity, commonly 80 percent. It is the primary measure of how long a battery will remain useful.See also: Battery degradation

Battery degradation

Battery degradation is the permanent, gradual loss of a battery's usable capacity over time and use. It is accelerated by heat, by charging to full and discharging to empty repeatedly, and by long-term storage at a full state of charge.See also: Cycle life, State of charge

State of chargealso SoC

State of charge is the proportion of a battery's usable capacity currently available, expressed as a percentage. Long-term storage at roughly 50 percent state of charge reduces degradation compared with storing a battery full or empty.See also: Battery degradation

Battery management systemalso BMS

A battery management system is electronics that monitor and protect a battery pack, balancing cell voltages, limiting current, and preventing charging or discharging outside safe temperature and voltage ranges. In cold conditions a BMS may restrict charging entirely until the pack warms.See also: Cold derating, Battery conditioning

Charge time

Charge time is the duration required to restore a battery from a stated low state of charge to a stated high one. Because it converts range into trip planning, a short range paired with a fast charge is a functionally different product from the same range with a slow one.See also: Battery capacity, Swappable battery

Energy density

Energy density is the amount of energy a battery stores per unit of mass, usually stated in watt-hours per kilogram. It is the specific property whose improvement made electric skis buildable, having blocked every powered-ski design from the 1940s to the 2000s.See also: Watt-hour

Snow and conditions

Snow is not one surface. These are the ones that change how a powered ski behaves.

Groomed snow

Groomed snow is a snow surface mechanically tilled and compacted by a grooming machine to produce a consistent, firm running surface. It is the easiest surface for any powered snow vehicle, offering predictable traction and low rolling resistance.See also: Corduroy, Traction

Corduroy

Corduroy is the ridged pattern left on a groomed snow surface by a grooming machine's tiller. It indicates recently groomed, firm, evenly compacted snow.See also: Groomed snow

Powder

Powder is fresh, low-density, uncompacted snow. It is the most difficult surface for a powered ski, because a drive track needs something firm to push against and unconsolidated snow provides little resistance.See also: Traction, Flotation

Wind slab

Wind slab is a dense, cohesive layer of snow formed when wind deposits and packs snow onto a slope. It offers firm traction but is a recognised avalanche hazard when it sits over a weaker underlying layer.See also: Snowpack, Avalanche terrain

Breakable crust

Breakable crust is a frozen surface layer strong enough to briefly support weight before collapsing. It is among the most difficult conditions for both skiing and powered snow travel, because traction and resistance change unpredictably from step to step.See also: Crust, Traction

Crust

A crust is a hardened surface layer of snow formed by melt and refreeze, rain, or wind. A supportive crust provides excellent traction; a crust that fails under load does not.See also: Breakable crust

Snowpack

The snowpack is the full accumulated depth of snow on the ground, composed of layers deposited by successive weather events. Its layered structure determines both avalanche hazard and how a vehicle's weight is supported.See also: Wind slab, Avalanche terrain

Flotation

Flotation is the ability of a ski or vehicle to stay near the surface of soft snow rather than sinking into it, determined by the surface area supporting a given mass. Greater surface area per kilogram improves flotation.See also: Powder, Ground pressure

Ground pressure

Ground pressure is the force a vehicle exerts per unit of contact area with the snow, usually stated in kilopascals. Lower ground pressure means better flotation on soft snow and less impact on the snow surface.See also: Flotation, Snowpack

Base

The base is the compacted lower portion of a snowpack that provides a stable supporting surface. A thin base means obstacles such as rocks and stumps sit close to the running surface.See also: Snowpack

Skiing technique and equipment

Terms carried over from skiing that a reader arriving from outside the sport will need.

Skinningalso Touring, Alpine touring, AT

Skinning is ascending a slope on skis fitted with climbing skins, which grip the snow against backward slide while allowing a forward glide. It is the unpowered method electric skis are most directly an alternative to.See also: Climbing skin, Vertical gain

Climbing skinalso Skin

A climbing skin is a strip of directional-nap fabric attached to the base of a ski that grips the snow against backward movement while permitting forward glide. Skins are removed for the descent.See also: Skinning

Cross-country skiingalso Nordic skiing, XC

Cross-country skiing is travel over flat and rolling terrain on lightweight skis with the heel free, propelled by the skier rather than by gravity. It is the discipline the E-XC name refers to — Electric Cross Country.See also: Classic technique, Skate skiing

Classic technique

Classic technique is a cross-country skiing style in which the skis stay parallel and move forward and back in set tracks, powered by a kick against the snow and a glide on the opposite ski.See also: Cross-country skiing, Skate skiing

Skate skiing

Skate skiing is a cross-country skiing style in which the skier pushes off the inside edge of an angled ski, in a motion resembling ice skating. It is faster than classic technique on firm groomed snow and requires a wider prepared surface.See also: Cross-country skiing, Classic technique

Binding

A binding is the mechanism connecting a boot to a ski. Cross-country and touring bindings leave the heel free to lift; alpine bindings lock the heel down and release under load to reduce injury risk.See also: Tool-free binding

Tool-free binding

A tool-free binding is a binding that can be adjusted or fitted to a boot without tools, allowing changes in the field or with gloves on.See also: Binding

Camber

Camber is the upward arch built into the middle of a ski, so that an unweighted ski touches the snow only near its tip and tail. Camber distributes a skier's weight along the ski and stores energy that returns as rebound.See also: Rocker, Sidecut

Rockeralso Reverse camber

Rocker is an upward curve at the tip or tail of a ski that lifts it clear of the snow earlier than a cambered ski would. Rocker improves flotation in soft snow and makes a ski easier to turn.See also: Camber

Sidecut

Sidecut is the hourglass shape of a ski, narrower at the waist than at tip and tail. When a ski is tipped on edge, its sidecut determines the radius of the arc it naturally carves.See also: Edging, Camber

Edging

Edging is tilting a ski onto its metal edge so it grips the snow and turns. Edging and weight transfer are how an electric ski is steered, since it has no handlebar or steering linkage.See also: Sidecut, Electric ski

Herringbone

The herringbone is a climbing technique in which a skier points the ski tips outward in a V and walks uphill on the inside edges. It is used on gradients too steep for a straight-ahead stride.See also: Skinning

Splitboard

A splitboard is a snowboard that separates lengthwise into two ski-like halves for climbing with skins, then reassembles into a board for the descent.See also: Skinning, Climbing skin

Terrain and measurement

How slopes, distances and climbs are described and compared.

