Drivetrain
Sprockets, chains, guides, tensioners, and motor pulleys. Gearing changes top speed and hill climb in opposite directions, so check the fitment notes and the gearing calculator before you buy.
Freego eBike Rear Motor Wheel Kit – Pre-Assembled with Rim, Spokes, Tire & Tube
Fits your bike
Freego Electric Bike Conversion Kit with LCD Display
Fits your bike
Freego Nova 3 eBike Drive Pulley Set (Large, Small & Belt Pulley)
Fits your bike
Verified FitDirtyBike 219 Primary Drive Replacement Chain
Verified FitDirtyBike Aluminum Axle Blocks
Verified FitDirtyBike 420 Final Drive X-Ring Chain
Verified Fit
DirtyBike E-Ride Pro 2.0/3.0/SR 219 RK Non-Sealed Chain
Verified FitDirtyBike E-Ride Pro SS 2.0 3.0 420 RK MXU Primary Belt to Chain Conversion
DirtyBike E-Ride Pro SR Primary Belt to Chain Conversion, RK 420 MXU
Verified FitDirtyBike Replacement Slider Chain Guide
Verified FitDirtyBike Surron LBX E-Ride Pro 420 Primary Drive RK MXU Sealed Replacement Chain
Verified FitDirtyBike Surron LBX E-Ride Pro 420 Primary Drive Sealed X-Ring Replacement Chain
Verified FitDirtyBike Surron LBX E-Ride Pro Primary Drive Replacement 219 Rear Driven Sprocket
Verified Fit
DirtyBike Surron LBX Final Drive Front Sprocket, 14T
Pick a trade, not an upgrade
Gearing does not create power, it moves it. Every tooth you add to the rear sprocket buys torque and spends top speed. There is no setting that wins both.
Top speed
Fewer teethTaller gearing. The motor spins slower for the same road speed, so you gain top end and lose the ability to pull away hard or climb steeply. Good on flat open ground, miserable in technical terrain.
- Effect HIGHER TOP SPEED
- Cost LESS TORQUE
- Heat MORE ON CLIMBS
- Best for OPEN, FLAT
In this tier: Smaller rear sprockets
Shop sprocketsBalanced
As deliveredWhat the manufacturer chose, and usually a reasonable compromise. Change the chain and sprockets as a set when they wear — a new chain on worn sprockets destroys itself in a fraction of the time.
- Effect AS DESIGNED
- Cost NONE
- Chain REPLACE AS A SET
- Best for MIXED RIDING
In this tier: Chains, stock-ratio sprockets
Shop chainsTorque and climbing
More teethShorter gearing. Harder acceleration, easier climbing, more wheelie on demand — and a top speed that drops in direct proportion. Also runs the motor cooler on long climbs, which is the argument people forget.
- Effect MORE TORQUE
- Cost LOWER TOP SPEED
- Heat LESS ON CLIMBS
- Best for TIGHT, STEEP
In this tier: Larger rear sprockets
Shop sprocketsChains and sprockets are platform-specific
Pitch, bolt pattern and offset all vary. Filter to your bike and check the tensioner range before ordering a sprocket more than a few teeth away from stock.
Find parts for my bikeHow to actually calculate this
You do not need to guess. The ratio change is proportional and it is arithmetic you can do on your phone.
The ratio
Divide rear teeth by front teeth. Going from a 48T rear to a 58T on the same front is 58 ÷ 48 = 1.21 — about 21% more torque at the wheel and about 21% less top speed. Everything else follows from that one number.
What changes with it
A bigger sprocket usually needs a longer chain, and there is a limit to what the tensioner or the swingarm slot will take. Check the adjuster range before you order, not after.
Chain and sprockets
A chain and its sprockets wear into each other. Fitting a new chain to worn sprockets wrecks the chain quickly and fitting a worn chain to new sprockets wrecks the sprockets. Replace as a set.
The hidden benefit
Shorter gearing lets the motor spin nearer its efficient range on a climb instead of lugging. On a long fire-road ascent that can be the difference between finishing and thermal cutting out.
Drivetrain questions, answered
What does going up ten teeth on the rear actually do?
Do I need a longer chain?
Should I replace the chain at the same time?
Will shorter gearing hurt my range?
How do I know a part fits my bike?
What if it does not fit?
About Drivetrain
Gearing is the cheapest big change you can make to an electric dirt bike, and the easiest one to get wrong. A bigger rear sprocket adds hill torque and low-end pull and takes top speed away in the same proportion; a smaller one does the reverse. Nothing here changes how much power the motor makes, only where it puts it. Run the numbers on the gearing calculator before you buy, or read the 48T vs 58T breakdown for the Light Bee.
Sprockets here are cut from 7075-T6 and hard anodized, in 420 pitch to match the stock chain on Surron and Talaria. Chains are pre-stretched and O-ring sealed so they hold adjustment instead of needing a tug every ride. Tensioners use sealed bearings for the same reason.
Every part shows which bikes it is verified for. Chain slack is set at the tightest point in the suspension travel, not on the stand; the chain care guide covers the 30-second wear check.
Change the ratio, change the bike.
Free US shipping over $99. Every sprocket names the frames it fits.
Shop drivetrain