What size BMX cranks do I need? BMX crank sizes are measured as shown below.
BMX Crank Sizes
BMX crank sizes can be determined by the frame’s chainstay length, the rider’s height, or personal preference. For a general sizing reference, refer to the BMX crank size chart below. For 20″ BMX bikes, crank lengths typically range from 155mm to 180mm, with 160mm to 175mm being the most common.
The chart below is based on the frame’s chainstay length, which helps ensure proper clearance from the rear pegs and provides a balanced feel.
| Chainstay Length |
Rider Feel |
Crank Length |
|---|---|---|
| 12.5″ - 12.75″ | Compact | 160mm |
| 12.75″ - 13.25″ | Short | 165mm |
| 13.25″ - 13.75″ | Standard | 170mm |
| 13.75″ or longer | Long | 175mm |
This alternative chart is based on rider height, which may be useful if you don’t ride pegs or are looking for a better fit based on your height.
| Rider Height |
Rider Height |
Crank Length |
|---|---|---|
| 5’0″ - 5’4″ | 152 - 163cm | 155mm - 160mm |
| 5’2″ - 5’6″ | 157 - 168cm | 160mm - 165mm |
| 5’4″ - 5’8″ | 163 - 173cm | 165mm - 170mm |
| 5’6″ - 6’0″ | 168 - 183cm | 170mm - 175mm |
| 5’8″ - 6’2″ | 173 - 188cm | 175mm - 180mm |
Tips
Generally speaking, shorter cranks are preferred for technical street and park riding due to their more responsive feel and better peg clearance. Longer cranks are preferred for transition and trails riding, as they provide greater stability and a higher top speed.
There’s no right or wrong crank length, it often comes down to personal preference developed over time. But if you’re not sure which size to choose, the charts above are a perfect place to start.
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