The stats for collisions from rear are surprising, rarest way to get hit on a bike (and most of those are no lights at night).

It turns out, moving closer to the center of the lane reduces the chances of the most likely directions of impact - namely turning traffic. Either turning left as an oncoming vehicle, turning out from a side road or driveway, of someone that is overtaking you and then turns right.

I've found low speed crashes really want a helmet. Things like you roll sideways off the bike. You are not moving fast but are rotating quickly. (So back hits ground followed by back of head)

FWIW, I just noticed the common irrational rational fear of being run over from behind. It is a common mistake. Riding to the extreme right can make it worse, it is an invitation to pass when instead the cyclist is just afraid. Taking a little more room on a road (situationally) can make a person a lot safer.