Your One-Stop Motorcycle Chain and Sprocket Guide

Sprockets and chains are some of the many parts that make your motorcycle function. Your front sprocket will rotate with the transmission output shaft, pulling on the drive chain, which in turn rotates the back sprocket, helping the back tire move. The teeth on the sprockets connect to the chain's gaps, creating a tight fit.

If you purchase a new motorcycle, you'll likely have the factory parts to work with, while a used bike may already have sprocket adjustments. And while both setups will undoubtedly work, that doesn't mean it will be the best option for your preferred type of riding. Let's delve into this subject further with our motorcycle chain and sprocket guide.


We've already discussed sprockets and the drive chain and their roles, but those aren't the only terms you'll encounter. Generally, you'll also find people talking about "gearing up" and "gearing down." While both processes involve changing out the sprockets in your bike, they have different impacts on the performance of your cycle.

●  Gearing up can happen when you switch the front sprocket for a smaller size, which will provide more top end speed performance

●  Gearing down can happen when you switch the front sprocket for a larger size, which provides better low-end power and acceleration

It may seem confusing at first because a downsizing a sprocket makes you gear up, while the inverse holds. While it may not be intuitive at first glance, what's essential to understand is that this process isn't necessarily about which sprockets you switch in, but instead how swapping parts impacts an important concept: the sprocket ratio.

Sprocket Ratio

Sprocket ratio refers to the comparison of teeth between the rear and front sprockets. To calculate this value, you want to divide the number of teeth on the back sprocket by the number in the front.

For example, you may have fifteen feet in front and forty-five in the back. To get the ratio, you'd calculate 45/15, which comes out to three. From there, you can then adjust the numbers to get the desired effect you want on the bike. Switching out the front sprocket for a smaller size will increase the ratio (45/14=3.214; gearing up), while trading it for a larger one will have the reverse effect (45/16=2.813; gearing down).

While these examples use changing the front sprocket, you could also trade out the back one (or both) to change the ratio to achieve the desired effect. Commonly, you'll see people discuss their adjustments in terms of pluses and minuses: -2/+3 would indicate decreasing the front by two sizes and increasing the back by three, thus increasing the ratio.

The Impact on Performance

We talked a bit about how swapping sprockets will play into the performance of your bike, but we'll cover it one more time now that we've discussed sprocket ratios:

●  Decreasing the ratio increases acceleration but drops top end speed

●  Increasing the ratio increases top-end speed but reduces acceleration

It's also possible to keep the ratio the same while switching out both sprockets. Generally, this means that the performance of the bike will stay the same, but you can potentially decrease your motorcycle's weight by swapping out for smaller, lighter parts.

Other areas where you'll see performance changes are:

●  Mileage: Higher gear ratios lead to MPG rates dropping, in part due to having higher RPMs, and also potentially due to rapid acceleration on the user end.

●  Speed: When your top speed changes, your speedometer readout becomes inaccurate; dropping the top-speed (gearing down) will make it appear that your bike is going faster than it actually is, and vice versa. You can add mods that will display the correct speed if you so choose.

●  Depending on the type of biking you do, you may want to achieve different things from your sprocket change. Temporarily testing out different ratios can help you get a feel for the type of permanent switch you want to make, and other bikers can also give recommendations.

Changing Sprockets and Chains

Even if you don't want to improve your bike's performance, you'll likely still need to switch these parts out. As you use a motorcycle, the parts wear on each other through use (usually passing each other at a rate of several thousand times in a minute), which will eventually cause issues in performance. Regularly checking the chain and sprockets for signs of wear will give you a clue of when you need to switch them out.

For best results, you want to change the sprocket and chain at the same time. Since they wear down together, you're better off to have a matching set, so everything fits together better from the start. If you use new parts with old ones, you'll likely wear the fresher product out faster.

Thankfully, changing the front and back sprockets are roughly the same level of difficulty, though this can sometimes vary depending on your bike. However, changing out sprocket sizes will mean you need to adjust the chain to fit the new layout best, so there's another benefit to handling the whole process at once.

Aluminum vs. Steel Sprockets

You can find sprockets generally in both these materials, but the performance differences aren't as drastic as they once were. New aluminum products can have life lengths as long as steel ones, and the steel choices can also be about as light as the aluminum ones.

Yes, there are still differences, but you aren't losing out as much on the benefits of one over the other anymore. In the end, you can pick out one based on personal preference. So long as you choose from a trustworthy manufacturer and perform regular maintenance, your sprocket choice should stand up to the test.

Shopping for Sprockets

If you’ve decided that you want to try and adjust your bike’s performance by adjusting the chain and sprockets, you’ll need to get the right equipment to do the job. While replacing the parts isn’t too difficult, without the right sprockets, you may not see the results that you’re aiming for.

Places that sell auto parts can give you options for picking out sprockets in person. Additionally, plenty of online retailers can help if you’re having difficulty locating a certain size—though there’s also the risk of selecting the wrong product since you can’t see it in front of you. In either situation, know the store’s return policy in case you don’t end up with what you need.

If you don’t know the exact sprocket ratio you need, it’s acceptable to buy some cheaper parts to test out the ride, and then invest in more durable versions of your final picks. Even if you do the replacement work yourself, you can still consult a mechanic or other motor bikers for their opinions on which parts to get and recommended ratios.

As you shop, pay close attention to both the sprocket size and that it’s compatible with the chain you need, so there’s no hassle when putting everything together.