Turned 55 the other day. Despite firm resolutions to commute every day, it's been freezing and very wet and windy (by our standards anyway, you northern americans may disagree) so I've woosed out and taken the car ... something an ageing wombat is entitled to do.
Still riding and loving my Hillbrick and yes, custom built IS the way to go. The Europa's gained mudguards and fatter tyres and is now my wet weather bike. The geared bike still wears the muck and filth from her last ride, 12 months ago (nearly to the day) - I have plans to wash her and make a few changes, but can't for the life of me imagine what I'd use her for.
Still riding 70 gear inches (48x18). There's a 3km, steep hill on the route to work because I live in the hills and the city is on the plains. Going to work (or anywhere north) sees me belting down it at 55km/hr+ which is a cadence of over 160 - that's no longer scary and I'm loving it ... which probably says something about growing older and fading mental capacities. Climbing back up is still the hard bit as I'm reduced to about 10km/hr for most of that 3km which is a cadence of 30. Not good. The steepest bit hits 10% but fortunately, it's short and there are a couple of false flats where you can 'rest' - you're no faster but at least you can ease the pressure.
The rest of my riding is fun and fine. Regular trips from 30km to 80km - not enough time to do longer thanks to committments with kids (yes, at my age, I have a 10 yr old ... and her 19 year old brother).
Fixed gear - it's great. People try to justify it with all sorts of reasons, most of which are valid but to be honest, the ONLY reason I ride fixed is because I love it and that's the only reason you need to do anything.