How Sprockets Affect Speed on Motorcycles And Why


It doesn’t matter if you’re a racer; if you’re just into trails riding your dual-sport, your bike can be geared differently to your performance needs. Not only on a dirt bike but also the street. 

If you are on a sportbike, if you ride a touring bike, if your motorcycle has a chain and sprocket or even a belt, changing the gearing can make a big difference.

I ride the track a lot, and depending on which track you go to, your bike can be geared differently. 

Glen Helen vs. milestone is a different track. You would gear down at Glen Helen, and you would kind of gear up at milestone. We’ll explain that in a second.

So why would you want to change the gearing? All these bikes come from the factory set up to get a certain mile per gallon or hit EPA emission standards.

Often, your motorcycle might be a little bit slow on the bottom end, but they have a nice top-end. 

So it will be set up for cruising speeds if you’re looking at a bike made for riding on the streets.

Most dirt bikes are geared fairly neutral from the factory. Meaning that if you do take it to a dirt bike track, you might want a little bit more bottom end, which means you’d add a couple of teeth to the rear.

Going to the desert, you might want a little bit more top speed, which means you’d bring down the teeth in the rear.

When we’re talking about changing your gearing, it’s about changing your front and rear sprocket’s size to get the ultimate performance you’re looking for.

There are calculators online that will give you the specific gear ratio if you give them the front wheel, the rear wheel, and your chain link.

What you want to do, and this depends on what you’re riding, you want your bike’s best performance gear ratio.

Three Ways To Change Gear Ratio 

There are three ways to do it You’ve got a mild change, you’ve got a medium change, and you’ve got a relatively drastic change.

The mild change would be going two teeth up in the rear. That’s going to give you a better bottom end, and it’s going to take a little bit off the top end but not a whole lot. It gives you a little bit more punch out of the corners. 

If you wanted to go a little bit more dramatic, you’d go one tooth down in the front. That’s going to be the equivalent of going three teeth up in the rear. It’s a happy medium of that next step.

How To Get More Top-End Speed On A Motorcycle

What we desert guys like to do is an inexpensive way to gear your bike for the desert. 

We like to go up one tooth in the front, which is equivalent to down three teeth in the rear, increasing our top speed.

When you go up one tooth in the front, what’s going to happen? Are the bikes going to feel a little bit slower off the line, but you’re going to be able to rev up higher to those higher RPMs and have higher top speed when you’re out there with a throttle pin wide open.

The gears will be longer. You’re going to be able to run the gears out for a longer period before you have to shift, versus going up a bunch of teeth in the rear. 

Your gears will be real short, but the bottom end is going to be right there.

When it comes to gear ratios, gearing up and gearing down, it cannot be very clear. 

When you put a larger sprocket on your bike, that’s called gearing down, but if you’re adding more teeth and making it larger, wouldn’t it be called gearing up? You’re going up in teeth, but essentially you’re gearing down.

Let’s say you’re running you’re stock set of sprockets. The front sprocket has to go around a certain number of times for the rear sprocket to make one revolution.

When I say I’m going to gear down, I like to think of it as I’m gearing down my top speed but giving myself some more oomph out of the corners.

When you’re gearing up, what you’re doing is you’re looking for that more top-end. 

You’re looking to go smaller sprocket in the rear, so you get longer pulls out of each gear and a higher top speed.

Other than performance, why would you change your chain and sprocket? Well, I think there are only two reasons.

Number one. If your stock stuff is beat to crap, it’s probably time for a new set of chains and sprockets. Number two, If you want some bling. 

From the factory, sprockets come all bright and shiny, so if you want to have a killer-looking setup that either matches your bike or contrasts your bike dollar, that’s a great way to go as well.

The third reason is the weight. A factory sprocket we weighed recently weighed in at 1.8 pounds. It was heavy.

While we tested an aftermarket sprocket and that weighed in at 0.8 pounds.

That’s saving a pound of weight off your rotating mass just by changing the sprockets. And when you’re racing, weight is horsepower.

So why was the factory sprocket so much heavier? The reason is that it’s made of steel. 

Most street bikes will come with a steel sprocket, but a common upgrade is to go aluminum on sportbikes to save that weight to reduce the rolling resistance.

Most dirt bikes come with an aluminum sprocket, but it’s not hard anodized. 

ProTaper and rental and other sprocket companies like to hard-anodize their aluminum sprocket. 

It keeps them lightweight, but it also adds some strength, and strength means longevity and more miles or hours that you’re going to get out of your components.

Styles Of Chains

Chains come in three basic sizes. You have a 520, and a 525 and a 530 are the most common. That goes for all big bikes, which would be 125CC and up. 

The smaller bikes like 85s and 65s tend to use 420 size chains, or 415. In addition to chain sizing, we also have how the chain is made. 

We have chains that are standard change with no o-rings. We have o-rings, we have X rings, there are lots of different options for putting a chain on your motorcycle.

There are different colored chains as well. You’ve got your standard chain, and you’ve got red blue-and-green chains. 

Personally, I like the gold chain. It’s made with different materials, and it’s going to last the longest.

Do You Need To Change Chain And Sprocket At The Same Time?

A very common question that we get is, “Should I replace just my chain, or do I need to replace my chains and sprockets at the same time?”

It’s very important to change your chain and your sprockets at the same time because that’s going to give you the longest life for your parts.

The reason for that is that the chain and sprockets are set up where the tolerance is between the chain and the sprocket are very tight. 

