module_gear.rb

require 'pry'
module SomeFramework
  class Gear
    attr_reader :chainring, :cog, :wheel

    def initialize (args)
      args = defaults.merge(args)
      @chainring = args[:chainring]
      @cog       = args[:cog]
      @wheel     = args[:wheel]
    end

    def ratio
      chainring / cog.to_f
    end

    def gear_inches
      ratio * wheel.diameter
    end

    def defaults
      {:chainring => 40, :cog => 18}
    end
  end

  class Wheel
    attr_reader :rim, :tire

    def initialize(rim, tire)
      @rim  = rim
      @tire = tire
    end
      
    def diameter
      rim + (tire * 2)
    end

    def circumference
      diameter * Math::PI
    end  
  end 
end

module GearWrapper
  def self.gear(args)
    SomeFramework::Gear.new(args[:chainring],
                            args[:cog],
                            args[:wheel])
  end
end

GearWrapper.gear(
  :chainring => 52,
  :cog       => 11,
  :wheel     => Wheel.new(26,1.5)).gear_inches