Flexible hinge spine techniques are described. In one or more implementations, a flexible hinge is configured to communicatively and physically couple an input device to a computing device and may implement functionality such as a support layer and minimum bend radius. The input device may also include functionality to promote a secure physical connection between the input device and the computing device. One example of this includes use of one or more protrusions that are configured to be removed from respective cavities of the computing device along a particular axis but mechanically bind along other axes. Other techniques include use of a laminate structure to form a connection portion of the input device.