Doppio CX & Doppio BX

The Doppio Bottom Bracket Drive System by Kappstein is a milestone in the era of bottom bracket drive systems for bicycles. By using high precision components and low tolerances, Kappstein succeeded in developing a solid and with little more than 1cm, one of the smallest planetary gear system on the market. Moreover Kappstein has been successful in providing a gearbox with two different types of shifting. Depending on the version it is possible to switch between the two gears by using the shifter on the handlebar (Doppio CX) or by doing a short back-kick with the crank, the so called "kickshift" function (Doppio BX). The gear ratio for both versions is 1:1,57. Due to the compatibility with any 68/73mm BSA bottom bracket, many combinations
(fixed gear, wheel hub motors, rear shifting systems)
and therefore different fields of application are imaginable. Most planetary gears consist of 3 or 4 planets, the Kappstein planetary gear has 6 planets! As a result, the attrition is reduced and the durability extends.



weight comparison

Also the weight can pass after a comparison between comparable urban 2 speed groups. As the Doppio consists out of steel it maybe gives the first impression that your bike will get a bit heavier, but thats not true. Actually your bike could get a little bit lighter, because of the light parts around the bottom bracket and the very compact design of it.


Doppio SetShimano Metrea SetShimano Crank Set - 4 Square
1250 g1317 g1456 g





  • 2-Gear Bottom Bracket Drive System
  • gear ratio: 1 : 1,57
  • gearshift: wire or "kick-shift"
  • chain line: 43,5mm
  • Q-Factor: 185mm
  • 32T standard chairing
  • bowden cable holder with innovative clamping mechanism
  • compatible with all BSA Bottom Brackets
  • 6 planets (extrem precise CNC-machined)
  • tech. service: after 5000km or 2 Years
  • application field: city, urban, eBikes, trekking
  • JIS square
  • 4 x 104mm bolt circle
  • currently only available for OEM's





in cooperation with:


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