HOW TO PICK Motorcycle Sprockets
One of the easiest methods to give your cycle snappier acceleration and feel just like it has far more power is a straightforward sprocket change. It’s a fairly easy job to do, however the hard component is determining what size sprockets to replace your stock types with. We explain it all here.
It’s ABOUT The Gearing Ratio
Your gearing ratio is, to put it simply, the ratio of teeth between your front and rear sprockets. This ratio determines how engine RPM can be translated into wheel speed by the bicycle. Changing sprocket sizes, front side or rear, changes this ratio, and for that reason change just how your bike puts power to the bottom. OEM gear ratios aren’t always ideal for confirmed bike or riding style, so if you’ve ever before found yourself wishing then you’ve got to acceleration, or discovered that your bicycle lugs around at low speeds, you might simply need to alter your current gear ratio into something that’s more well suited for you.
Example #1: Street
Understanding gearing ratios is the most complex portion of deciding on a sprocket combo, so we’ll focus on an example to illustrate the idea. My own motorcycle can be a 2008 R1, and in stock form it really is geared very “tall” basically, geared in such a way that it could reach very high speeds, but felt sluggish on the low end.) This caused road riding to become a bit of a hassle; I had to really drive the clutch out an excellent distance to get moving, could really only make use of first and second equipment around city, and the engine felt a little boggy at lower RPM’. What I needed was more acceleration to create my street riding more enjoyable, but it would come at the expense of a few of my top swiftness (which I’ certainly not using on the street anyway.)
So let’s consider the factory create on my motorcycle, and see why it felt that way. The inventory sprockets on my R1 are 17 tooth in the front, and 45 the teeth in the rear. Some simple math offers us the gearing ratio: 45/17=2.647. Now I’ve a baseline to work with. Since I want even more acceleration, I’ll want a higher gear ratio than what I have, but without going also extreme to where I’ll possess uncontrollable acceleration, or where my RPM’s will end up being screaming at highway speeds.
Example #2: Dirt
Several of our team members here ride dirt, and they transform their set-ups based on the track or trails they’re going to be riding. Among our personnel took his bicycle, a 2008 Kawasaki KX450, on a 280-mile Baja ride. As the KX450 is a major four-stroke with gobs of torque across the powerband, it already has lots of low-end grunt. But for a long trail trip like Baja where a lot of floor has to be covered, he sought a higher top speed to really haul across the desert. His option was to swap out the 50-tooth stock rear end sprocket with a 48-tooth Renthal Sprocket to increase speed and get yourself a lower cruising RPM (or, regarding gearing ratio, he went from 3.846 right down to 3.692.)
Another one of we members rides a 2003 Yamaha YZ125 a light, revvy two-stroke, very different from the big KX450. His preferred riding is on short, jumpy racetracks, where maximum drive is needed in short spurts to obvious jumps and vitality out of corners. To get the increased acceleration he desired he geared up in the rear, from the stock 49-tooth to a 50-tooth sprocket as well from Renthal , increasing his final ratio from 3.769 to 3.846 (in other words about a 2% increase in acceleration, just enough to fine tune the way the bike responds to the throttle.)
It’s ABOUT The Ratio!
What’s vital that you remember is usually that it’s all about the gear ratio, and I have to arrive at a ratio that will help me reach my aim. There are a number of ways to do that. You’ll see a large amount of talk on the internet about heading “-1”, or “-1/+2” etc. By using these numbers, riders are usually expressing how many tooth they changed from inventory. On sport bikes, common mods are to move -1 in front, +2 or +3 in back, or a combination of the two. The issue with that nomenclature is certainly that it only takes on meaning in accordance with what size the inventory sprockets happen to be. At BikeBandit.com, we use actual sprocket sizes to indicate ratios, because all bikes are different.
