Literally EVERY German has a bike with a bell attached for convenience when passing. If a biker comes up behind you and sees that you are going to be in his way, he dings his bell. You move to the right, no questions asked. Don't look back, you never know how much time you have. Some dingers ding early, giving you ample time, other dingers ding at the last possible second, almost running you over.
It was amazing how quickly the dogs have learned not to look back at the sound of the ding, only move over to the right.
My friend Kathleen, however, was a different story. First time she heard the ding, she slowly looked back AND moved left! HUGE mistake that could've cost her her life, or at least a bad fall. Luckily the German did not hit her, only cursed, frowned, and acted grumpy, you know, the usual German interaction.
So remember, if you hear a 'ding' while in Germany, MOVE RIGHT.