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In short – YES, they do matter. Not only that, where you put them matters too.

Tune in to discover:

  • How a sprocket’s size is determined
  • What a “sprocket ratio” is – and how to determine it
  • How sprocket sizes matter


Hello, and welcome to another episode of 30-minute Motorcycling – a podcast for those riders who are at the beginning of their own Dual Wheel Journey, where you’ll discover something new about how your motorcycle, moped, or scooter works – in less than 30 minutes.


And let’s talk about sprockets. They seem so simple, don’t they – just a pair of toothed wheels that interlock with the drive chain so that power can be transferred from the transmission to the rear wheel.


But these sprockets come in a variety of sizes, and to answer the question in the title for this episode – yes, sprocket sizes DO matter.


In this episode, you’ll find out more about sprocket sizes – from how sizing is determined to how to calculate sprocket ratios and, of course – what happens if you replace a smaller sprocket with a bigger one.


But first things first – how is the size of a motorcycle sprocket determined?


Contrary to what you might have believed, it’s not the diameter of the sprocket that determines its size – it’s how many teeth it has.


The more teeth, the larger the sprocket size.


So what about “sprocket ratios,” then? 


If you’ve listened to episode 35, you’ll know about gear ratios – which is the difference in size between the two gears for the input and output shaft. One of these gears is smaller than the other one and therefore rotates much faster.


Why am I bringing this up in an episode about sprockets? Because the same principle applies here, too – one of the sprockets is smaller than the other one, so it rotates faster than the bigger sprocket.


And calculating your sprocket ratio is all a matter of dividing the number of teeth on your front sprocket by the number of teeth on your rear sprocket.


So for example, if you have a front sprocket with 20 teeth, and a rear sprocket with 60 teeth, your sprocket ratio is equal to 1:3[one by three] since 20/60=0.3.


But first, do you know where your front sprocket is?


It’s not easy – unlike the rear sprocket, the front sprocket isn’t out in plain sight. Rather, it’s hidden on the output shaft of the transmission case.


This means that if you want to access your front sprocket, you’ll have to remove the transmission cover or a special cover known as the “front sprocket cover.” In some cases, you might even have to remove the entire wheel.


Now that we’ve covered how to determine your sprocket size, how to calculate your sprocket ratios, and even where the front sprocket is, let’s talk about the thing you’re probably here for:


“How do sprocket sizes matter – what does a bigger sprocket do on a motorcycle?”


Well, it can increase acceleration or top speed – it depends on where you put the bigger sprocket.


Have you put it at the front? Then, your bike can reach a higher top speed – at the expense of slower acceleration.


And if you’ve put the bigger sprocket at the rear – the roles, and the results are reversed – now, your acceleration will be much faster, and instead, it’s your top speed (and certainly your fuel efficiency) that suffer.


One last thing to know about sprocket sizes is that they are not the be-all-and-end-all – no matter if you’re trying to achieve faster acceleration or top speed by swapping out your sprockets, they are just a part of the proverbial chain-driven equation.


You also need to consider the chain itself – in particular, chain size. And if you’d like to know more about chain size, episode 49 of 30 Minute Motorcycling has the information you want.


Either way, that’s the end of this episode about sprocket sizes and why they matter.


I hope you enjoyed listening and, above all, that you learned something new. 


Until next time, keep your helmet on and your eyes on the road. Bye!