and now I have a lumpy bruise about 2" in diameter a few inches below my collarbone and a bit to the right of my sternum (I was only going about 10mph). Is it safe for me to do my benchpress, or should I wait a few days? I’ve been treating it with cold compresses.
It aches a little teeny bit to move my arm around, especially if I move my arm forward from my body and toward my center mass.
i’d be concerned that you might have brused your lungs or heart in the accident. it would also be possible for air to be escaping into your chest cavity, or for blood to be collecting in the sac around your heart. those are the worst case type stuff. scary thing is 10mph is fast enough to do it. i’d recommend seeing a doctor
Could be trivial, could be serious. Either way I wouldn’t be pumping any iron until I’d seen a doctor, and soon. I wouldn’t be relying on on-line diagnoses from well-meaning amateurs, that’s for sure.
I have no advice to offer on your medical condition, but as a American Motorcyclist Association Field Rep, I’d like to remind you that bruises like that are the reason dirt bikers wear armored breast plates. Wear your gear next time!
Get well soon 
Hmm, it’s been 48 hours and I haven’t died yet. I’d go to the doc but I have no insurance, therefore I don’t go unless I am in serious pain or bleeding or something. I have none of the above*.
Dorjän, you are of course, absolutely right, and I shoulda been wearing armor. In my defense, I was only tooling down the road, but now I see the light, oh yes. 