Btukfyl

Red/amber lights in the rear of the vehicle, white lights, in front of it: that is the good old convention and certainly switching their places is a bad idea.

A quick search, however, shows other colors available to purchase. Concerning "to be seen" bicycle lights, should they be avoided?

More specifically, I would like to have one blue light in the front of my bicycle (just because I find it more pleasing), but am I asking for trouble if I replace my white light for the blue light? Would it be a better option to use both?

A quick search, however, shows other colors available to purchase. Concerning "to be seen" bicycle lights, should they be avoided?

Yes, they should be avoided.

First, off-colors might not be legal in your area.

Second, and more importantly, no one will know what it is. If a driver sees a flashing red taillight, or what looks like a normal white headlight, that driver is likely to identify you and your bicycle. Something like a blue light is likely to evoke a, "Huh? What's that?" Which means most drivers won't treat you like a known entity - something they need to avoid.

And what do drivers (and cyclists, for that matter) do about things that don't evoke a familiar "must avoid" response? You won't even register as being there. Think about it - how many random items to you ride past all the time? Do any of them really register at all? Trees, mailboxes, plants, fence posts - they don't meet your brain's "must avoid" pattern, so you don't react to them at all.

You do not want to be cycling in the dark where you need lights so you're seen and safe, and then do any thing that makes it harder for others to identify you as a bicyclist.

Most places will legally require you to run with white lights on the front and red lights behind. This is crucially important because it immediately tells everybody else on the road whether you're coming towards them or moving away.

I once nearly hit somebody because they had a red light on the front of their bike. I saw that at the usual distance and dismissed it as a low priority, expecting it to be tens of seconds before I reached them and needed to deal with it. Then suddenly they were on me because we were coming towards each other and closing at 40+km/h, rather than moving in the same direction and closing at 5km/h.

Do not use random other colours because you think they look prettier. Vehicle lighting serves a critical safety function. It's not about looking pretty. If you just have a blue light on the front of your bike, that does not say "Everybody pay attention: I am coming towards you!" It just says "I'm probably not very important so deal with the other stuff and come back to me if you have time later to figure out what I am." Blue has the additional disadvantage that human eyes are much less sensitive to blue light than other colours. Blue, especially flashing blue, is reserved for the use of the emergency services in some jurisdictions.

If you want to put additional lights on your bike, standard colours are still better. Use a solid white and a flashing white (or two solids) on the front; ditto with red on the rear. Or put extra lights on your helmet or somewhere on your body. The standard colours convey important information; other colours are just decoration and people don't pay attention to decoration.

As long as you have primary rear red and front white, you can probably add in some other smaller lights of different colors - as long as your local laws allow it.

I’ve seen riders running rear lights with blue or orange in addition to red on my local trails.

I’ve also seen secondary orange front lights.