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

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.