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The Schlumpf Speed Drive is an internal overdrive gear system that can be used on the front or bottom bracket of a trike or bike. They eliminate the need for having a front derailer, shifting components on the handles, or cables coming from the main bracket. Schlumpf makes multiple types of Drives all with unique gearing ratios. The Speed Drive is their base model, and takes whatever base gear that is installed on it and increases it when overdrive is engaged by . So for me, my 30 tooth gear instant
