diff --git a/app/models/bike.rb b/app/models/bike.rb
index 600c516..c29981d 100644
--- a/app/models/bike.rb
+++ b/app/models/bike.rb
@@ -14,7 +14,7 @@ class Bike < ActiveRecord::Base
   belongs_to :bike_status
 
   validates :shop_id, :presence => true, :uniqueness => true, :length => { :minimum => 3 }
-  validates :serial_number, :uniqueness => true, :length => { :minimum => 3 }
+  validates :serial_number, :length => { :minimum => 3 }
   validates :bike_brand_id, :presence => true
   validates :bike_model_id, :presence => true
   validates :color, :presence => true