If you’re wondering how to properly gear your bike to run better, or be more responsive you’re not alone. Gearing your dirt bike is a compromise ratio and as soon as you change your conditions, you might need a new compromise. Here are our best guidelines for this process.
Sprocket size and final driveLets learn some lingo.
Gearing up and gearing down are just not the same; make sure you know the end results of both. You can gear up by using a smaller rear sprocket or a larger countershaft/front sprocket. Gearing up adds more speed and decreases the final drive ratio. You can gear down by using a larger rear sprocket or a smaller front sprocket. Gearing down reduces speed and increases the final drive ratio.
Gearing UP = More Speed
Gearing DOWN = Less Speed
So, what’s the final drive ratio? It just means how many turns the countershaft has to make in order to turn the rear wheel around once (Acceleration). A higher drive ratio corresponds to a lower gearing and more turns of the countershaft for every rotation of the wheel, and a smaller drive ratio corresponds to higher gearing and fewer turns of the countershaft for every rotation of the wheel. Which setup means your engine is working slower? The answer is a higher gear ratio because it turns your wheel with fewer turns of the countershaft.
So, the bottom line is, what are you trying to achieve?
For more bottom end and faster acceleration, use a small countershaft/front sprocket or large rear sprocket. For every 1 tooth that you change on the front sprocket is like changing 3 to 4 teeth on the rear (and that’s true for higher gearing ratios, too). This configuration creates that smaller gearing ratio that works best for tracks with lots of turns, few long straightaways, like Arenacross, and tight trail riding.
For more top end and faster top speed, use a large countershaft/front sprocket or smaller rear sprocket. This creates a taller gearing ratio that’s best for high speed situations without many tight turns like wide open desert racing. Since you get more action from changes to the countershaft, adjust the rear sprocket by just 1 or 2 teeth for a subtle change.
Gearing changes based on conditionsSo, what kind of changes in riding conditions might merit a gearing change? Quite a few actually. Here are some of the principles to keep in mind:
You can physically check whether your chain is worn by measuring how far apart the pins holding the chain together are spaced. This works because there is a “service limit” for how much the chain should stretch; your owner’s manual will tell you what the service limit is.
It’s also time to replace your chain if you see any of these signs:
The bottom lineNo matter where you’re riding, as an experienced racer you’ve probably felt the difference between gearing that was just so-so and gearing that was completely dialed for your track. Fortunately, learning how to decide on gearing gets a lot easier with experience. Understanding the cause and effect of the front and rear sprocket is the most important part; once you’ve got that down, it’s all trial and error.
*Credit Medium.com and BTO Sports