Buy second-hand bike in or near Frankfurt
I actually grew up near Bad Homburg, and have bought a used bike there. (You do realize that depending on where in Frankfurt you want to go, the way there from Bad Homburg can be quite far?) The two biggest bike shops there are Fahrrad Denfeld and Fahrrad Diehl. At least some years ago, both of these shops sold used bikes as well, and for reasonable prices. I think I bought one from Fahrrad Diehl for 150€ that I used during my 5 years of studying

Communicating in English should not be a problem in either Bad Homburg or Frankfurt, especially with people from "younger" generations / who are &lt; 50 years old