use the medium-sized ottolock which coils up to fit in a rear jersey pocket (or can loop under the saddle rails…but that takes extra time to deploy and hang back up). able to install/undo in about 30 seconds. good enough to prevent opportunistic theft/snatch and go but wouldn’t feel comfy using it and having the bike out of my sight for longer than a quick, two minute bathroom break or taco shop lunch order.