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A person that knows about the race and riders, finding them to specifically give them food; clearly support and private assistance.
A random guy outside a shop that knows nothing about the racer or rider, who enquires what a fellow cyclists issue is. And without being asked, offers to give their own brake pads to said rider. Not support, but just lucky coincidence.
Hopefully you can see the difference.
Do not assist racers. That's support.
Just write a message on the road to all racers, or stand and cheers.
Giving racers food is support.