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February 4, 2020

HOW TO PICK Motorcycle Sprockets
One of the easiest ways to give your bike snappier acceleration and feel just like it has a lot more power is a straightforward sprocket change. It’s a simple job to do, but the hard part is figuring out what size sprockets to replace your stock ones with. We explain it all here.
It’s ABOUT The Gearing Ratio
Your gearing ratio is, simply put, the ratio of teeth between the front and rear sprockets. This ratio determines how engine RPM is normally translated into steering wheel speed by the bicycle. Changing sprocket sizes, entrance or rear, changes this ratio, and therefore change just how your bike puts power to the bottom. OEM gear ratios are not always ideal for a given bike or riding style, so if you’ve ever found yourself wishing you had better acceleration, or found that your bicycle lugs around at low speeds, you might simply need to alter your current equipment ratio into something that’s more well suited for you.
Example #1: Street
Understanding gearing ratios may be the most complex portion of deciding on a sprocket combo, so we’ll start with a good example to illustrate the idea. My own motorcycle is definitely a 2008 R1, and in stock form it really is geared very “high” put simply, geared so that it might reach very high speeds, but sensed sluggish on the low end.) This caused street riding to become a bit of a hassle; I had to essentially ride the clutch out a good distance to get moving, could really only apply first and second gear around town, and the engine experienced a little boggy at lower RPM’. What I required was more acceleration to make my road riding more enjoyable, but it would arrive at the trouble of a few of my top rate (which I’ certainly not using on the road anyway.)
So let’s look at the factory setup on my motorcycle, and understand why it experienced that way. The stock sprockets on my R1 are 17 teeth in the front, and 45 pearly whites in the rear. Some simple math provides us the gearing ratio: 45/17=2.647. Now I have a baseline to work with. Since I want more acceleration, I’ll need a higher equipment ratio than what I’ve, but without going as well intense 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 trip dirt, and they change their set-ups based on the track or trails they’re going to be riding. One of our personnel took his bike, a 2008 Kawasaki KX450, on a 280-mile Baja ride. Because the KX450 is usually a large four-stroke with gobs of torque across the powerband, it previously has plenty of low-end grunt. But also for a long trail drive like Baja where a lot of ground should be covered, he wished an increased top speed to essentially haul over the desert. His choice was to swap out the 50-tooth share back sprocket with a 48-tooth Renthal Sprocket to improve speed and get a lower cruising RPM (or, regarding gearing ratio, he proceeded to go 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 desired riding is on short, jumpy racetracks, where maximum drive is needed in short spurts to distinct jumps and electricity out of corners. To have the increased acceleration he wanted he ready in the trunk, from the stock 49-tooth to a 50-tooth sprocket as well from Renthal , increasing his last ratio from 3.769 to 3.846 (basically about a 2% upsurge in acceleration, just enough to fine tune what sort of bike responds to the throttle.)
It’s All About The Ratio!
What’s important to remember is certainly that it’s all about the apparatus ratio, and I must reach a ratio that will help me reach my aim. There are many of techniques to do this. You’ll see a large amount of talk on the internet about heading “-1”, or “-1/+2” and so on. By using these figures, riders are typically expressing how many tooth they changed from share. On sport bikes, prevalent mods are to move -1 in front, +2 or +3 in back again, or a blend of both. The problem with that nomenclature is usually that it takes merely on meaning relative to what size the share sprockets will be. At BikeBandit.com, we use precise sprocket sizes to point ratios, because all bikes are different.
To revisit my example, a simple mod would be to proceed from a 17-tooth in leading to a 16-tooth. That could switch my ratio from 2.647 to 2.813. I did this mod, and I acquired noticeably better acceleration, producing my street riding a lot easier, but it did lower my top speed and threw off my speedometer (that may be adjusted; more on that in the future.) As you can plainly see on the chart below, there are a large number of possible combinations to arrive at the ratio you desire, but your alternatives will be limited by what’s feasible on your particular bike.
Variations
For a far more extreme change, I could have attended a 15-tooth front? which would produce my ratio exactly 3.0, but I thought that would be excessive for my style. There are also some who advise against making big changes in the front, since it spreads the chain induce across less tooth and around a tighter arc, increasing wear.
But remember, it’s about the ratio, and we can change the size of the back sprocket to alter this ratio also. Thus if we went down to a 16-tooth in the front, but concurrently went up to a 47-tooth in the trunk, our new ratio will be 2.938; not quite as extreme. 16 in front and 46 in again will be 2.875, a less radical change, but nonetheless a bit more than carrying out only the 16 in front.
(Consider this: since the ratio is what determines how your cycle will behave, you could conceivably decrease about both sprockets and keep the same ratio, which some riders do to shave weight and reduce rotating mass as the sprockets and chain spin.)
The important thing to keep in mind when choosing new sprockets is that it’s all about the ratio. Figure out what you possess as a baseline, determine what your goal is, and change accordingly. It will help to search the web for the activities of other riders with the same cycle, to find what combos are the most common. It is also a good idea to make small adjustments at first, and run with them for a while on your chosen roads to observe if you like how your motorcycle behaves with the brand new setup.
FAQ’s
There are a lot of questions we get asked concerning this topic, hence here are a few of the very most instructive ones, answered.
When choosing a sprocket, what truly does 520, 525, and 530 mean?
Basically, this refers to the thickness of your sprockets and chain (called the “pitch”) 520 is the thinnest and lightest of the three, 525 is in the middle, and 530 is the beefiest. Many OEM components will be 525 or 530, but with the strength of a top quality chain and sprockets, there is generally no danger in switching to the lighter 520 setup. Important note: generally be sure to install elements of the same pitch; they aren’t compatible with each other! The best plan of action is to get a conversion kit hence all of your components mate perfectly,
Do I have to switch both sprockets concurrently?
That is a judgment call, and there are differing opinions. Generally, it really is advisable to improve sprocket and chain pieces as a set, because they dress in as a set; if you do this, we suggest a high-power aftermarket chain from a top company like EK ,RK >, and DID
However, in many cases, it won’t hurt to change one sprocket (usually leading.) If your chain is definitely relatively new, it will not hurt it to change only one sprocket. Considering that a entrance sprocket is typically only $20-30, I would recommend changing it as an inexpensive way to check a fresh gearing ratio, before you make the leap and spend the money to improve both sprockets as well as your chain.
How will it affect my acceleration and speedometer?
It again is determined by your ratio, but both is going to generally end up being altered. Since most riders opt for a higher equipment ratio than stock, they’ll experience a drop in best speed, and a speedometer readout that says they are going faster than they are. Conversely, dropping the ratio will have the contrary effect. Some riders order an add-on module to change 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 should have higher cruising RPMs for a given speed. More than likely, you’ll have so much fun with your snappy acceleration that you may ride more aggressively, and further decrease mileage. But hey, it’s a bike. Have fun with it and be glad you’re not driving a car.
Is it better to change the front or rear sprocket?
It really will depend on your motorcycle, but neither is typically very difficult to change. Changing the chain may be the most complicated activity involved, consequently if you’re changing simply a sprocket and reusing your chain, that can be done whichever is preferred for you.
A significant note: going more compact in the front will loosen the chain, and you’ll have to lengthen your wheelbase to make up for it; going up in the trunk will furthermore shorten it. Understand how much room you will need to adjust your chain either way before you elect to do one or the different; and if in uncertainty, it’s your very best bet to change both sprockets as well as your chain all at one time.