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Big or Small BMX Sprockets: Which One to Install

close-up of BMX

Something almost every bicycle has had for quite some time now is the option to switch between different gears. Back in the olden days, bicycles didn’t have that option and they were a bit less versatile. Gears give you more control over a bicycle, but they are also more difficult to ride than say, a BMX bike. Much like older bicycles, a BMX bike makes use of a sprocket that doesn’t allow for a gear change. This may limit BMX bikes when it comes to riding up or down a hill but it gives them a unique ride as well as some health benefits.

Since you have to do more pedalling at times, your balance, coordination, and posture are improved alongside your calves. Brain health, as well as heart health, are also improved by riding a BMX and you get to lose weight too. Your sleep is improved and stress levels reduced while your immune system gets a boost. Although sprockets are not as advanced as they are on regular bicycles they still affect the ride. Just like there are different types of BMX bikes there are also different types of sprockets.

Small vs Big Sprockets

close-up of bmx sprockets

Size plays a big part in how a sprocket affects your ride as it affects the way you handle your BMX. Small BMX sprockets provide more contact surface when in contact with inert objects. This is why a small BMX chain sprocket is ideal if you want to do tricks with your BMX. They make your bicycle more nimble since their form factor makes them light too.

Big sprockets have an advantage over small ones when it comes to durability. Since the sprocket is big, there is less force exerted on the chain. This means fewer broken chains during the lifetime of the sprocket. The teeth of a large sprocket wear out slower since they don’t come in contact as frequently with the chain surface.

How to Install BMX Sprocket

tools for installing bmx sprocket

1. In order to install a new BMX chain sprocket on your bike you need to have it positioned on a bike stand. This will give you room to work with and stability. Once that’s done, get your ratchet and loosen the back wheel.

2. Then, you need to start turning the pedals and at the same time remove the chain from the sprocket. Once you’ve done that, let the chain hang loose and then remove the back wheel.

3. Next, you’ll move on to the actual sprocket and get yourself a 6mm Allen key. You need to put the key on the ratchet and start loosening the top bolt first. Then, loosen the bolt on the bottom (right on the sprocket). Slowly loosen each bolt bit by bit and when you’re near the finish line just remove the sprocket.

4. The sprocket will come out alongside the pedal. This requires you to take off your existing sprocket from the crank arm, usually by removing the bolt holding it in place. Use the same Allen key to remove the bolt.

5. Get your new BMX bike sprocket and align the hole on it with the one on the crank arm. This is where you need to place the bolt holding the sprocket to the crank arm and tighten it with the ratchet. There are typically some spacers that you need to install before you put the sprocket back in place.

6. When putting the sprocket and the crank arm back, put the other pedal up so it’s level with the one that has the sprocket on it. Tighten the bolts you removed from the sprocket earlier by hand and then with the ratchet. Place the back wheel in its place and once done place your chain on the sprocket.

7. Make sure you wind the chain on the sprocket and check the back wheel once again. If the back wheel feels loose, retighten its bolts again and you’re done.

Basic Sprocket Maintenance

lubricating chain on bmx


For a sprocket to last you a long time you need to look after it. Cleaning is the first step towards a longer-lasting sprocket. You need to spray or brush some degreaser onto the cassette (sprocket) regularly, and then leave the degreaser to drip from the sprocket when you apply it. A brush with long bristles should be your main tool when removing dirt, and a rag should be used when cleaning between each sprocket. If the cassette on your BMX is extremely dirty, you’ll need to remove the dirt with some WD40 before you start cleaning the sprocket.


Every time you apply WD40 or clean the sprocket you need to put some lubricant on it. Lubricating the sprocket needs to be done by applying a drop of lube on each chain roller. Once that’s done you need to rotate the pedals backwards for about 20 seconds to allow the lube to spread and penetrate the inside of the chain roller. To make the lubrication process more effective always start applying lube at the joining pin so you’re aware of the place you started. Too much lube is not a good thing either.