I don't really know what they could do to make the challenges better tbh, but I would love to see something other than a milage munching challenge. Maybe a elevation challenge which you must complete the elevation gain within a max number of miles. So you are forced to choose quality miles over quantity. Or something based on HR, a suffer challenge, only a certain number of miles below a certain suffer score count, after that only miles at or above the suffer score count for example (although problematic here because it is a premium feature and not everyone has a HR monitor so limits the challenge's demographic, but they could give this for free during the challenge, might encourage some people to pay up after having had a demo of the feature).