As an American club rider in the late 1970s, I asked the same question. Where was the West German equivalent to Raleigh, Peugeot, Motobecane, Gitane, Puch, ALAN, Colnago, Panasonic, Fuji, Paramount?
There are different types of questions mixed up here, starting with the OP and carrying through to responses. We’ve established that there is German cycling tradition, that there are German high-end brands and manufacturing, and that there are strongly German bike styles. The question you’re raising is something different, and I think largely has to do with the war, the division of Germany, and its post-war industrial development.
The war itself was crippling to companies; most industrial activity was deployed for the war effort, of course, but the loss of equipment and livelihoods meant some bike companies ceased during the war and never restarted. Many of the pre-war bike brands, like NSU, Wanderer, Express, and Steyr, were in what become Soviet controlled East Germany, and shut off from the western, capitalist inputs which drove the development of other EU and American brands. Germany’s economic recovery was not really in effect until the Wirtschaftwunder period of the 1960s, at which time those bike companies which did restart did so working in a country half the size it was, and were effectively decades behind other countries’ bike industries. The Marshall Plan was designed to rebuild European and West German industry, but there was not unfettered growth and some industries were not supported, or were restricted, and key supply industries were, in some cases, on the other side of the Iron Curtain creating crippling shortages.
In short, the WW2 was devastating, and the post-war development meant it was almost impossible for the German bike business to grow in the same way it did in the USA or other parts of Europe.