It may seem obvious to somebody who has been hauling for awhile, but bike trailers work in a couple of different ways – either by physically clamping to the frame of your bike or by using a special attachment point that gets installed on a new wheel axle.
A big determining factor is what types of brakes you use, but most modern manufacturers have accommodated for the increased popularity of disc brakes and manufactured universal clamping systems.
Any decent trailer system will have a fail safe strap that also loops around the frame of your bike in case the primary clamp fails.
This is very similar to chains on the trailer hitch for a truck — it provides a backup.
The joint that meets the frame is flexible, so that it bends while you corner and maneuver.
Although my first bike trailer didn’t have this feature, almost all newer bike trailers are flexible enough to allow the bike to actually fall all the way over without tipping the trailer itself.
This is very important if you’ve got your kids in the back and for some reason, you fall over with the bike.
Unless you’ve built or modified your own bicycle trailer, newer trailers fold down for easy storage and are usually made of lightweight aluminum or steel frames and covered with weather resistant synthetic material.