We ride a tandem and were recently in training for the "London Nightride" charity 100k.... so during the lead in to that we had been "getting serious" about lighting (just before the ride I counted how many switches we had to operate and it was about 12 - counting bulbs I think we reached over 21!)....

In terms of advocating to cater for redundancy let me just say that come the ride due to multiple issues it came down that we ran with one tail light on the bike an done on the helmet. I have to say I feel most comfortable with triple redundancy rather than double now, depending I guess on the context (this was a group ride with stewards in places, urban environment, so actually safety arguably not such an issue).

One of the things that adds a lot to our lighting setup is a "pedalite" on the rear crank. These were a birthday present to my stoker and it must be said they do weigh a fair amount, so would not suit everyone. Also the pedals are clunky and create a certain "pimp my ride" effect, again not to everyone's taste.... But I believe in terms of a safety lighting addition to be seen these really hit a sweet spot, also in terms of value for money.

I am still aspiring towards a dyno hub as my primary lighting solution, but this will always be supplemented by one or two battery backups - perhaps one as supplemental and another as "emergency" (to cover a failure).... I have been told the latest dyno hub led technology combined with the capacitance built in makes for a very viable solution - just I need to save the money and have other priorities ATM so it is a year or more down the line in the future...