Indoor Cycling

Strava do not have a matching set of Activity types with Apple.  
I do indoor rides with an Apple Watch but they become’rides’ in Strava but with a different bike. 

There’s a feature request that you can vote for:

Thanks BryanC! What activity exactly do you chose on iOS (iPhone)?

​@Guus16 It’s not an answer to your original question, but if you edit the the activity on the website instead of in the app you can set the indoor cycling tag for rides: 

Thanks!

I just chose ride, but there’s a better answer below that involves the web site.