How Electric Dirt Bikes Work, From Battery To Rear Wheel

The Power Path, Battery To Wheel

A gas dirt bike burns fuel to push a piston, then uses a clutch and a five- or six-speed gearbox to match the engine's narrow power band to road speed. An electric dirt bike skips all of that. Energy flows from the battery to an inverter, from the inverter to the motor, and from the motor through one fixed reduction and a chain to the rear wheel. When you roll off, the flow can run backwards.

Press the steps, then try the sliders. Throttle sends energy to the wheel. Close it with engine braking turned up and the arrows reverse. Hold a high power setting for a while and watch the motor heat up.

The Battery Stores DC Energy

The battery is a pack of lithium cells that stores energy as direct current. Its capacity is measured in kilowatt-hours (kWh), which is energy, the electric version of tank size. Stark lists 7.2 kWh at 420 V for the current Varg MX. The battery is the heaviest single part of the bike, so where it sits controls the handling; Stark places the battery, motor and its cooling radiator low and central under the seat.

Published specs have changed as the bike moved from launch to production, so always quote the version:

Battery care, charging habits and storage are covered in our electric dirt bike maintenance guide.

The Inverter Turns DC Into Three-Phase AC

An electric motor of this kind runs on three-phase alternating current. The inverter is a set of fast electronic switches that chop the battery's DC into three AC waves, at whatever frequency and strength the motor needs at that moment. Frequency sets motor speed. Current sets torque. That is why the inverter, or controller, is the part that really decides how hard the bike pulls. Stark builds the inverter inside the motor case.

The Motor And Its Torque Curve

Below its base speed, the motor can make full torque from a standstill. Above base speed, the controller weakens the magnetic field so the motor can keep revving, and torque falls off as rpm rises. A gas engine is the opposite shape. It makes little torque near idle, builds to a peak somewhere in the middle, then falls away near the rev limit.

The Varg's motor is liquid cooled in an aluminum case. Our four-stroke engine guide shows where a gas engine's torque comes from, if you want the other side of the comparison.

Why Electric Dirt Bikes Have No Gearbox Or Clutch

A gas engine needs a clutch to get moving from zero rpm and a gearbox to keep its narrow power band in use. A motor that makes full torque from a standstill and revs high does not. One fixed reduction through a normal 520 chain covers the whole speed range, according to Stark.

Stark founder Anton Wass explained the rider's side on the Gypsy Tales podcast. As an average amateur, he said, "I'm always in the wrong gear," and riding motocross means synchronizing about ten things at once; take away gears and clutch and three of them are gone. Sam Moore, testing a Varg for the same podcast, said that with no clutch to slip he had to keep his body forward under power, which is the position coaches want anyway.

Power Is Software

On a gas bike, displacement and engine tuning set the power. On an electric bike, the controller decides how much current flows. Stark sells the Varg MX in 60 and 80 hp versions and says power is adjustable from 10 to 80 hp. At the 2021 launch it advertised up to 100 power maps. These are peak claims; Stark does not publish a continuous power figure.

Moore said the 60 hp setting he rode was pitched as a stock 450 and that a factory 250 makes about 60 hp too. Those are a rider's estimates, not dyno numbers. Mapping and setup choices are covered in electric dirt bike setup.

Regenerative Engine Braking

When you roll off the throttle, the motor can work as a generator. The wheel drives the motor, the inverter converts that back to DC, and some energy returns to the battery. The drag you feel is the electric version of engine braking. Stark lets riders set it from free rolling up to something close to a gas 450. Moore described the range as zero, like a coasting mountain bike, to 100, which feels like a 450.

Heat And Run Time: How Long Do Electric Dirt Bikes Last?

Heat is the real limit on an electric drivetrain. Motors, inverters and cells lose power when they get hot, so the controller derates, cutting power to protect them. That is why sustained output is lower than the peak horsepower figure, and why the Varg's motor is liquid cooled.

How long a charge lasts depends on how hard you ride. Stark claims about 38 minutes for a pro on hard-pack motocross up to several hours of trail riding per charge, and about two hours to charge at 240 V. Treat those as manufacturer claims and log your own numbers. If a bike starts cutting power early, our electric dirt bike troubleshooting guide covers heat and warning states.

