Front hub motors are usually the most affordable, due to power rating and simplicity. The most common offerings are 250–350W, which require fewer magnets and less copper wire, holding cost down. There are 500W and 750W available, but price and weight both increase. With no freehub/freewheel to design around, and only one common fork dropout spacing of 100 millimeters, this layout simplifies manufacturing, inventory control, and DIY kit conversions. Flat changes are also slightly easier to execute compared with a rear-drive bike.