You are very correct. Without a feedback loop to Garmin that is reliable, riding on SYSTM alone is not a great idea. There is supposed to be a way to get the Garmin device to ingest SYSTM workouts but I’ve never been able to get it to work.
If you want to avail yourself of those 520 features, you will need to have it pick up power and HR. It’s ANT+ only so if your Wattbike and HRM broadcast ANT+ you can have the 520 pick that up and record the ride as it would an outdoor ride. It will upload to GC in addition to the upload from SYSTM, so you’ll see the workout twice in GC unless you turn off uploads from one or the other. You can also delete the duplicate if you want, but if it’s still on your 520, it’ll upload again until you delete it there too.
My Garmin Connect also gets SYSTM workout syncs and pulls them into the fitness analysis tool on my watch. The exception is RGT. I have to dual record those rides.
As you’re using an Edge not a watch (the analysis is done on the device) you need to switch on your 520 and sync it to Garmin Connect on your phone after the workout has uploaded to Garmin Connect. Leave it to do it’s thing then sync again.
thanks for all the answers, systm sync’ rides with garmin connect ok, but to get the full functionality from the gramin health and fitness features I’ll start recordings the sessions directly on the garmin 830.
Sounds like you just upgraded to a 830. Nice! It does slightly complicate things as the 830 also does BTLE for senors.
ANT+ sensors “broadcast” data and any number of recording devices can pick up that data. BTLE sensors require two-way pairing with recording devices and usually only have one channel, so only one device can record the data. Quite a few sensors and trainers are capable of doing both. So, with a trainer, you might use the BT channel to communicate with SYSTM and use ANT+ to record the data on your 830. When pairing a device that does both BT and ANT+ with the 830, there will be two sensors shown on the 830, one for ANT+ and one for BT. In the case where you’re using BT with SYSTM to control the trainer, select the trainer as an ANT+ power meter on the 830.