Whenever I've done 'event' rides, I've usually kept to myself, ridden alone and not gotten into any drafting situations. I just prefer riding alone.
Well, except that one time. I rode a Century, and at about Mile 92, facing a stiff headwind, I latched onto the tail of some riders who were definitely younger and fitter than I was. I didn't ask and I didn't get into their rotation either. But I did say "Thanks!" when I finally let go.
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"Don't take life so serious-it ain't nohow permanent."
"Everybody's gotta be somewhere." - Eccles