Method 1: Take a look at the old seat tube, sit on the pipe wall with a seal, the number of types
Method 2: If the stamp can not be seen clearly, the circumference can be measured. Diameter 25.4 circumference 8cm diameter 27.2 circumference 8.5cm diameter 28.6 circumference 9cm diameter 30.8 circumference 9.7cm
Method 3: sitting tube is gone, it can only measure the bicycle caliper, caliber,
Method 4: The easiest, send a picture of the whole car bike! We have plenty of experience to determine for you!
The length of this product is 350 mm

And the folding car used 500 mm