Brompton chainsets (cranksets), chainrings, guards and cranks

Replacement / upgrade Brompton bicycle chainsets / chainwheel guards and crank arms

The chainset (or crankset in US terminology) refers to the components of the bicycle which with the pedals drive the bike forwards

The Brompton chainset does not include the bottom bracket - that is supplier separately

Early Brompton bicycles used a fixed chainset where the crank arms were permanently attached to the chainring - so if you wanted to upgrade / change gearing - the whole component required changing. Very early models had a 40T chainring

In 2013 a new spider crankset was introduced - this allowed the chain ring to be changed if it was worn or if a gearing change was required

In 2015 the new spider crankset was made available as an upgrade to older bikes

In 2016 the older fixed crankset was discontinued

Brompton bikes now come with a choice of 3 chainring sizes: 44T, 50T and 54T (44T gives the lowest - easiest peddling - gearing, and 54T gives the highest - highest attainable speed - gearing)