How Electric Dirt Bikes Got Here

• 2014. KTM's Freeride E range, the first electric off-road bikes from a major manufacturer, with a removable 2.6 kWh battery and 16 kW peak power.
• 2017. The Alta Redshift MX claims 40 hp from a 5.8 kWh pack at $14,995. In December, Josh Hill beats Ricky Carmichael on one at the Geneva Supercross.
• 2018. Alta stops operations on October 17 after Harley-Davidson pulls out of a deal. Wass says Alta's failure is what pushed him to start Stark.
• 2019. KTM announces the SX-E 5 kids' bike, and Honda shows its CR Electric prototype in Tokyo.
• 2021. Stark reveals the Varg. Wass says Stark sold 800 bikes in the first six hours and about 5,000 in six weeks.
• 2023. First customer Vargs ship from Barcelona on April 25. Trey Canard races Honda's CR Electric in the All Japan IA1 class.
• 2024. Jack Brunell wins the British Arenacross Pro title on a Stark, which Stark calls the first title for an electric bike against gas bikes. Stark announces the road-legal Varg EX enduro.
• 2025. Yamaha shows its YE-01 electric motocross prototype at EICMA.

For how the gas bikes evolved over the same seventy years, see the history of dirt bikes.

Where Electric Dirt Bikes Race

Racing is still deciding where electric bikes belong. The FIM ran its first E-Xplorer World Cup for electric off-road bikes in 2023. In 2024 MXGP's promoter announced a separate electric class, MXEP, from 2026, and Stark objected. Wass also says SuperEnduro once banned electric bikes 24 hours before a race after Stark had built a team. In 2026 Stark won the FIM SuperEnduro manufacturers' title.

In the US, Davey Coombs told Gypsy Tales that AMA classes are built around 250 and 450 cc, and an electric bike is "this third thing". He says an AMA official put it simply: "we need to build a box."

What Still Needs Service

An electric dirt bike has no oil changes, no valve checks and no top end. The chain, sprockets, brakes, tires, wheel and linkage bearings and suspension still wear exactly as they do on a gas bike. Stark publishes hour-based service intervals; we list them in the Stark Varg MX maintenance schedule and the Varg EX checklist. MotoMind tracks those tasks by hours and by date and shows each one as upcoming, due or overdue, and its GPS ride tracker can add ride time for you.

FAQ

How do electric dirt bikes work?

A battery stores energy as DC. An inverter converts it to three-phase AC and controls how much current reaches the motor. The motor drives the rear wheel through one fixed reduction and a chain. On roll-off, the motor can work as a generator and send energy back to the battery.

Why don’t electric dirt bikes have gears?

An electric motor makes full torque from a standstill and keeps pulling to high rpm, so one fixed ratio covers the whole speed range. A gas engine makes little torque at low rpm and needs a clutch and gears.

How long do electric dirt bikes last on a charge?

It depends on how hard you ride. Stark claims about 38 minutes for a pro on hard-pack motocross up to several hours of trail riding for the Varg, with about two hours to charge at 240 V.

How much horsepower does a Stark Varg have?

Stark sells 60 and 80 hp versions of the Varg MX and says power is adjustable from 10 to 80 hp. These are peak manufacturer claims.

How much does a Stark Varg weigh?

Stark claimed 110 kg with a 6.0 kWh battery at the 2021 launch. The first production bikes in 2023 were listed at 118 kg with 6.5 kWh, and the current Varg MX page lists 118 kg with 7.2 kWh.

Do electric dirt bikes have engine braking?

Yes, through regenerative braking. The motor works as a generator when you roll off. Stark lets riders set it from free rolling up to a feel close to a gas 450.

Do electric dirt bikes need maintenance?

Yes. There are no oil changes or valve checks, but the chain, sprockets, brakes, tires, bearings and suspension still wear and need regular service.

What was the first electric dirt bike from a major manufacturer?

KTM’s Freeride E range in 2014, with a removable 2.6 kWh battery and 16 kW of peak power.