Cup-N-cones have provided a gazillion miles of trouble free bicycling for squillions of cyclists.The trick with those on the Bromptun is to re-grease them properly when the bike is new. Grease seems to be charged for by the inch at the Brompton factory.

The bottom bracket is sealed though, should you feel a need for new-fangled apostasy.

I should add, that you might try to hire or borrow one for a day. I hated mine utterly, but 500,000 Londoners cannot be wrong.