Why add a 60T chainring to your Brompton? Well, for one it will force you to pedal hard and faster and for two it looks incredible. Definitely the best way to make your Brompton into a racing machine.
The Brompton Crank uses a 130 BCD and that works perfectly with this chainring. You can even reuse your original bolts. However please note that you will need to purchase a longer chain. Any 3/32 bicycle chain that's meant for a road or mountain bike will do, and then you can just cut it to length.
We offer this conversion in the store, in case you aren't quite ready to start measuring and cutting bicycle chain to size.