Only applies to Royalbaby bikes.
Black for boys/unisex bikes
White for girls bikes
How do I know what size bike do I have?
Check the label on the seat post. eg: RB14B-6B, 14 Here means 14 inch.
Check the tire, 14x2.4, 14 here means 14 inch.
Measure your wheel diameter, 12/14/16/18 inch is the diameter of the wheel size.