When you set up a production chain, the result is not realy specified. The endproduct is allways the Cargo “Goods”.
The town needs only the endproduct and everything is fine. To increase the grow of the city you need to cap this demand and provide a good setup of tram/bus system through out the city and a good conection to other cities (low frequency wins).
If you want to increase the production of the factories around your city you need to lower the frequency between the factorys and the city.