I ride 48*19 66 inches but i'm quite small and light. There's a couple of hills in the Chilterns I struggle on, Hale Lane and Kingston Blount. I regularly ride either Bison Hill, Ivanghoe Beacon or the Dunstable Downs on one of my regular Saturday morning rides.
The Hemel Hempstead Hilly time trial used to go up Bison Hill twice, it was one of my favourite events of the season.
I trained on fixed in my racing days over 20 years ago and bought the Pearson Touche mainly as a commuter but 18 months later it is still my sole bike. Currently looking at getting a Thorn Sherpa for a 6 month tour that I'm about to start planning either late June or July this year, riding the Manali to Leh highway then Thailand, Laos and Vietnam.