If you do want to ride, many shops do decent XC/AM rentals. I have no personal experience of renting from them, but I think your best bet would be Different Bikes in North Van. Best to phone ahead though, because it is off-season and who knows what that the current situation is.
http://www.differentbikes.ca/products/rentals
They located at Parkgate Village, base of Seymour mountain. Use Translink[/url] for bus schedules, I think the 211 bus goes downtown Vancouver to Parkgate in about 40mins.
From the shop, you’re about a 2min road ride from the base of the mountain trails. Buy a map at the shop. If you’re used to typical UK XC/trail centre riding then do an out & back again loop along the Bridle Path. If you want something steeper and more typically North Shore, go up Old Buck (steep) > Baden Powell (go west) and then descend on Pangor or Severed D. Give yourself 2hrs for these, maybe 3hr daylight to be safe as only some of the routes are obviously marked.