This project is based on the Bobby Car for children, the result is a motorbike out of cardboard, some little helpers like wood, steel cable, a lot of glue and a looooot of patience :)

First to get all the steps: ergonomic sizes, functions and the outer appearance are the result of premodels. Then you could start to build in Rhino and PepaKura to produce all the pieces for the at least a fully working bike!

Enjoy the instructable!

Step 1: Idea / Inspiration / Technology

We are two design students and for finding our main idea of the kind of vehicle we decided to build a motorbike with two technical functions. After trying different laying positions we found to do the moving part by hand and the steering should work by foot. To get this kind of technology working, it's very important to hit the ground just with the neccessary parts. Here you see the biggest forces are from the front wheel and the back but front wheel from the Bobby Car. So it's turned around to keep the balance and to get the steering wheel more close to your feet.

Step 2: Premodel: Ergonomics and Steering Function

To find the ground shape of our basic construction and even the form for the ergonomic proportion, we built a crossed structure out of strong corrugated paper. From here on we could find the perfect form fitting to our bodies. Then we cutted out and off all the parts we don't need to fit in the Bobby Car and finding the best positions for feet and hands. (You need to know, we had a lot of premodells..) The idea for the steering functions appeared after a lot of other technical models, so finally this one you see is working and can be connected between feet and the Bobby Cars steering wheel. The function of the front wheel to us it as a crank handle wasn't neccessary to "premodel", it was working directly by just trying in original size.. puh!

Step 3: The Design

Now it's up to you to find your favorite Design :) Actually the best is building it directly at your 1:1 model and finding the points which you later can build in your 3D model. On this way we just measured the most important points and completed the model by putting triangles everywhere. Now you have your definite sizes and can start the real paper bike!

Step 4: Base Construction

In this step you see how to join the pieces to have your save main construction. For fixing the Bobby car we just put a little piece of wood through the three main layers to fix it with a big srew at its back stay. It's the only point, you remember, this part need to be hold back from hitting the ground.

Step 5: Front Crank Wheel and Moving Function

Here you see how the wheel is built up! We also used the big corrugated paper with some supports inside. The inner wheels are these which a rolling on the ground, the others are just for the look and to fix the handle. But all the paper pieces are fixed with the stick to get a big area to glue it onto. The little handle was fixed by a little piece of wood to be more safe the paper won't give in while using. When you have a closer look, we cuttet the end from the stick for a better fitting in the wooden layer. The white and thinner corrugated paper is the same we used for the body.

Step 6: Steering Function

The other and much more difficult technology, steering, needs to be strong enough not to give in while using your feet! So we removed the steering wheel of the Bobby Car to increase the angle to get a better turning result. To fix it we used steel cables. The pedals are out of many layes of corrugated paper but you need to be sure, that the hole for the axis is still big enough to move them easily. The two fix points at the pedal and the one side crossed steel cable brings the best moving balance, you also could just use one foot to steer.So there are always moving parallel in opposite directions.

Step 7: Build the Body

Now we are coming to the last step of builing the bike! After deciding how to split the body in Rhino intwo pieces (we made three) you finally can bring in into PepaKura. This program brings you the developed view which you can change however you like it to put together later. Then have a lot of fun cutting all the pieces, be careful not to mix them up! Then it's all about bringing them together and use the glue like I use the beer while writing the instructable ;) Just kidding.. To connect the pieaces we cutted a lot of little paper pieces to fix them from the inside that you won't see them from the outside. And just for remembering you again: The back wheel from the bike is just a mockup!