To revisit my case in point, a 
simple mod is always to choose from a 17-tooth in the front to a 16-tooth. That could transform my ratio from 2.647 to 2.813. I did so this mod, and I got noticeably better acceleration, producing my street riding easier, but it did lower my top quickness and threw off my speedometer (that can be adjusted; more on that afterwards.) As you can see on the chart below, there are always a multitude of possible combinations to arrive at the ratio you need, but your alternatives will be limited by what’s possible on your particular bike.
Variations
For a more extreme change, I could have gone to a 15-tooth front? which would generate my ratio precisely 3.0, but I thought that might be excessive for my style. Additionally, there are some who advise against making big changes in leading, since it spreads the chain push across less the teeth and around a tighter arc, increasing wear.
But remember, it’s about the ratio, and we are able to change the size of the rear sprocket to improve this ratio also. And so if we transpired to a 16-tooth in the front, but concurrently went up to a 47-tooth in the rear, our new ratio would be 2.938; not quite as extreme. 16 in the front and 46 in backside would be 2.875, a fewer radical change, but nonetheless a bit more than doing only the 16 in the front.
(Consider this: for the reason that ratio is what determines how your bike will behave, you could conceivably go down on both sprockets and keep the same ratio, which some riders perform to shave fat and reduce rotating mass as the sprockets and chain spin.)
The important thing to keep in mind when selecting new sprockets is that it’s all about the ratio. Find out what you have as a baseline, know what your target is, and change accordingly. It will help to find the net for the experience of different riders with the same cycle, to look at what combos will be the most common. It is also smart to make small changes at first, and operate with them for a while on your chosen roads to look at if you want how your cycle behaves with the new setup.
FAQ’s
There are a lot of questions we get asked about this topic, hence here are some of the very most instructive ones, answered.
When choosing a sprocket, what really does 520, 525, and 530 mean?
Basically, this identifies the thickness of your sprockets and chain (called the “pitch”) 520 may be the thinnest and lightest of the three, 525 is in the middle, and 530 may be the beefiest. Various OEM components will be 525 or 530, but with the strength of a top pulley quality chain and sprockets, there is generally no danger in switching to the lighter 520 setup. Important note: usually be sure to install parts of the same pitch; they aren’t compatible with each other! The very best course of action is to get a conversion kit consequently your entire components mate perfectly,
Do I have to switch both sprockets as well?
This is a judgment call, and there are differing opinions. Generally, it really is advisable to change sprocket and chain components as a set, because they put on as a set; if you do this, we advise a high-strength aftermarket chain from a top brand like EK ,RK >, and DID
However, oftentimes, it won’t harm to change one sprocket (usually the front.) If your chain is normally relatively new, it will not hurt it to change only one sprocket. Considering that a front side sprocket is normally only $20-30, I recommend changing it as an inexpensive way to test a new gearing ratio, before you make the leap and spend the amount of money to improve both sprockets and your chain.
How does it affect my swiftness and speedometer?
It again is determined by your ratio, but both will generally be altered. Since many riders opt for a higher equipment ratio than stock, they’ll experience a drop in leading quickness, and a speedometer readout that says they are going faster than they happen to be. Conversely, dropping the ratio will have the opposite effect. Some riders buy an add-on module to adapt the speedometer after modifying the drivetrain.
How will it affect my mileage?
Everything being equal, likely to a higher gear ratio will drop your MPGs because you will have larger cruising RPMs for a given speed. More than likely, you’ll have so much fun together with your snappy acceleration that you may ride more aggressively, and further lower mileage. But hey, it’s a bike. Have fun with it and become glad you’re not driving a car.
Is it easier to change the front or rear sprocket?
It really depends on your bicycle, but neither is typically very difficult to change. Changing the chain may be the most complicated process involved, therefore if you’re changing just a sprocket and reusing your chain, that you can do whichever is preferred for you.
An important note: going scaled-down in front will loosen the chain, and you’ll need to lengthen your wheelbase to make up for it; going up in the trunk will moreover shorten it. Understand how much room you need to adjust your chain either way before you elect to do one or the other; and if in hesitation, it’s your best bet to change both sprockets and your chain all at once.
Compound pulley
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