As well as torro we offer this one in complete build form and frame only option.
As we wanted 420 to be more every day bike and still be rock solid, we used the same headset and bb as in torro to keep the quality
420 frame is more compatible with multispeed hubs so thats the most common choice for it.
It might be 2 speed automatic from SRAM or kick-shift made by Sturmey Archer, also SA cranks are popular in our 420 projects.
All that is controlled with disc front break from Avid in road or mtb version depending on what handlebar/break ever You choose.