I think you should add a button so you could easily look back without changing the camera angle.
perfect to use especially when climbing uphill.
Out of curiosity, why do you want to be able to look backwards quickly?
During a race, to know who is behind you, probably
The names + distance behind (bottom of screen) and the rider list with time behind + w/kg (right side of screen) aren’t adequate? I find myself thinking that if you’re at your limit, effectively racing the rider(s) behind you (what other time would you need to look right behind you?), then reaching out to hit a button (to look back) is going to break your concentration/rhythm more than you would want (?)… but maybe I’m wrong about it 
The names and distance behind of riders closing on you show on the bottom of the screen
You’ll see the distance count down
There’s another game which has this feature. I recommend checking out some of Jonathan Crain’s videos: he does really good work.