It's absolutely ridiculous that there is no bicycling mode but it has it as a Move IQ event? This makes no sense. A lot us like to bicycle for fitness and if we choose cardio it doesn't track distance whereaswhereas other does. With the higher speeds of cycling, it needs its own mode.
There is a bicycling activity, but you have to add it in activity settings. Also make sure you are running firmware 4.0 or higher. When I first updated to 4.0 it didn't show up on device till I had done something, I can't remember if that was syncing with express on computer. I have been told that it reboots when connecting to charger, so that might also do the trick.
is this still the case? the manual that came with my new vivosmart lists bike activity in the activity list - but when I got to the app on my phone to select it is not shown as an activity option. if the watch doesn't have the functionality why include it in the manual?
It has the functionality since version 4.0. Check on device settings-info-software. Since the device only have 4 activity type besides walk and run (which are fixed) you have manage which one you want in Garmin connect settings for the device and make sure bicycle is one of them.