What’s required to convert a 2 speed Brompton to a 3 speed (adding a 17T) sprocket and a new shifter rather than going hub gear? Having tried @Arvy.’s 4 speed I’m contemplating an upgrade.
11 speed cassette and a thinner lockring plus the shifter conversion kit.
Buy the kit for both of the above from Minimods via bike gang
https://www.bikegang.co.uk/bikeganghut/Brompton-Stock-Integrated-2-speed-thumb-shifter-to-3-speed-indexed-mod-kit-MiniMODs-p431344504
https://www.bikegang.co.uk/single-post/2-speed-to-3-speed-external-cogs-upgrade-in-detail-minimods-x3-unibody-cog-set-or-x2-1
Plus you'll need a 9sp chain
@Mikey5000 started
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What’s required to convert a 2 speed Brompton to a 3 speed (adding a 17T) sprocket and a new shifter rather than going hub gear? Having tried @Arvy.’s 4 speed I’m contemplating an upgrade.