How To Choose Motorcycle Sprockets
Among the easiest ways to give your motorcycle snappier acceleration and feel like it has much more power is a simple sprocket change. It’s a simple job to do, but the hard part 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 the front and rear sprockets. This ratio determines how engine RPM is definitely translated into steering wheel speed by the bike. Changing sprocket sizes, the front or rear, will change this ratio, and therefore change just how your bike puts capacity to the bottom. OEM gear ratios are not always ideal for a given bike or riding style, so if you’ve at any time found yourself wishing you had better acceleration, or found that your motorcycle lugs around at low speeds, you may simply need to alter your current equipment ratio into something that’s more suited to you.
Example #1: Street
Understanding gearing ratios may be the most complex portion of choosing a sprocket combo, so we’ll focus on an example to illustrate the concept. My own bicycle is a 2008 R1, and in stock form it is geared very “high” put simply, geared so that it might reach very high speeds, but experienced sluggish on the lower end.) This caused road riding to end up being a bit of a headache; I had to essentially trip the clutch out an excellent distance to get going, could really only use first and second gear around community, and the engine experienced a little boggy at lower RPM’. What I necessary was more acceleration to make my street riding more enjoyable, nonetheless it would come at the trouble of some of my top rate (which I’ certainly not using on the street anyway.)
So let’s consider the factory setup on my motorcycle, and understand why it felt that way. The inventory sprockets on my R1 are 17 teeth in front, and 45 pearly whites in the rear. Some simple math provides us the gearing ratio: 45/17=2.647. Now I’ve a baseline to work with. Since I want more acceleration, I’ll need a higher equipment ratio than what I’ve, but without going too extreme to where I’ll possess uncontrollable acceleration, or where my RPM’s will be screaming at highway speeds.
Example #2: Dirt
Several of our team members here trip dirt, and they modify their set-ups predicated on the track or perhaps trails they’re going to be riding. Among our staff took his cycle, a 2008 Kawasaki KX450, on a 280-mile Baja ride. As the KX450 is certainly a large four-stroke with gobs of torque over the powerband, it currently has a good amount of low-end grunt. But also for a long trail ride like Baja in which a lot of floor has to be covered, he wished a higher top speed to essentially haul over the desert. His answer was to swap out the 50-tooth inventory rear end sprocket with a 48-tooth Renthal Sprocket to increase speed and get 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, completely different from the big KX450. His preferred riding is on short, jumpy racetracks, where maximum drive is needed in short spurts to clear jumps and electric power out of corners. To achieve the increased acceleration he desired he ready in the rear, from the stock 49-tooth to a 50-tooth sprocket as well from Renthal , increasing his last ratio from 3.769 to 3.846 (quite simply about a 2% increase in acceleration, just enough to fine tune the way the bike responds to the throttle.)
It’s All About The Ratio!
What’s vital that you pulley remember is normally that it’s all about the gear ratio, and I have to reach a ratio that can help me reach my target. There are a variety of methods to do this. You’ll see a lot of talk on the net about heading “-1”, or “-1/+2” and so forth. By using these figures, riders are typically expressing how many teeth they changed from stock. On sport bikes, common mods are to choose -1 in the front, +2 or +3 in back, or a mixture of both. The difficulty with that nomenclature is usually that it only takes on meaning relative to what size the inventory sprockets will be. At BikeBandit.com, we use actual sprocket sizes to point ratios, because all bikes will vary.
To revisit my example, a simple mod is always to move from a 17-tooth in the front to a 16-tooth. That could modify my ratio from 2.647 to 2.813. I did this mod, and I had noticeably better acceleration, making my street riding easier, but it does lower my top rate and threw off my speedometer (that can be adjusted; even more on that afterwards.) 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 options will be limited by what’s practical on your particular bike.
Variations
For a more extreme change, I possibly could have gone to a 15-tooth front? which would produce my ratio specifically 3.0, but I thought that might be excessive for my flavour. There are also some who advise against making big changes in leading, since it spreads the chain drive across less tooth and around a tighter arc, increasing wear.
But remember, it’s about the ratio, and we can change how big is the back sprocket to improve this ratio also. Hence if we went down to a 16-tooth in leading, but concurrently went up to a 47-tooth in the rear, our new ratio would be 2.938; not quite as extreme. 16 in front and 46 in back would be 2.875, a a lesser amount of radical change, but still a bit more than performing only the 16 in front.
(Consider this: since the ratio is what determines how your bike will behave, you could conceivably decrease upon both sprockets and keep carefully the same ratio, which some riders perform to shave excess weight and reduce rotating mass because the sprockets and chain spin.)
The important thing to bear in mind when selecting new sprockets is that it’s all about the ratio. Find out what you possess as a baseline, determine 
what your objective is, and adjust accordingly. It can help to search the net for the experiences of additional riders with the same bike, to discover what combos are the most common. It is also smart to make small adjustments at first, and operate with them for a while on your chosen roads to find if you like how your bicycle behaves with the brand new setup.
FAQ’s
There are a lot of questions we get asked relating to this topic, therefore here are a few of the very most instructive ones, answered.
When deciding on 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 may be the beefiest. Many OEM components will be 525 or 530, but with the effectiveness of a high quality chain and sprockets, there is usually no danger in switching to the lighter 520 setup. Important note: at all times ensure you install elements of the same pitch; they aren’t appropriate for each other! The very best course of action is to buy a conversion kit thus all your components mate perfectly,
Do I have to switch both sprockets simultaneously?
That is a judgment call, and there are differing opinions. Generally, it really is advisable to improve sprocket and chain elements as a set, because they use as a set; if you do this, we advise a high-power aftermarket chain from a high manufacturer like EK ,RK >, and DID
However, oftentimes, it won’t harm to improve one sprocket (usually the front.) If your chain is definitely relatively new, you won’t hurt it to change only one sprocket. Considering that a the front sprocket is typically only $20-30, I recommend changing it as an economical way to test a fresh gearing ratio, before you take the plunge and spend the money to improve both sprockets and your chain.
How does it affect my acceleration and speedometer?
It again is determined by your ratio, but both might generally become altered. Since many riders opt for a higher gear ratio than stock, they’ll experience a drop in best swiftness, 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 adjust the speedometer after modifying the drivetrain.
How will it affect my mileage?
Everything being equal, going to a higher gear ratio will drop your MPGs because you will have higher cruising RPMs for confirmed speed. Probably, you’ll have so much fun together with your snappy acceleration that you might ride even more aggressively, and further reduce mileage. But hey, it’s a bike. Enjoy it and be glad you’re not worries.
Is it much easier to change leading or rear sprocket?
It really is determined by your bike, but neither is normally very difficult to change. Changing the chain may be the most complicated activity involved, therefore if you’re changing simply a sprocket and reusing your chain, that can be done whichever is most comfortable for you.
A significant note: going scaled-down in front will loosen the chain, and you’ll have to lengthen your wheelbase to create up for it; going up in the trunk will also shorten it. Know how much room you need to modify your chain either way before you elect to do one or the other; and if in question, it’s your very best bet to change both sprockets as well as your chain all at once.