So I fixed my bike this week
Gone from a triple chainring / 8 speed setup, to 1 gear 16/36.
Don't have a rear brake on it - due to not being able to fit a standard dual pivot on my frame (unless they can be secured with a M5 bolt and fit over a 50mm mudguard!).
Has a dynohub, mirrycle mirror and an airzound for commuting.
Used the sheldon brown method of filing the axle slightly to give me some movement to tighten the chain, also used a "near magic gear".