This video acts as an index to several other crank videos. The "crank" and the "bottom bracket" must have the type of spindle to match. Eg: A square taper crank needs any square taper spindle.

Scope: "Crank Type" refers to the Crank to Spindle Interface, not the Frame interface. These are all cranks fitting to a frame with a BSA shell. But although the Bottom bracket thread is common, only square taper cranks attach to a square taper spindle. ISIS and Octalink cranks fit onto ISIS and Octalink bottom brackets, which are splined spindle interfaces rather than square taper. the three piece attaches to a square taper spindle. eg; ISIS and Octalink cranks fit on an ISIS or octalink bottom bracket which has splines rather than a square taper. But they all still thread into a BSA threaded shell.

 1. Three Piece Self Extracting:
 (Square Taper) He starts with the self extracting cranks. They have a retaining ring fitted for a tool. The one he shows has a 10 mm hex hole, inside is an 8 mm.
 2. Two Piece cranks
 3. Three Piece (non self extracting)
 (three different ones: square taper, ISIS drive, Octalink)
 4. Cottered crank (steel crank and press pin (cotter pin)
 5. One piece cranks (old ccm)

ChatGPT:
 Use ChatGPT to ensure you understand all the terminology. Start with "Important to distinguish the "Frame Standard" as compared to the "Crank to spindle Interface". (BB to frame versus Crank to spindle).

Terminology:
  Retaining Ring
  Pin holes
  BCD (Bolt positions to hold chainring)

 - the typical spec for crank puller is M22 x 1.0

Relevance: All the types described here are within the scope of our "standard bike" concept. All systems can be fitted into a BSA threaded frame shell. So if you bought a used bike which had a Octalink system, you could convert it back to Square taper by putting in a new bottom bracket - crank system.