I've Got No Control

Help !! can anyone out there recommend a contact or dealer/agent that deals with a manufacturing company called Peerless of China, I bought two ebikes from an auction, but they are missing the speed controls!! I think they are some kind of variable resistor or Potentiometer and I know where it is supposed to be attached to the motor control board, but I don't know what ohmic value of pot, please help!!

The bikes were a bargain and brand new but they are just pedal bikes at the moment!!