Originally Posted by
Walter S
Yeah, IMO a dyno is reliable enough that you don't need backup. I put a shymano hub dyno on my bike in October 2012 and I continue to use it problem-free nearly every day. I keep it turned on pretty-much 24x7 as I think enhanced visibility in shade/shadows might give me a wider berth on the road - anything to draw attention and wake up the day dreaming drivers.
We've ridden for years with Dynamo's (some hub, some bottle) and only one instance I can remember about 5 or so years ago when a wire came loose. They're always on the bikes and always ready whenever needed. I've never known anyone in Netherlands or elsewhere to carry a back-up.
OTOH, forgetting to charge batteries? Or forgetting to find and take a light?