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As much credit as the chain for chain-drive motorcycle gets, the sprockets play a big role, too – but what is a “sprocket,” anyway?

And if you need to replace your chain, do you know where to look to find the chain sizing?

Tune in to discover:

  • What a “sprocket” is – and two places on your motorcycle where you can find one
  • How you can determine your chain sizing EASILY
  • How to decipher the digits in the chain sizing number sequence



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.


If you’ve got a motorcycle or even a moped with chain drive, the chain itself usually gets the most attention – but what about the sprocket? That plays a big role in the chain drive mechanism too.


And while we’re on the topic of big, do you know how to determine the size of your chain?


That’s what this episode is all about, so let’s just dive in.


First of all – what’s a sprocket?


If you look at the center of your rear wheel, you’ll see a small toothed wheel that the chain (or more specifically, the chain’s rollers) wraps around.


This toothed wheel is the “sprocket,” and in addition to the one you can see at the rear wheel, there’s also another one attached to the transmission’s output shaft – which you can’t see much of because it’s covered up by the transmission case.


If you’d like to know more about the transmission and how it works, please check out episode 35 of 30-minute motorcycling – there’s even an explanation of what a “gear ratio” is.


But I digress, the critical thing to know about sprockets is that they go hand-in-hand with chains. Without a sprocket, the chain is useless, and without a chain, the sprocket is useless.


It’s for this reason that you should replace sprockets and chains together. A worn-out sprocket will wear out a brand new chain faster, and vice versa.


If you do need to replace your chain, you must know the chain sizing. Fortunately, this is easy – it’s often stamped somewhere on a side plate on the chain itself in the form of three digits, such as “535.”


That’s all well and good, but what do these numbers mean?


The first digit in the number sequence – “5” in our case, is the chain’s pitch – i.e. the distance between two pins, expressed in one eighth on an inch.


And the remaining two digits are of the width of the chain rollers (i.e. a series of rollers connected by links) expressed in one-eightieth of an inch. 


So that’s how you can read and decipher chain sizing, as well as what a sprocket does for a chain drive.


If you’re interested in hearing more about the differences between chain and belt drive, please check out episode 21 of the 30 Minute Motorcycling Podcast.


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