How to mount posters, bills or placards on a bicycle We want to do a ride through our city to show the presence of cycling and want that people do not only see bikes, but also a message.

We thought of using some posters that we mount on our bikes, but we are not sure how to do this. We thought about glueing the posters on card board and maybe even reinforcing the card board with wood. We are thinking about A3 sized posters, or even larger. If there was somebody with experience on how to build posters so one can mount them easily on a bicycle, tips would be appreciated.

Other tips on how to convey a message as a group on bicycles would also be nice!

I wanted to keep the problem pretty open, so it can be of use to other people facing a similar problem, but since they have been requested:

Specifics are as follows: We want to make a bike ride in suits to show that cycling is possible in any attire, and I opted in to find a solution how to make posters so people see our message and do not just wonder about a group of cyclists in suits. We might need a big poster in front and in the back, and the individual cyclist should also be able to mount a message on their bikes easily (want to make around 5 smaller posters). There should be some trailers available.

It would be nice if the posters are reuseable, maybe even for different purposes, but the ride I want to use them for will only last around 2 to 3 hours.

Budget is pretty tight, I would guess around 50 $.
The most practical approach we found for larger posters was trailers. Like this They're somewhat inclined to fall over in the wind so you have to be a little cautious, but the group who were using them lent them out to a range of people without any problems (other than getting the trailers back afterwards). You can attach the same A frames to a loadbike if you have one. 

Up to about A3 you can strap to your back, ideally to a backpack, or to the sides of a rear rack. I've either laminated posters or printed on coreflute, then stapled them to a wooden frame and cable tied them to the bike. The problem is that you have to print large for people to be able to read it, and that means "BIKES GOOD" rather than a paragraph. The graphic below I stole from a guy in Sydney because it's IMO good - simple, easy to grasp and direct. You could leave the "critical mass" off if you wanted to, obviously.



If you want to attach slogans to cyclists it's easier to do it on a T shirt. Critical Mass have a huge range of advocacy shirt designs and places like the Chicago Flyer Exchange have a range of artwork ready for you to use. People will generally pay you for the shirts, so you can use them to fundraise a little as well (cost of a printed shirt is usually a lot less than people expect, so just rounding up to the nearest convenient price usually results in a cheap shirt and a small surplus).