Gearing Calculator
Sprocket / final drive ratio calculator
Compare front / rear combos and see the speed vs torque trade-off
This free motorcycle gearing calculator compares two front / rear sprocket combinations and shows exactly how the final drive ratio change affects top speed, wheel torque and engine RPM. Built for enduro, motocross, dual-sport and trail riders running KTM, Husqvarna, GasGas, Yamaha, Honda, Beta and Sherco bikes.
Quick gearing cheat-sheet
- +1 tooth on the rear (or -1 at the front) → more torque, snappier acceleration, lower top speed.
- -1 tooth on the rear (or +1 at the front) → less torque, longer pulls in each gear, higher top speed.
- One front tooth roughly equals three rear teeth — front changes are big.
- Large changes can need a longer / shorter chain and an axle re-position. Check the chain marks before ordering.
How the gearing calculator works
A sprocket gearing calculator compares two front/rear tooth combinations and shows exactly how the change affects top speed and wheel torque. The final drive ratio is simply rear sprocket teeth divided by front sprocket teeth — a 13/50 setup is 3.85:1, a 14/48 setup is 3.43:1. Drop the rear or raise the front and the ratio gets smaller, so the bike pulls a taller gear: higher top speed but less torque at the rear wheel. Do the opposite and the bike gets snappier off the bottom but signs off earlier in top gear.
Sprocket math — the rules of thumb every rider should know
- One front tooth ≈ three rear teeth. Because the front sprocket is so much smaller, a single front-tooth swap changes the final drive far more than a single rear-tooth swap. A -1 front change typically equals a +3 rear change.
- +1 tooth on the rear (or -1 on the front) shortens gearing. More acceleration, more wheel torque, snappier out of corners, lower top speed. The classic tight-trail / single-track move.
- -1 tooth on the rear (or +1 on the front) lengthens gearing. Less wheel torque, longer pulls in each gear, higher top speed. Better for fast desert / fire-road / open enduro loops.
- Chain length matters. Big gearing changes can mean adjusting the rear-axle position or swapping in a longer / shorter chain. Check the chain-tension marks before ordering sprockets.
- Front sprocket size affects chassis behaviour. Going down a tooth at the front tightens the chain angle relative to the swingarm pivot and can make the bike feel more lively over bumps. Going up usually settles the chassis.
Common stock gearing — modern enduro and motocross bikes
Always check your owner's manual or VIN sticker — these are typical factory-spec sprocket combos, not gospel.
- KTM 250 / 300 EXC, EXC TPI: 13/50 (3.85:1) — most popular alternative is 14/50 for fast loops.
- KTM / Husqvarna / GasGas 350-500 4-stroke enduro: 14/52 (3.71:1).
- Husqvarna TE 250i / 300i: 13/50 (3.85:1).
- GasGas EC 250 / 300: 13/48 or 13/50 depending on year.
- Yamaha YZ250 / YZ250X: 14/50 (3.57:1) — race riders often run 13/50 for tighter MX tracks.
- Honda CRF250R / CRF450R: 13/49 and 13/49 respectively.
- Beta RR 250 / 300 2T, Xtrainer: 13/49 (RR) and 12/50 (Xtrainer).
- Sherco SE 250 / 300 Factory: 13/48.
Choosing the right gearing for your terrain
- Tight single-track, technical enduro, hard-enduro: Shorter gearing — typically +1 or +2 teeth on the rear, or -1 at the front. Helps the bike chug in 2nd / 3rd without needing the clutch as much.
- Mixed cross-country / GNCC / hare scrambles: Usually stock or +1 on the rear. You want torque out of corners but still need to top out on power-line straights.
- Motocross / supercross: Track-by-track. Tighter tracks favour shorter gearing; sand and fast outdoor tracks favour taller gearing.
- Desert, dunes, fast fire-road: Taller gearing — -1 on the rear or +1 at the front. Lets the engine breathe in top gear instead of buzzing at the rev limiter.
- Dual-sport / road-going enduro: Taller gearing keeps the engine relaxed on the highway between trail sections.
Gearing calculator — frequently asked questions
What does the final drive ratio actually tell me?
Final drive ratio is rear sprocket teeth divided by front sprocket teeth. It is the number of countershaft turns required for one full rear-wheel turn. A higher number means more wheel torque and lower top speed; a lower number means less wheel torque and higher top speed at any given engine RPM.
Should I change the front or the rear sprocket?
For small adjustments (+/- 1 ratio step) the rear is the usual choice — it is cheaper, chain length usually still fits, and the change is gentler. The front sprocket is faster to swap and offers bigger steps: one front tooth roughly equals three rear teeth. Many riders go up a front tooth for fast desert riding, and down one rear tooth for tighter trails.
Will a sprocket change wear my chain faster?
Not directly — a sprocket change does not accelerate chain wear if the chain is properly tensioned and aligned. What hurts a chain is running it with an old / cupped sprocket, an incorrect length, or after a big change that pulls the axle to the limit of its adjustment. Replace sprockets and chain together when any of the three are worn out.
Do I need a new chain when I change sprockets?
Small changes (+/- 1 rear tooth) usually fit the existing chain. Bigger changes — for example going from 13/50 to 14/52 — can need a chain that is 1 or 2 links longer. Always test-fit the new sprockets with the chain at recommended tension before riding.
What gearing do KTM, Husqvarna and GasGas enduro 2-strokes come with?
Modern KTM 250/300 EXC, Husqvarna TE 250i/300i and GasGas EC 250/300 typically ship with 13/50 (3.85:1). The most common alternatives are 13/52 for harder, tighter terrain and 14/50 (or 14/52) for fast, open trails.
Does shorter gearing wear the engine more?
A bit — shorter gearing means the engine spins faster for the same ground speed, so total engine revolutions per ride go up. The effect is small for sensible changes (+/- 1 or 2 teeth on the rear). It only becomes meaningful with extreme gearing or with a lot of top-gear highway riding.