Ride with the flow of traffic.

Setting aside all of the other variables, let's assume that a cyclist is riding with the flow of traffic at a speed of 10 mph when they are hit from behind by a car travelling at a speed of 35 mph, that means the cyclist is really hit at 25 mph at the time of impact (35 - 10). Now, if that cyclist were to ride against traffic, and using the same speeds for both cyclist and car, then the cumulative speed at impact is 45 mph... which one do you think has the greater odds of surviving?