If you aren't there to offer first aid, didn't witness the incident, aren't related to anyone involved, and don't own the property where the incident occurred, you have nothing to offer. Get out of the way and let the first responders and/or police do their work. If you want to advocate for cyclists, join an advocacy organization, call your elected officials, and write letters to editor, but don't get in the way of people trying to work.
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Formerly fastest rider in the grupetto, currently slowest guy in the peloton