Now, if you take a worn-out chain and put that on a new sprocket, it’s going to beat the sprocket up and wear it out fast.

Conversely, if you take a chain and try to put that onto an old set of sprockets, what’s going to happen is there will be a lot of slop there, and that chain will get torn up quickly.

If you were to put a worn sprocket next to a new sprocket, you would see the top of the teeth would be super thin compared to how thick they were original. 

You would also see that they’re scooped and scalloped and leaning one direction, definitely worn down way more than the original.

So, if you were to put a brand-new chain onto the old sprocket, the grooves would be so large that the chain would wiggle within in wearing the chain out faster than usual.

Buying the chain and sprocket as a kit gives you your correct sprockets for the correct gear ratios you’re looking for and a chain all-in-one convenient kit. 

You’ll notice that the kit prices are usually a little bit cheaper than buying all the parts individually. 

I like the kits because they’re set up for the year model specifically, so you can’t go wrong.

If you’re looking to gear up, go ahead and add a tooth in the front if you have the room or take away a couple of teeth in the rear.

If you’re looking to gear down, you would take a tooth away from the front or add some in the rear.

Does Gearing Increase Torque?

How To Get More Top-End Speed On A Motorcycle

Ultimately it determines how your engine speed translates to how fast you can go road speed and how much torque there is at the rear tire.

Before we get into nuts and bolts of gearing changes, let’s talk the lingo. When someone refers to a bike gearing as being tall or high, that means you’re going to have a higher top speed but at the expense of outright acceleration.

If someone says the gearing of the bike is low or short, that means you’re going to have brisk acceleration but at the expense of your top speed. Here’s the confusing part, though. 

A larger ratio, say 3.10 correlates to shorter gearing, whereas a smaller ratio, say 2.7 represents taller gearing. 

This all goes back to how many times that front sprocket has to rotate to turn the rear sprocket, and thus, the wheel.

How To Increase Speed With Sprockets

The good news is that while crunching the numbers and looking at the actual gear ratios is helpful, it is not needed.

All you need to consider is what the tooth count on your motorcycle is right now, and that is usually printed right on the side of the sprocket.

You have to figure out how you want to change the tooth count to change your bike’s performance. 

If you want better acceleration, let’s say because you add a small displacement bike or ride predominantly in the city.

What Does A Bigger Front Sprocket Do? 

On really tight canyon roads, you’re going to lower your gearing by either reducing the tooth count on the front sprocket or adding teeth to the rear sprocket.

If, however, you want to get better gas mileage or lower your cruising RPM like we want to do with our Kawasaki Versys, you’re going to need to raise your gearing. Either by reducing the tooth count on the rear or adding teeth to the front. 

For the most part, people tend to gear their bikes shorter since motorcycles today come with excessively tall gearing. 

Even if the gearing on your bike feels like it’s way out of line for the way you ride, the reality is, you’re probably not going to have to make a big gearing change to notice a big difference.

In general, folks will change the front sprocket by one, maybe two teeth, and then alter the rear by saying two or three teeth max. 

Big gear plates, like one with fifty-three teeth, exist, but the only people you’re going to see using them are stunt riders or hill climbers.

If you change your bike’s gearing, even by just one tooth, you’re changing the sprocket diameter, so you’re going to need to readjust your chain.

Most gearing changes of just a tooth or two can be accommodated by the swingarm adjustment, but you don’t want to screw with your bike’s wheelbase too much. 

If you go with the big sprocket, you’re probably going to find that you need a longer chain.

Also, if you’ve got a fair amount of miles on your current drivetrain components, It’s a good idea to replace everything as a set so that it wears evenly. 

Throwing a new sprocket at an old worn-out chain is going to chew it up in a hurry.

Another thing to consider when changing your bike’s gearing is how it might affect your speedometer. 

Most motorcycles register the transmission speed, so if you adjust the final drive gearing, you’re going to throw off the calculation that the ECU is doing.

If you’ve got an older motorcycle with a cable-operated front wheel speed sensor: you should be in the clear, but otherwise, you might want to consider getting a speedo healer or a similar calibration device.

If you are a little short of cash or want to experiment to see how a gearing change will affect your bike’s performance, the cheapest and easiest thing to do is replace the countershaft sprocket.

The front sprocket is cheaper, usually about twenty or thirty bucks. It’s easier to replace since it’s held on with less hardware.

One tooth difference on the front will make a bigger change to your final drive ratio than one tooth on the rear sprocket.

What Does Increasing Rear Sprocket Size Do?

Rear sprockets are more expensive, and they’re also a little bit more difficult to replace since you have to remove your rear wheel. 

Finally, when it comes to buying replacement sprockets, you can go the OE route, which will probably be a stamped steel affair.

Or you can turn to the aftermarket, where there’s a variety of aluminum and steel sprocket options.

Aluminum is a lot lighter, but it doesn’t have great durability, so it might not be a good option for street riders that log a lot of miles. 

That’s where a product like the super sprockx stealth sprocket has a durable steel chainring and rivets it to a lightweight aluminum carrier, so you get the best of both worlds.

In case you’re wondering if your bike has a belt drive or a shaft drive, you’re pretty much stuck with the final drive gear ratio that you’ve got.

Changing the final drive on those bikes isn’t impossible, but it isn’t easy and can be very expensive. 

Whereas, if you have a chain-driven bike, you can swap out your whole Drive chain in about an hour and for just a couple hundred bucks.

There you go, info on how your final drive ratio affects your motorcycle performance and some stuff to think about and look out for when you decide to change your sprockets.

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