This shifter conversion part will convert the post-2017 Brompton integrated derailleur shifter from 2 to 3 speed. The new shifter is indexed, and include a stronger lever spring that will eliminate many of the "sticky lever" issues commonly encountered with stock derailleur shifters. The conversion is easy to install and completely reversible.
Due to popular demand, we are making the shifter conversion parts available by themselves, separately from the complete 3 speed kit. However, please understand the following notes before deciding to try.
Shifting performance depends on multiple factors, where precise cable pull is a/an (important) part. Other factors such as cog spacing, whether shifting ramps on the cogs are matched, and the type and width of the chain are also important. When any such factors are mis-matched or missing, shifting performance will deteriorate.
The shifter conversion parts are designed to match road bike 11 speed cassette spacing. In other words, the distance between the cogs need to be 2.1mm. The shifter are compatible with 11 and 12 speed chain, with 12 speed chain being more tolerant.
The conversion will result in a shorter but firmer stroke, accompanied by an audible click. The stroke for down shifting (to larger cog, or "-") is approximately half of what it used to be. When pushing the lever all the way down in one stroke, two gears are changed, such that the chain will move to the largest cog. This functionality is similar to many road bike/mountain bike shifters.
The convert parts included a stronger lever spring, which is also available separately. Here
Should you have any other questions, please feel free to contact us.