[logfromblammo]

That isn't the only thing wrong. If you brace the back wheel, the fore tube still has a single point of attachment, and the front wheel would tend to flex forward, encouraging the weld between the rising forward diagonal of the triangle and the fore tube to break.

It might not break right when someone sat on it, but after stresses accumulate from riding over bumps, the front portion is going to break off and pitch the rider forward into the pavement.