Gradealso Gradient

Grade is the steepness of a slope expressed as a percentage, calculated as vertical rise divided by horizontal distance multiplied by one hundred. A 20 percent grade rises 20 metres over 100 metres travelled horizontally, which is roughly 11 degrees.See also: Degrees of slope, Vertical gain

Degrees of slope

Degrees of slope express steepness as an angle rather than a percentage. Skiing and avalanche literature use degrees; vehicle capability is usually stated as a percentage grade. A 100 percent grade equals 45 degrees.See also: Grade

Vertical gainalso Vert, Elevation gain

Vertical gain is the total height climbed over a route, measured in metres or feet, regardless of horizontal distance. It is the standard unit for comparing the effort or energy cost of an ascent.See also: Grade, Energy per vertical metre

Energy per vertical metre

Energy per vertical metre is the amount of energy required to raise a given mass one metre in elevation, used to compare the cost of an ascent across powered and human-powered methods on a common basis.See also: Vertical gain, Watt-hour

Fall line

The fall line is the most direct downhill path on a slope — the route a ball would roll. It defines the natural direction of descent and the axis skiing technique is oriented around.See also: Grade

Aspect

Aspect is the compass direction a slope faces. It strongly affects snow conditions and avalanche hazard, because sun exposure and prevailing wind differ by aspect.See also: Snowpack, Avalanche terrain

Runout

A runout is the flatter area at the base of a slope where a descent naturally decelerates, and where avalanche debris comes to rest.See also: Avalanche terrain

Skin track

A skin track is the established uphill route packed into the snow by previous parties climbing on skins. Following one is more efficient than breaking a new trail.See also: Skinning, Trail breaking

Trail breaking

Trail breaking is establishing a route through unconsolidated snow that no one has yet travelled. It is substantially more effortful than following a packed track, and is one of the tasks powered snow travel most directly reduces.See also: Skin track, Powder

Access and regulation

The vocabulary land managers use, which decides where any of this is allowed to go.

Motorized use

Motorized use is a land management classification covering travel by any vehicle with a motor. Most existing rules make no distinction by mass, noise, or power source, which is why electric snow vehicles are usually treated identically to combustion snowmobiles.See also: Non-motorized use, Over-snow vehicle

Non-motorized use

Non-motorized use is a land management classification covering human-powered travel only, including skiing, snowshoeing and hiking. Areas designated non-motorized exclude all motor-driven vehicles regardless of size or emissions.See also: Motorized use

Over-snow vehiclealso OSV

An over-snow vehicle is a regulatory term for a motorized vehicle designed to travel over snow on tracks, skis, or low-pressure tyres. It is the category under which most snowmobile access rules are written.See also: Motorized use, Snowmobile

Designated route

A designated route is a specific trail or corridor on which a particular type of travel is permitted, in an area where that travel is otherwise prohibited.See also: Motorized use

Wilderness area

A wilderness area is a category of protected land, in the United States designated under the Wilderness Act of 1964, in which all mechanized and motorized transport is prohibited. This prohibition extends to bicycles as well as motor vehicles.See also: Non-motorized use

Sound pressure levelalso dB, Decibel

Sound pressure level is a measure of sound intensity in decibels, meaningful only when stated with the distance at which it was measured. Noise limits in land management rules are the most common written justification for restricting motorized use.See also: Motorized use

Safety

Winter backcountry terms that apply to powered and unpowered travel alike.

Avalanche terrain

Avalanche terrain is any slope capable of producing an avalanche, along with the runout below it. Slopes between roughly 30 and 45 degrees produce the majority of avalanches, and travel in avalanche terrain requires training, a partner, and rescue equipment.See also: Avalanche transceiver, Runout, Snowpack

Avalanche transceiveralso Beacon, Avalanche beacon

An avalanche transceiver is a body-worn device that transmits a radio signal so a buried person can be located, and switches to receive mode to search for others. It is useful only when every member of a party carries one and has practised with it.See also: Avalanche terrain, Probe, Companion rescue

Probe

A probe is a collapsible pole used to pinpoint the exact location and depth of a person buried in snow after a transceiver search has narrowed the area.See also: Avalanche transceiver, Companion rescue

Companion rescue

Companion rescue is the practice of a party rescuing its own buried members immediately, rather than waiting for organised rescue. Survival probability falls sharply after roughly fifteen minutes of burial, which is far shorter than most external response times.See also: Avalanche transceiver, Probe

Thermal runaway

Thermal runaway is a self-sustaining chain reaction in which a damaged or defective lithium battery cell generates heat faster than it can dissipate it, potentially leading to fire. It is the reason physically damaged battery packs must be removed from service rather than tested.See also: Battery management system, Battery degradation

Cold injury

Cold injury covers frostbite and hypothermia, both risks increased by powered snow travel because a rider generates far less body heat than someone skinning or skiing the same route.See also: Cold derating

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