I hear what your saying Goose.
I have supplemented road cycling with my football (soccer) for years (intervals on the road bike (stomps) did more for my endurance than running tempo’s ever did).
Cycling hits the hip flexors in a big way, especially using clipless pedals & ‘pulling back’ on the pedal stroke, hence what you said, ‘Cycling (bicycles) may improve (very slightly) the speed of your first step’.
Right…
But if your first step is quicker, second step is quicker then why can’t the extra leg speed in the first 2 steps pour over into steps 13 14 etc???.. You have generated the speed in the first 2 steps, surely if extra speed has been enhanced there, it carries over into steps 13 & 14 also?. Its there in the hip flexors, you’ve developed it, the CNS has remembered it.
If you have influenced the speed in the first 2 steps, surely that would influence power/speed throughout the race. Your banging out the same “greater” leg speed you produced in steps 1 & 2.