CHOOSING Motorcycle Sprockets
Among the easiest ways to give your bicycle snappier acceleration and feel like it has a lot more power is a straightforward sprocket change. It’s a fairly easy job to do, but the hard component is determining what size sprockets to displace 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 usually translated into steering wheel speed by the cycle. Changing sprocket sizes, the front or rear, changes this ratio, and for that reason change just how your bike puts capacity to the ground. OEM gear ratios are not always ideal for a given bike or riding design, so if you’ve at any time found yourself wishing you had better acceleration, or discovered that your bike 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 is the most complex part of deciding on a sprocket combo, so we’ll focus on a good example to illustrate the idea. My own cycle is certainly a 2008 R1, and in share form it is geared very “tall” in other words, geared so that it could reach high speeds, but experienced sluggish on the low end.) This caused road riding to always be a bit of a headache; I had to really drive the clutch out an excellent distance to get going, could really only apply first and second equipment around area, and the engine sensed a little boggy at lower RPM’. What I necessary was more acceleration to create my street riding more enjoyable, but it would arrive at the expense of some of my top acceleration (which I’ 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 share sprockets on my R1 are 17 pearly whites in the front, and 45 tooth in the trunk. Some simple math gives us the gearing ratio: 45/17=2.647. Now I have a baseline to work with. Since I want more acceleration, I’ll desire a higher equipment ratio than what I have, but without going too severe to where I’ll possess uncontrollable acceleration, or where my RPM’s will become screaming at highway speeds.
Example #2: Dirt
Several of our team members here trip dirt, and they adjust their set-ups based on the track or trails they’re going to be riding. One of our personnel took his motorcycle, a 2008 Kawasaki KX450, on a 280-mile Baja ride. As the KX450 is normally a big four-stroke with gobs of torque over the powerband, it currently has a lot of low-end grunt. But for a long trail trip like Baja in which a lot of surface should be covered, he sought an increased top speed to really haul over the desert. His remedy was to swap out the 50-tooth stock rear end sprocket with a 48-tooth Renthal Sprocket to improve speed and get a lower cruising RPM (or, regarding gearing ratio, he gone from 3.846 down to 3.692.)
Another one of our team members rides a 2003 Yamaha YZ125 a light, revvy two-stroke, very different from the big KX450. His preferred riding is on brief, jumpy racetracks, where optimum drive is needed in short spurts to very clear jumps and electric power out of corners. To achieve the increased acceleration he wished 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 the way the bike responds to the throttle.)
It’s ABOUT The Ratio!
What’s important to remember is definitely that it’s all about the gear ratio, and I have to reach a ratio that will help me reach my aim. There are a variety of methods to do that. You’ll see a large amount of talk on the internet about going “-1”, or “-1/+2” and so on. By using these numbers, riders are usually expressing how many the teeth they changed from share. On sport bikes, common mods are to proceed -1 in front, +2 or +3 in back again, or a mixture of both. The difficulty with that nomenclature is that it takes merely on meaning in pulley accordance with what size the inventory sprockets are. At BikeBandit.com, we use precise sprocket sizes to indicate ratios, because all bikes are different.
To revisit my case in point, a simple mod is always to head out from a 17-tooth in the front to a 16-tooth. That would modify my ratio from 2.647 to 2.813. I did so this mod, and I had noticeably better acceleration, making my street riding a lot easier, but it performed lower my top speed and threw off my speedometer (which may be adjusted; even more on that in the future.) As you can see on the chart below, there are always a large number of possible combinations to arrive at the ratio you really want, but your options will be tied to what’s possible on your own particular bike.
Variations
For a more extreme change, I could have gone to a 15-tooth front? which would produce my ratio exactly 3.0, but I thought that might be excessive for my preference. Additionally, there are some who advise against producing big changes in leading, since it spreads the chain force across less tooth and around a tighter arc, increasing wear.
But remember, it’s about the ratio, and we are able to change how big is the rear sprocket to alter this ratio also. Consequently if we transpired to a 16-tooth in the front, but concurrently went up to 47-tooth in the rear, our new ratio will be 2.938; not quite as extreme. 16 in front and 46 in back again would be 2.875, a fewer radical change, but still a little more than performing only the 16 in the front.
(Consider this: because the ratio is what determines how your bike will behave, you could conceivably decrease upon both sprockets and keep the same ratio, which some riders do to shave pounds and reduce rotating mass because the sprockets and chain spin.)
The important thing to bear 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 objective is, and modify accordingly. It can help to search the web for the experiences of other riders with the same cycle, to look at what combos are the most common. Additionally it is smart to make small alterations at first, and run with them for a while on your chosen roads to discover if you like how your bike behaves with the brand new setup.
FAQ’s
There are a great number of questions we get asked relating to this topic, and so here are some of the very most instructive ones, answered.
When deciding on a sprocket, what 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 centre, and 530 may be the beefiest. Many OEM components will be 525 or 530, but with the strength of a top quality chain and sprockets, there is usually no danger in switching to the lighter 520 setup. Important note: generally be sure to install components of the same pitch; they are not compatible with each other! The very best plan of action is to get a conversion kit and so your entire components mate perfectly,
Do I have to switch both sprockets simultaneously?
This is a judgment call, and there are differing opinions. Generally, it is advisable to improve sprocket and chain components as a collection, because they have on as a set; if you do this, we suggest a high-durability aftermarket chain from a high brand like EK ,RK >, and DID
However, oftentimes, it won’t harm to improve one sprocket (usually leading.) If your chain is certainly relatively new, you won’t hurt it to improve only one sprocket. Considering that a entrance sprocket is normally only $20-30, I recommend changing it as an inexpensive way to check a new gearing ratio, before you take the plunge and spend the amount of money to change both sprockets as well as your chain.
How will it affect my rate and speedometer?
It again is determined by your ratio, but both definitely will generally end up 
being altered. Since the majority of riders decide on a higher equipment ratio than stock, they will knowledge a drop in top velocity, and a speedometer readout that says they are going faster than they will be. Conversely, dropping the ratio will have the contrary effect. Some riders buy 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 bigger cruising RPMs for a given speed. More than likely, you’ll have so much fun with your snappy acceleration that you may ride even more aggressively, and further lower 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 depends upon your cycle, but neither is normally very difficult to improve. Changing the chain may be the most complicated process involved, consequently if you’re changing only a sprocket and reusing your chain, that you can do whichever is most comfortable for you.
An important note: going scaled-down in the front will loosen the chain, and you’ll have to lengthen your wheelbase to create up for it; increasing in the rear will similarly shorten it. Understand how much room you have to adapt your chain in any event before you elect to do one or the additional; and if in question, it’s your very best bet to improve both sprockets as well as your chain all at one time.