Check this links may be usefull for you

http://www.instructables.com/id/How-to-build-a-bike-trailer-1/

https://www.wikihow.com/Build-a-Bicycle-Cargo-Trailer

for me the children weight It should not be a problem if it is used to transport heavy things, which should not be done, otherwise it should be more robust construction.

Hello

I think first think size,then wooden material strength , then design as need of children.

Hello,

i guess from our experience, it is better to use bamboo wood coming in various diameters. the weight constraint is the driver weight mainly to multiply by a safety factor about 1.5 Or little more. the structure is strong and light. A trailer can also be designed with the same wood. You will need metallic joints.

best regards

Thank you for your answers.

Maximum loading capacity is 45kg

what still bothers me is the shape of chasis!

what should it look like? should I copy from car?

Copy the principles of a car chassis to suit your needs.

Try to have a low centre of mass and a wide wheel track to help stability.

Use strategic, short struts to add torsional stiffness instead of using much larger sizes of wood.

Using some type of suspension component will allow much lower stresses on the frame but may be practically impossible.

Thank you very much for your helpful information.

I decided to put a spring on each wheel.

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