Originally Posted by
CliffordK
You can "weld" most plastics, and CF is basically fiber reinforced plastic. However, simple welding it would be extremely weak at the joints without additional reinforcement. I have a CF frame with round tubes and aluminum lugs, but the lugs are cast, of course,
One definition of welding is to "combine to form an effective whole", so yes carbon fiber bicycle can be considered to be "welded". I think for the purpose of this discussion and as answering the OP, welding refers to the use of blowtorch or electrical arc to heat metal so that multiple parts join together. Under that definition, carbon fiber bicycles are not welded.