The Schlumpf Innovations range of geared bottom
brackets-- made in Switzerland to
timepiece precision. Instead of running multiple chainrings up
the front with much overlap in the gears, a planetary gear system is employed to provide a unique gearing between the the crank arms and the chainring. This means
that with the Mountain Drive option,
for example, your chainring spins at 1:1 in direct drive and your cranks rotate 2.5 times for every single revolution in low range. Using a 60-tooth up
the front in direct drive,
it drops down to the equivalent of a 24-tooth in low!
See Schlumpf for more info and instructions.
Drive - high 1:1, low 2.5:1
Speed Drive - high 1:1.65, low 1:1
High Speed Drive - high 1:2.5, low 1:1
Available as an upgrade
on X-series and GTT trikes at time of