Our Mission:Our mission is to expand Citi Bike’s target market to encompass ADA accessibility and injured riders by integrating an automated stabilization system into their entire fleet.
|
OverviewOur system is made up of two rolling stabilization legs that thread onto both sides of the rear axle (similar to training wheels). Each aluminum leg is powered by a DC motor integrated with a self-locking worm gear system, programmed to rotationally retract and deploy at certain speed thresholds. As a Citi Bike rider slows to a stop, our legs will deploy at approximately 3.5 mph, thanks to a speed sensor, preventing the bike from toppling over and eliminating the need for the rider to take their feet of the pedals. Similarly, as the rider begins pedalling, our legs will retract at the same 3.5 mph speed threshold, giving the rider a conventional bicycling experience.
|
DesignOur design has undergone many iterations before arriving at the current state, shown below. We wanted to create a mechanism that would provide the automatic stabilization desired while still being aesthetically pleasing, lightweight, and functional. We implemented a worm gear driving system for its self-locking geometry and for its overall design simplicity. The motor is recessed into the leg and secured by hose clamps to align our drive and worm gear. We strategically placed holes to minimize weight and retain strength. The wheels are slightly elevated off the ground, similar to traditional training wheels, allowing full deployment of leg without interference with the ground. An arduino, GPS speed sensor, and limit switches control the deployment and retraction of the legs, which take approximately one second, ensuring stabilization before complete stopping and destabilization occurs. By incorporating a lithium battery, we can achieve a lightweight source of power as well as provide a significant number of deployment - retraction cycles on a single charge.
|
ImplementationThroughout the process of exploring a specific industry niche that could be fulfilled, as well as engineering and optimizing a solution to fit this need, we realized that there was a third aspect that should be addressed: successful implementation. Citi Bike currently has 12,000 bicycles in their fleet, with many more being scheduled to enter the industry in the near future. Our device simply attaches to the rear axle - no future modifications are required to the bike. From a business perspective, this ultimately creates a system that could be efficiently and inexpensively integrated into their growing fleet without any Citi Bike design changes. After speaking with several wholesale suppliers and injection molding companies, we found that it would cost approximately $450,000, plus labor for attaching each unit, to manufacture 15,000 units. Specifically, ICOMold, an industry leader in injection molding, stated that it would be $150,000 to create 15,000 units out of a high strength engineering resin. We also spoke with general wholesale companies who stated it would be approximately $20,000 to complete each unit with the necessary wheels, bearings, and the other hardware. Lastly, we found that it would be approximately $280,000 to obtain the necessary electronics, such as the battery, control units, and limit switches. We chose 15,000 units as our target lot number so that Citi Bike’s entire fleet could be fitted with these mechanisms, as well as account for future growths of it or repairs. With the monthly revenue that Citi Bike creates, this system could be implemented well within one quarter and it is estimated that it would reach a 10- 12% broader audience.
|
|
About Us
Designed by 4 Mechanical Engineers from Columbia University