what's the transparent shield-like thing i see out front on some riders?

I notice from time to time a rider going by with a transparent shield-like fairing thing in front of their bikes…what is this?   I thought it might be a draft indicator, but it never shows on my bike???  any one know what it is?

I think they are in ‘Training mode’ - you can draft them but they cant draft you

That is correct. If you look closely you see their wattage on their screen. Also the color of the screen (blue, green, red, orange) indicates how hard they ride i.e. interval, recovery, etc. Those in a workout don’t draft and their trainer does not vary resistance with the terrain. But you can follow them and draft behind them.

Full document about workout mode can be found here: