None.

Unless you want to get beaten to death.

This also goes for bumper stickers.

Nobody will get convinced by these stickers.

But you're likely to get killed by a psychopath and lose a vote, since dead people cant vote.

Also the psycopath could get away with it, and they still get to vote.

Not worth it.

None because I wish to get to my destination unscathed. It’s dangerous enough riding a bike on a road especially in an area that is openly hostile to bikes. They’re considered a “lefty thing” here. Suggestive political stickers will invite outwards aggression from over 50% of drivers. Not worth it.

Stickers with solvent-based adhesives can adversely affect the plastic in your helmet, shortening its life.

That's the line you get with hard hats and motorcycle helmets at least. To me, I think stickers make it easier to miss signs of damage. I don't slap them on my helmets of any sort and I replace my helmets after noticing any signs of damage.

Stickers go on my water bottles and most of them are John Carpenter movie references.

I ve seen a popular one saying burn fat not oil but while on one hand it looks cool/edgy, on the other hand you pass for one of the douchy bumper stickers guy.

Just get an extra high visibility sticker and one backup light on your helmet

If you are into folk punk then you should check into stickers from this great band!

Anything non-aggressive, like "78c out of 1$ gas money is taxes"

I don’t hate cars, people, and what they do, I hate their ideology. I don’t tell them what’s right and what’s wrong, I explain to them what problems I see, and nothing else. I‘m driving an old okayish car I’ve fixed countless times myself, the car, with all costs, is cheaper than any flat within 30 minutes of biking to work.

Basically anything Spike says, but unironically

"3 feet over or 6 feet under"