Frame

The frame determines a bike's type and geometry.

Frames have attachment points that allow or limit which parts you can use.

Frames come in different materials and designs, which determine rider position and tire clearance.

Headtube size

Determines the headset, fork, and stem options.

VIntage bikes: 1"

Modern bikes: 1 1/8"

Seatpost diameter

Various sizes.

Rear dropouts

Dropout widths