Dude, I'm sure you were and hopefully still are a great and well trained cyclist, but it is very unlikely you averaged 50.
Rohan Dennis, Tour de France record holder for fastest stage in the Grand Tour, managed to break the previous UCI one hour record in an inside hall, on a flat plane and achieved 52.491 km:
https://www.theguardian.com/sport/2015/feb/09/rohan-dennis-sets-new-hour-record
If your average was 50, meaning you sometimes surpassed that, you should probably get back on that bike and claim the record.