The Prologue Fork Mount is the ultimate entry-level fork mount. The Prologue's single-wall aluminum bike tray supports bikes with wheelbases up to 48" and tires widths up to 2.6". The Prologue's stainless steel 9mm skewer with an oversize lever makes the design rugged, secure and easy to use. The Thule Prologue's dual-lock design locks your bike to the carrier and your carrier to the rack (locks are sold separately - see below). The Prologue's sleek and stylized mounting head fits most disc and suspension combinations with standard 9mm axles. Plus, the Prologue is approved for carbon fiber forks. The Prologue's uniquely designed head has the ability to adapt to both square and round load bars. The Thule Prologue is a great rack at a great price.