Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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CYCLING GEAR SHIFTER WITH MOVING CASSETTE

BicycleCyclingElectronic shiftGear shiftMoving cassette

Introduction

The system implements a gearbox for chainring-chain-pinion systems by translating the sprocket cassette instead of the chain tensioner. Allows the implementation of the movement without encumbrances in the radial direction, to be also applicable directly to the wheel hub. The electronic management through servomotors with feedback control allows high speed and accuracy of the change.

Technical features

The sprocket cassette is housed on a sleeve that slides on a splined shaft. The chain tensioner no longer acts sideways as a gearbox, but only keep the chain tension while remaining aligned with the main chainring. The implementation is carried out by means of one or more servomotors mounted on the sleeve and managed through a mainboard and a micro-controller (Arduino, Raspberry Pi or similar). When the rider presses a handlebar switch (eg lever or pushbutton), the micro-controller verifies that the gearbox has not already reached the extreme in the required direction and, if not, sends a signal to the mainboard, which actuates the servomotors. These act on the pinion-rack system, determining the translation of the sleeve and the pinion cassette up to the position memorized during the preliminary calibration.

Possible Applications

  • Upright bicycles for road, mountain or other use
  • Electrically assisted bicycles;
  • Recumbent bicycles;
  • Velomobiles.

Advantages

  • Increase in efficiency of the transmission thank to the constan alignment of chainring-chain-sprocket and chain tensioner;
  • Increase in accuracy and speed of the shifting;
  • A more compact system implies less aerodynamic drag from the sprocket cassette at higher speeds;
  • Linearity of the axial movment.