Question:
I borrowed an old used bike from a friend of mine to teach my sone how to ride a two-wheeler. The bike was crushed by a car (while on the ground). Is there a ribbis problem if I return a bike that I had in my garage if my bike is a more expensive than the one I borrowed?
Answer:
The prohibition of paying interest applies to loans and payments etc. There is no prohibition of paying interest when returning stolen money. It would seem to me that the responsibility that a borrower accepts for the borrowed item can, in this regard, be more comparable to the case of returning stolen money than the case of repaying a loan. As such there would be no prohibition of adding extra money, particularly so in this case (in which you are not giving back more money, but rather a similar object although is worth more).