The Schlumpf Drive is a unique, 2 speed cable-free crankset. This allows you to ditch the front derailleur and shift between gears with any part of your body that can reach the shift button. They can be installed on nearly any bike, trike, tandem or hand cycle and work with internally geared hubs and derailleurs. Because the Schlumpf Drive is shifted with a tap of your heel on a foot powered cycle or palm of your hand on a hand cycle, this opens up the door for many riders who may have trouble with traditional shifting methods.
There are three major categories of Schlumpf Drives:
Mountain Drive – 2.5x gear reduction. Whatever chainring you have is reduced by 2.5 times when you engage the reduction. This is a great option for cargo bikes, handcycles or any bike in need of some seriously low hill climbing gears. If you had a 50 tooth chainring, the Mountain drive would allow you to pedal with an effective low gear of 20! The range is wide enough that you’ll double your gear range with almost no gear duplication.
Speed Drive – 1.65x gear magnification. This version gives you a slightly wider gear range than a traditional road double crankset. With a 30 tooth chainring, you will have the equivalent of a 30/50 crankset but never miss a shift. Chainring sizes start at 27 teeth and go up in 1 gear increments. This is an excellent configuration for the all purpose rider.
High Speed Drive – 2.5x gear magnification. The High Speed Drive is for the speed freaks out there who still need to deal with hills. A 2.5x gear magnification gives you a very large top gear, which can be very nice on velomobiles, faired recumbents, ebikes and anything that goes fast!