Crossing the Canadian border with all your camping/mountaineering/mountain biking gear?

Normally one to should have no issue. If your car is filled to the brim with content they may ask you to subject to an inspection. Looking for drugs, weapons, etc. So long as you don't have any weapons you'll be ok. You will be asked questions about where you're going, how long you're going to be here, the usual. Canada gets a lot of a people coming for "sports tourism", camping, etc. I assume you're American and with an American passport you should have no real issue entering. The worst is they'll ask you to fill out an entry form and provide you with a visitor report with a date you must leave by (usually indicated based on when you said you're planning to leave).