Originally Posted by
steelbikeguy
However... one universal rule is "everything can break", so I also carry a small spare headlight in case I have a dynamo wire break or the headlight goes belly up. Side note: I make my own headlight and taillight, so I'm aware of the potential for human errors causing malfunctions.
I chuckled a bit as this is what you'd need to cover all the things that could break...
Dynamo lights - in my experience - are as reliable as the other things I don't worry about like frames, crank arms, shifters...