Broken Ribs

Has anyone tried turbo training or similar with broken ribs? I can't ride in traffic because the stop/start is excruciating but the pedalling bit seems OK... presumably I'm not going to cause any more damage if I keep my upper body still?

It's what the pro riders do when they've broken ribs, collar bones, etc.

Saying that, I've broken a fair few ribs in my time and I've ridden through it - raising the stem a good bit helps, takes the weight off the upper body.