Fixed the spelling 'Efno' reads like a quite negative opinion.. (Polish brand naming may need revision)

said to be 28 40 50 ish? all overdrive [1+ 43% , & + 79%] internal torque goes to the BB spindle?
[read Metro is a 28t + 1,6x '45't]

Not all Schlumpf installations require Chamfering the BB edge.. the Speed and High speed over drive do. its the friction grip that does the torque transfer

the greater torque of the Reduction gear Mountain drive , needs a solid torque arm. regular bikes its a coaster brake like strap around the chainstay.


Brompton version, the torque arm has a Knob, it sits on top of the part behind the BB where the rear pivot Is for the wheel Fold.

It was pretty plug and play.. Have the hook-spline wrench & a few pieces required ,
like : shuttle pin for the shift button has to be protected from a crank arm puller..

my Brompton BB shell edge was not flat faced , nor perfectly chamfered .. but it, some where in between, seems to be OK..


M3L .. front and rear planetary combo works well for the 4th to3rd double crank+ hub shift, ... to grab that lower range bogged down on a Hill..