Often people think the Flying Pigeon and other Chinese Roadster Brands are just copies of Raleigh Roadsters. Why is Raleigh singled out and not some Dutch or French roadster of which there were many? I suspect this is because Raleigh roadsters were one of the most popular bikes in the world, and most casual bicycle historians don't know much else.
Of course, the FP factory in Tianjn maintains that the Flying Pigeon was an original design conceived in 1950. But is that the truth? Lets examine the products.
Let's start with the Bottom bracket. Raleigh was well known for using unique 26TPI threading in their bottom bracket shell. Raleigh shells were also a unique sizes typically between 71mm and 76mm which was quite oversized. Otherwise they used a cottered crank and spindle with loose ball bearings. That part is not so unique.
What does the FP use? Like Raleigh it does use cottered cranks and spindles. But the bottom bracket shell is sized at a more conventional 68mm and the threading is standard "B.S.C." threading, not Raleigh threading. This was part of a deliberate rationalization. Before the Communists came to power there were many bicycle factories in China, manufacturing to different standards: Japanese, British, Continental etc. In order to maximize output and simplify production, these standards were done away with in favor of a single BSC standard. This can also be seen elsewhere on the bike.
Again Raleigh liked to use their own specific threading in the eyelets where the mudguards attach to the frame. The FP uses metric fasteners only. The axle nuts may be an exception.
It is true that the body work on an FP and Raleigh will interchange. but this is also is true of ANY roadsters built to use 26" or 28" wheels which was somthing of a global standard before and during the 1950's. The fenders of both brands are sized to 26" or 28" wheels, but the manner of attachments are different. Again Raleigh roadsters use a fender bracket which attaches the fender to the frame. The FP in contrast uses a very simple "l" tab to attach the fenders at both the front and the rear for 26" frames, and a direct bolt to the frame for the rear 28" fender.
Furthermore, the package rack on a Raleigh,or other European roadster, attach to the seat stays via a clamp. This type of attachment is actually quite weak and not appropriate for China where passengers often ride side saddle on the back, and of course heavy loads are normal. Instead ALL Chinese roadster package racks bolt directly to the seat post. A much simpler and stronger solution, in keeping with the objectives of making a durable bike that is easy to build and maintain.
Raleigh roadsters were famous for their elegant and (almost) unique centerpull brake rods. This solution included a very pretty hinge point which straddles the frame. While it looks great, it offers little practical advantage and is more complex to make than a simple Philips style side pull. This is what all the Chinese makes use, including FP. These WERE used on lower end Raleigh held brands like Philips and numerous continental bikes.
Tubing, generally speaking is tubing, but there are some key differences in the frame designs. Older Raleigh's often had chainstays which are bolted at the bottom. All Chinese roadsters have riveted chainstays. This is not any stronger than the bolted chainstays...just easier to assemble.
The lugs are also different. Over the course of years, Raleigh use a number of different lugs on their roadsters (my observation). Some were quite sophisticated with multiple points. Others were simple with no scalloping on the inward side. The FP uses only 2 types of lugs…both rather simple.
In conclusion, while FP parts might interchange with a Raleigh, they might also interchange with any other number of roadsters: Gazelle, Umber, Bianchi etc….but it is not a copy of any of them.