Brompton wheels & drivetrain specialist

4 Speed shifter Conversion Kit for P/T shifter (11s sprocket application)

The Brompton P/T line shifter (a.k.a Brompton Advanced Shifter) is 4 speed from the factory, for use with Brompton rear derailleur and (road/MTB) 9 speed sprockets. When increasing the number of gears, physical space is usually a constraint, and thinner 11 speed sprockets and spacers are typically used. Due to the difference in sprocket and spacer thicknesses, the P/T shifter cannot be used, as is, on those applications.

However, with this revised shifter internal, the P/T shifter can now be used on external 4 sprocket applications*, using the classic style chain pusher, Brompton factory derailleurs, or the 3^rd party derailleurs**. Examples of applications are:

- C line 6 to 12 speed (4x3) conversion, using either 3^rd party rear derailleur or classic chain pusher,
- C line 2 to 4 speed conversion
- P/T line 12 speed, using older 3 speed hubs, e.g., (BSR/BWR)
 
*If using your own sprockets, please make sure the sprockets and spacers conform to the (road/MTB) 11 speed specification, i.e., the sprockets are 1.65mm in thickness, and the spacers are 2.1~2.2mm in thickness. When stacking 11T and 13T sprockets, particularly those sprockets from road cassettes, do check that the spacing is correct. Some will actually have wider spacing than normal, and may cause shifting issues.

**3^rd party derailleurs must have the same cable pulls as the Brompton factory derailleur (as equipped on the P/T line bikes). While most Brompton style single pulley derailleurs are compatible, a notable exception is the Thx4ride proprietary derailleur.

Kit content: