mattscq

I have a standard 2s Brompton from 2018 (I think?) but the gearing should be 54T x 12/16. It's been fine but I think I'd like to make it a little speedier. Generally what are the pro/cons of switching out the chainring vs replacing both cogs? I think the ratio between the two is about right but I just want a slightly faster gear than 12 and 16.

Schwinnsta

12 is the smallest so you have to go up on chainring. I have heard that 60 is the largest.

Jipe

There are third party cogs with 11t for the Brompton.

There is also a 3 speed conversion with 11-14-17t https://www.bikegang.co.uk/bikegangh...-9S-p194768178

2_i 

The problem is that you need to get again those special cogs every time you replace the chain. An issue with chainrings, when going with non-Brompton, is the potential lack of a chainguard.

Winfried

You could turn that 2s into a 6s with a BSR/BWR three-speed gear hub.

Hub Gear Calculator

iFold

the question is how fast would you want it to be, 20mph, 25, 30? In your current setup (54x12t) at 90rpm, you can go as fast as 20mph already. If you replace your 54t with 60t, you could hit the 25mph mark.