Sanwa is a bicycle brand that was owned by Wisconsin Cycle Supply starting in 1977. From what I have seen these were all road bikes imported from Japan. Wisconsin Cycle was a distributor from Sheboygan, Wisconsin that distributed bikes, another brand they used was Timberlin. Riteway would buy Wisconsin Cycle Supply in the 80s and I believe that is when the brand disappeared. Riteway was later bought by GT.
Sanwa was also the name of a manufacturer in Japan, possibly the company that was used to manufacture the bikes for Wisconsin Cycle. I’ve seen a lot of people connect Sanwa, Sekine, and Yamaguchi. I believe Yamaguchi merged with Sekine who then later merged with Sanwa. The Sanwa factory closed in 1997.
Sanwa bikes were sold in bike shops, and I believe by Montgomery Wards.
Here is a really nice 1980s Sanwa 700 road bike:
The frame uses Tange Champion #2 tubing. Components are Suntour ARx, Sugino GT crank, Dia-Compe brakes, Araya rims, and Sanshin hubs.
110 road bike
210 road bike
212 road bike
250 road bike – mid-level road bike with Suntour AR derailleurs and Sugino GT crank.
312 road bike
400 road bike
700 road bike