Wide open if the second image is to go by George. The isolation works well in that one and it is a nice image. Might be worth losing the red running out of the left hand side perhaps.
I wonder if there is a right way George because our view as photographers is often different than the competitors or organisers?
For the first two examples here both FL and f/4 have worked well. The important thing in the first shot is that the 'group' are all in focus if that is what you wanted.
I find the longer FLs give me more time to be able to vary aperture so I can hone in tight or looser on the subject to get a selection. For my last two races I have used the 70-200 for the vast majority of shots after the start where I rely on the 28-75.
That's something we never get here although this year for the first time a police motorcyclist escorted (from behind) a disabled low trike rider whilst it was dark.
I'd say your settings worked well. Nice job.