I've been a subscriber for quite a while, but aside from supporting an app I really enjoy, don't really use any paid feature or enjoy any benefit from it. One that I liked the idea of is group challenges, but it seems so bodged by Strava that it is pointless.
Firstly quick and to the point, put it on the website. A lot of people don't use the app very often, why is the web platform missing so much basic functionality from the app??
Now the real request. Please make group challenges more useful by allowing non subscribers to participate. The 3 challenge limit is pointless and it's not going to encourage anyone to subscribe, it's just going to discourage subscribers from bothering to use this feature that they are paying for. Fair enough, don't let non subscribers create their challenges, but let them participate and engage with the platform. I don't create challenges because my friends would quickly be unable to use them anyways. Get people more engages by letting them to participate and they may feel like subscribing. Instead the features so limited it makes me question why I am subscribing aside from trying to support this app.