[bena]

I didn't want to mention what I thought was wrong because I didn't want to accidentally influence anybody else, especially if I wound up wrong.

But yeah, after giving it a good, long look, along with his mention that it would break when someone sat on it, I guessed that there should have been a bar between the back wheel and where the pedals are.

[skykooler]

I'm not sure it would break when you sat on it; the chain would be in tension, holding those two sections together and filling the task of that bar. The problem would be when you started to pedal, and that bar is not there to stop the chain from pulling the rear wheel towards the pedals.

[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.