I just completed the December Strava Challenge with 130 km on Saturday the 27th. The Strava monthly challenge is to ride 130 km in a single ride within 24 hours. The 130 km converts to 80.77 miles, a fair distance for a single ride. For me, riding up to 60 miles is fairly easy. Past 60 miles, on up to 80, is a bit tougher.
Strava had a different 130 km challenge each month in 2014 with a different colored jersey for each month. Once you complete the challenge you are eligible to buy the jersey, which was expensive at $120 per jersey. But the biggest benefit was doing the challenge and therefore staying in some sort of shape throughout the year. has as many detractors as fans. Many feel that cyclist striving for KOMs on various segments become marauding lunatics who who do not care about road or trail etiquette. Strava was sued by a cyclist's family who felt that Strava was responsible for his death.  Kim Flint was trying to regain a KOM on a downhill segment that he had recently lost in Northern California, braking to avoid a car and losing control of his bike in 2010. Others feel that cyclists become digital slaves to the app, cycling more for statistics and challenges and less for fun.
I use Strava for motivation. I still am courteous and helpful on the road. I often forget that the session is being recorded. As opposed to the obsessed Strava manic portrayed on YouTube.

These are the monthly Gran Fondo challenges that I achieved in 2014. At $100 to $120 a piece, I bought the jersey, merely to replace some old jerseys where the elastic has given out. For 2015, Strava jumped the price up to $145 per jersey. I don't think I'll get any this year. $120 plus shipping was about my limit.
May Gran Fondo Badge
June Gran Fondo Badge
July Gran Fondo Badge
September Gran Fondo Badge
October Gran Fondo Badge
November Gran Fondo Badge
December Gran Fondo Badge