What size BMX forks do I need? What is fork offset? BMX fork sizes are measured as shown below.
BMX Fork Dimensions
BMX forks have three main dimensions, as shown in the image above.
Steerer Tube Length: This is the part of the fork that passes through the frame’s headtube. These are typically universal and usually around 165mm long. Longer versions can be useful when running a gyro.
Fork Leg Length: This dimension is typically fixed for all forks, since standard BMX bikes use 20″ wheels. The length is generally consistent across brands, usually around 315mm.
Fork Offset: This is the most important dimension and the one you’ll want to be sure to understand. Forks are offered in a variety of offsets to suit different use cases and riding styles. It’s measured from the center of the fork leg to the center of where the front axle sits in the dropout, and it determines the position of the front wheel on your bike.
BMX Fork Offset
The fork offset affects how the bike feels and responds. Refer to the chart below to learn more about how each offset influences handling and which type of riding it’s best suited for.
| Fork Offset |
Fork Offset |
Riding Style |
|---|---|---|
| 0mm - 15mm | Tiny | Typically flatland riding only |
| 15mm - 20mm | Very Short | Super responsive, twitchy, least stable |
| 20mm - 25mm | Shorter | Very responsive, not too twitchy feeling |
| 25mm - 30mm | Short / Normal | Balanced, responsive and stable feel |
| 30mm - 35mm | Normal / Long | Traditional and very stable feel |
Tips
Generally speaking, newer riders and trail riders may prefer a longer offset for a more stable feel, while street and experienced riders often favor a shorter offset for quicker, more responsive handling.
Some brands now offer adjustable fork offsets, which can be useful since most forks do not allow the offset to be changed. Currently, Kink BMX and Shadow produce forks with this functionality.
Although usually universal, a longer steerer tube can be useful, or even necessary, when using a gyro. A shorter steerer tube may be preferred by riders who want to position their stem as low as possible. This can also be achieved by carefully cutting down the steerer tube.
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