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 fairly easy job to do, but the hard part is determining what size sprockets to replace your stock ones with. We explain everything 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 translated into wheel speed by the cycle. Changing sprocket sizes, the front or rear, will change this ratio, and for that reason change just how your bike puts capacity to the ground. OEM gear ratios are not always ideal for confirmed bike or riding style, so if you’ve ever found yourself wishing you had better acceleration, or discovered that your cycle lugs around at low speeds, you might should just 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 part of deciding on a sprocket combo, so we’ll start with a good example to illustrate the idea. My own bike can be a 2008 R1, and in stock form it really is geared very “tall” put simply, geared so that it could reach very high speeds, but felt sluggish on the low end.) This caused road riding to end up being a bit of a headache; I had to essentially trip the clutch out a good distance to get moving, could really only apply first and second equipment around city, and the engine experienced just a little boggy at lower RPM’. What I required was more acceleration to make my road riding more enjoyable, nonetheless it would come at the trouble of a few of my top acceleration (which I’ certainly not using on the road anyway.)
So let’s consider the factory create on my bike, and understand why it sensed that way. The share sprockets on my R1 are 17 teeth in the front, and 45 teeth in the rear. Some simple math provides us the gearing ratio: 45/17=2.647. Now I have a baseline to utilize. Since I want more acceleration, I’ll desire a higher equipment ratio than what I’ve, but without going as well severe to where I’ll possess uncontrollable acceleration, or where my RPM’s will always be screaming at highway speeds.
Example #2: Dirt
Several of our team members here drive 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 definitely a huge four-stroke with gobs of torque across the powerband, it already has lots of low-end grunt. But also for a long trail ride like Baja where a lot of floor needs to be covered, he required an increased top speed to essentially haul over the desert. His solution was to swap out the 50-tooth inventory backside sprocket with a 48-tooth Renthal Sprocket to improve speed and get a lower cruising RPM (or, in conditions of 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 recommended riding is on short, jumpy racetracks, where optimum drive is needed in short spurts to clear jumps and ability out of corners. To achieve the increased acceleration he desired he ready in the trunk, from the stock 49-tooth to a 50-tooth sprocket also 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 All About The Ratio!
What’s important to remember is normally that it’s 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 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 tooth they changed from inventory. On sport bikes, common mods are to move -1 in front, +2 or +3 in again, or a combo of both. The issue with that nomenclature is definitely that it only takes on meaning relative to what size the share sprockets happen to be. At BikeBandit.com, we use precise sprocket sizes to indicate 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 change my ratio from 2.647 to 2.813. I did so this mod, and I possessed noticeably better acceleration, producing my street riding a lot easier, but it do lower my top velocity and threw off my speedometer (which can be adjusted; even more on that soon after.) As you can plainly see on the chart below, there are a multitude of possible combinations to arrive at the ratio you wish, but your options will be limited by what’s likely on your particular bike.
For a more extreme change, I could have attended a 15-tooth front? which would generate my ratio precisely 3.0, but I thought that would be excessive for my tastes. There are also some who advise against producing big changes in the front, since it spreads the chain force across less the teeth and around a tighter arc, increasing wear.
But remember, it’s all about the ratio, and we can change the size of the back sprocket to alter this ratio also. And so if we went down to a 16-tooth in leading, but concurrently went up to 47-tooth in the trunk, our new ratio would be 2.938; not quite as extreme. 16 in the front and 46 in backside will be 2.875, a much less radical change, but still a bit more than carrying out only the 16 in front.
(Consider this: since the ratio is what determines how your motorcycle will behave, you could conceivably decrease in both sprockets and keep the same ratio, which some riders do to shave excess weight and reduce rotating mass because the sprockets and chain spin.)
The important thing to keep in mind when selecting 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 motorcycle, to look at what combos are the most common. It is also smart to make small adjustments at first, and run with them for some time on your chosen roads to discover if you like how your bike behaves with the new setup.
There are a great number of questions we get asked relating to this topic, 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 may be 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 effectiveness of a top quality chain and sprockets, there is normally no danger in switching to the lighter 520 setup. Important note: at all times be sure to install pieces of the same pitch; they are not compatible with each other! The best plan of action is to get a conversion kit so your entire components mate perfectly,
Do I have to switch both sprockets concurrently?
This is a judgment call, and there are differing opinions. Generally, it really is advisable to improve sprocket and chain components as a arranged, because they wear as a set; if you do this, we suggest a high-power aftermarket chain from a high manufacturer like EK ,RK >, and DID
However, in many cases, it won’t hurt to change one sprocket (usually leading.) If your chain can be relatively new, it will not hurt it to improve only one sprocket. Due to the fact a entrance sprocket is typically only $20-30, I would recommend changing it as an economical way to test a fresh gearing ratio, before you make the leap and spend the amount of money to improve both sprockets as well as your chain.
How does it affect my swiftness and speedometer?
It again depends on your ratio, but both definitely will generally end up being altered. Since the majority of riders opt for a higher equipment ratio than stock, they will encounter a drop in best velocity, and a speedometer readout that says they go faster than they will be. Conversely, dropping the ratio will have the contrary effect. Some riders invest in an add-on module to modify the speedometer after modifying the drivetrain.
How does 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 become glad you’re not driving a car.
Is it easier to change the front or rear sprocket?
It really will depend on your bike, but neither is typically very difficult to change. Changing the chain is the most complicated process involved, hence 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 more compact in the front will loosen the chain, and you’ll have to lengthen your wheelbase to create up for it; increasing in the trunk will moreover shorten it. Understand how much room you should change your chain in any event before you elect to do one or the other; and if in hesitation, it’s your very best bet to change both sprockets as well as your chain all at one time.
HOW TO PICK Motorcycle Sprockets