I’ve gotten icy to 3rd degree receptions all four times entering Canada. Three of those times were by bike. Only once was the American border agent surly upon reentry. The agent at Del Bonito, MT didn’t even ask for ID. Simply asked if we were citizens and how long we had been in Canada. (Two days.) That was before 9/11, however. And we were on an ACA route, so I’m sure the guy was used to seeing cyclists.