How do I record distance on a spin bike?

I think your only option is using a speed sensor, but I don't know it it's possible to attach it properly to the bike.

Thanks tmk2
Good suggestion, and although Im the GM, Its a commercial club and I cant afford to mess around with the Bike Electronics that already exist.
However, I will take this suggestion to Life FItness and see what we can do in that regard. 
Brilliant!

I just edit the activity in Garmin Connect after syncing and add the distance.

It'd be easy to add ANT+ and BTLE protocols but gyms keep equipment for decades so things are slow to change. Look how much equipment at the gym still has old-style 30-pin iPhone connectors, dangling, useless. (or maybe I'm just going to *** gyms)

Maybe with the rise of smartwatches, it'll just be the norm for new equipment to have connectivity.

Thanks CJ. 
Much appreciated!!

Any updates? Look forward to this - bought a 2020 latest version, see distance in km and Speed, but this info is not being shared to my watch Garmin Fenix 6s...

If you use the xert app on your phone and upload it to xertonline and connect that with strava you have all data.

I use syncmytracks app to upload to garmin connect or polar flow. Als you can connect your ic7 bike with stava with the ICG app. But Xert is better.  

On Xert How do you get the speed, power reading etc? mineis always 0 even choosing every sensor. The IC7 seems to be very picky on broadcasting these readings