Doing this next month from Knighton but we are puzzling how to get back to starting point. There are only two of us so taking two cars would be a lot expensive. IMBA book recommends the train but then you have to change in Shrewsbury which seems a faff with loaded bikes in a busy station. Thought about train to Newtown and then riding the rest but that is still 20 milesish probably on the same day as we finish the actual ride [ we are taking the 4 day option ]. Taxis look expensive , and we don’t have the time to have a leisurely pedal back over a few days.
So, what did people find worked out best for them?

Park in Shrewsbury catch the train to Knighton, ride, aber to shrewsbury train, book your bike spaces thou, only two on the train.
http://www.heart-of-wales.co.uk/timetables.htm

Good plan! Hadn’t thought of that.Cheers!

Do book in advance though, I had one accommodating guard and one very arsey guard…

Alternatively, do it in three days and use the saving on accommodation to fund a taxi!