Rings can be replaced in less than a minute with only a 4mm allen key, without removing your crank. Simply loosen the bolts 2 turns, unlock the ring by rotating it by 20 degrees and pull it over and off your crank. Reverse these steps to install your new ring. If you plan to ride a trail that you know is steeper than your local trails, you can switch to a smaller ring in the parking lot, in less time than it takes your friend to put on his riding shoes!