How do you tell the size of existing BMX cranks on a bike?

Question

How do you tell the size of existing BMX cranks on a bike?

Answer 1

measure...got to no if it is a 3 pc crank or 1 pc

Answer 2

A couple of ways.  (1) Look on the inside of the crank arm.  Odds are you'll find an  number.  (2) Using a clothiers tape or a ruler with millimeters and/or centimeters measure from the center of the bottom bracket to the center of the hole for the pedal.  Common sizes are 155 to 165 (kids) and 170 to 180 (adult).  BMX cranks tend to run a little longer.  5'5 to 5'10" would probably run about 175 to 180.  6' or over 180 to 185s.

Answer 3

oops sorry that is a sprocket!!! my bad sorry :(

Answer 4

count the teeth