Is there a combined cycling and public transport option that works out for you?
My commute is about 14km each way, but occasionally if I'm on the heavy bike taking some equipment in (or just tired) I can do half of it on a train - I'll go into the city centre downhill then take a train out of the other side of the city to a couple of miles from work, since it's heading away from town it's never crowded. Takes about the same amount of time, sometimes longer, but if I take it easy I can get away with not needing a shower at the other end.
There used to be someone in our office that was a commuter from Skipton, about 30 miles away. One of the other guys that still works here remembers regularly passing him on the way to catch the train in Skipton and then seeing him already in the office when he got her.
I did a sixty miles commute home as a one-off a few years ago, Warrington to Leeds over the Pennines. Just about managed it in daylight.