BikeShed-1/db/migrate/20130902201853_add_model_to_bike.rb

class AddModelToBike < ActiveRecord::Migration
  def change
    add_column :bikes, :model, :string
    change_column :bikes, :bike_model_id, :integer, :null => true
    Bike.all.each do |bike|
      bike.model = BikeModel.find_by_id(bike.bike_model_id).model
      bike.save
    end
  end
end