Everything from suspension to the type of gas used determines bike response, how well you ride, and in terms of racing, how you compete for the podium.
Fine tuning a dirt bike can wreak havoc on a rider's patience as it involves a seemingly endless cache of parts, hours of testing and deciding on upgrades. You, of course, can ride stock, easy enough - but many, if not most riders, once the tinkering starts, realize a better joy of riding a dirt bike.
One aspect to fine tuning revolves around (no pun intended) the drive or drivetrain which primarily consists of the chain and sprockets, and chain and sprockets go together like peanut butter and jelly.
Choosing the correct chain and sprockets setup helps with flow, power to the ground and acceleration. In fact, dialing in this gearing for the Motocross track or riding trails often gives your dirt bike a whole new feel.
Understanding Gearing Ratio
The gearing or drive ratio influences torque, top speed and acceleration. Each of these affected by the number of "teeth" on the front and rear sprockets.
A higher gearing ratio means more rear sprocket teeth and less in the front. Higher gearing delivers more torque, quicker acceleration and lower top speed.
Conversely, a lower gearing ratio puts more teeth up front and less in back. This setup produces less torque and slower acceleration but higher top speed. Those who ride pedal bikes with multiple gears can practice this by changing the gears from the smaller to larger front and rear sprockets.
Front sprockets generally have 12 to 15 teeth while rear sprockets have 45 to 53 teeth.
How To Decide on the Best Dirt Bike Gearing
Gearing for Motocross
Since we live and breathe Motocross, let's start with the best chain and sprocket setup for racing track. But get a lay of the land first. Lots of hills, cornering and long straightaways help determine whether you decide on more teeth in the front or rear.
For example, use a lower gearing ratio (more teeth upfront) for a faster track that embraces a wide-open throttle. That gives you higher top-end speed. A twisty track requires faster acceleration to pull out of corners so you want a higher gearing ratio.
Don't go tooth crazy though. If your stock bike comes with a 13/49 gearing ratio try 13/48 or 14/49 for lower or 13/50 or 12/49 for higher. Tinker from there, but usually you don't need to drop or add three or four teeth in the front or rear for Motocross.
Gearing for Woods and Trail Riding
Tight winding trails with steep hill climbs call for lots of torque. For this, you might need to lose or gain a few teeth. To get better throttle response for these types of riding conditions try two or three more teeth on the rear sprocket or drop one up front. So, for a stock gearing ratio of 13/49, change to either 13/52 or 12/49.
Mechanics Tip: Removing one tooth from the front sprocket equals adding two to three in the rear.
Gearing for Supermoto
Supermoto converts your average dirt bike to a street screaming machine thus demands a whole different gearing setup. Find the necessary top speed by dropping two or three teeth on the rear sprocket and/or adding one or two to the front. Try 15/45.
Gearing for Pit Bikes / Mini Bikes
Whether you ride for fun or race pit bikes, you can try lots of options like a 14/47 ratio for speed or 13/49 to get super quick acceleration.
OK, so what about the chains?
Dirt Bike Chain Types
We have several articles on chain types (see below) but to summarize:
- Standard Chain: Lightweight and less expensive. The beginner rider and even weekend warrior can get away with using a standard chain. Just be wary of wear and tear. These unsealed chains require diligent post-ride cleaning and plenty of chain lube.
- O-Ring Chain: Middle of the road chains feature sealed rubber rings that grease the inside links. More expensive than standard, longer lasting and a great choice for those trying to fine tune their drive but do expect slightly more drag.
- X-Ring Chain: Expensive, durable chains also with sealed rubber rings offering less drag than O-ring.
A couple of new styles exist but the above remain the most popular. Also, consider chain pitch. Most dirt bikes use 520 chains, but some big-bore or adventure bikes use wider 525 or 530.
To really dial in the best chain for your dirt bike, if you ride a 125cc or bigger engine, try the durability and tensile strength of an O-ring or X-ring chain.
Steel vs. Aluminum Sprockets
- Steel sprockets: Long-lasting, heavy, great for rear or front on any bike but always use steel for the front sprocket.
- Aluminum sprockets: Lightweight and wears faster but ideal for those looking anywhere and everywhere for shedding racing weight.
- Hybrid sprockets: Steel teeth with aluminum core. Expensive but gives strength and durability. Supersprox owns the market on this for now.
Finding the right gearing ratio takes time. Expect to try different setups and as your career - if you so choose - progresses expect to own multiple front and rear sprockets and chains. You might find after the first Moto the need to gear up or down so you can complete better in Moto 2. So, make the switch!
Mechanic's Tip: Want a new dirt bike without buying a new dirt bike? Change the gearing!
And remember, when the time comes, change your sprockets and chains together.
Related Shopping Categories
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