Re: Crushed nut algorithm
According to Richard's Bicycle Book ( late nineties edition), the only purpose of fixed-wheel bikes was for training - forcing the rider to spin quickly when going down hill and pedal powerfully when going up can help tone their legs.
If I lived in a mostly flat area, I might not bother with gears (one less mechanism to maintain, and a single-speed bike can have thicker, more durable chains and sprockets), but free-wheel hubs are so reliable that there is no practical reason not to fit one.
Each to their own. My personal preference for a flat city would be a BMX (if chained to a fence those small tough wheels present a challenge to any pisshead who wishes to kick them in), but I would respect the choice of anyone riding a cyclocross bike, hybrid, folding Brompton, mountain bike, whatever if it works for them.