The side panels are held up mainy by the handle bars. The coroplast is cut out so the handle bars are able to fit inside it. Duct tape always helps too (Not to mention zip ties).
The panels move and flex with the steering, and are quite stable hanging on to the handle bars.
Notice that the roof is extended using cardboard. This was a test, both to stop the heavy rain, and beating sun.
Also notice that the roof, has a flap that opens to blast some air in... it works! I plan to make a coroplast roof soon.