BMX Sprockets Guide
BMX sprockets are generally a universal fit. They will come with a 24mm hole bored in the centre with 2 spacers to reduce this to either 22mm or 19mm and so will fit all different crank spindles. The only exception to this is spline drive BMX sprockets where you need to make sure it is compatible with your cranks.
What sprocket do i need for my BMX?
BMX sprockets fall into one of two design categories, either a regular sprocket or guard sprocket. Guard BMX sprockets have either a replaceable nylon piece or alloy machined with the sprocket to protect the teeth and chain. These are generally just used by street BMX riders who wish to protect the sprocket and chain when doing grinds. The nylon guard will provide less resistance if caught during grinds and can be replaced if broken of worn out, whereas the alloy guard provides tougher protection but may stick more if caught when grinding and once worn out means your whole sprocket needs replacing. It's hard to say what is the best BMX sprocket as it can come down to personal choice and liking the brand or aesthetic of the sprocket.
What size sprocket is best for BMX?
When choosing you BMX sprocket size your style of riding will help you choose how many teeth to go for. Originally when BMX started gearing was at a ratio of 2.75. This is worked out by dividing the number of teeth on your sprocket by the amount on your driver or freewheel on your rear wheel. Since then BMX has evolved and riders run ratios of up to 3.44 or above. The higher the ratio the faster you will be able to go but it will be harder to get going from a standstill. Almost all rear wheels will now come with a 9 tooth driver and so the standard gearing would now be a 25 tooth sprocket and 9 tooth drive – 25/9 = 2.77. This is ideal for starting out in BMX as seen on all entire level complete bikes and also the preferred gearing of a lot of BMX street riders. You'll often see this referred to as bmx sprocket 25t with the t indicating the amount of teeth. If you like to ride fast then a 28 tooth, referred to as bmx sprocket 28t or perhaps an even larger BMX sprocket like 30t may be required. Generally sizes above this like 44t are for racing to increase the ratio so you can still generate more speed through pedalling when already moving quickly on your BMX.