The 2019 E-Bike went through three prototype drivetrain configurations before the final design was implemented.

Final Design

Battery Technology

The culmination of the prototype drivetrains determined the cost vs performance of two battery types, specifically seen in Prototype II and Prototype III. Prototype I was meant only to test the mechanical drive itself, not practical performance.

It was evident that both battery technologies, SLA and Li-ion, were enough to drive the DC brushed motor. However, as both test batteries were roughly the same size, practical testing showed the Li-ion battery out-performed the SLA battery in both distance and weight, although being the more expensive of the two options. This is due to the higher energy density of the Li-ion chemistry.

Li-ion battery technology was chosen to construct the final battery as a result, since distance and low-profile form was the main objective for this project, despite the extra cost.





Mechanical Drivetrain


The drivetrain integrates both an electric motor and the original pedal cranks as a source of mechanical power. The 450W brushed DC motor is mounted with a triangular bracket to the chain stay and the seat stay. It's output is mechanically coupled to the rear wheel by a sprocket fixed to the rim, and a chain connecting it to a freewheel mounted on the motor.

This freewheel works as a one-way clutch, allowing the bike to coast when the motor is not powered, as well as allowing the pedal cranks to still work in the stock configuration, and with the gearing still functional.

Because this design uses a brushed DC motor, the brushes will eventually have to be replaced after a high amount of runtime. Otherwise, maintenance for this vehicle is extremely low. The drivetrain should be kept lubricated for maximum efficiency and the battery should be stored in a cool and dry area at about 40% SoC to extend its lifetime, when not in use.

Electronics and Mounting



Construction/Fabrication

All fabrication such as CNC engraving and sheet metal cutting was done in my workshop, mostly from 1/8" 6061 Aluminum sheet metal. The bike frame, wheels, and rear gear cogs were not custom made.

The plate above the rear wheel was designed as a temporary battery hold (as seen in the prototypes). However, it was kept in the final design to work as a location for the rear lights, and to serve as a fender.

The rear fender plate is connected to the bike using two side supports that are bolted into the frame near the rear wheel axle, and is also connected to the junction box under the rear of the saddle. These custom parts were designed as one assembly and depend on each other for structural rigidity, another reason why the temporary battery hold was kept in the final design.

Other noteworthy assemblies include the LED bar running light, the control panel/name plate, and the 2-to-1 brake line assembly.

Gallery



Future plans

A second version of the e-Bike is planned. Version 2 of this project will be addressing the weak points discovered in Version 1, specifically (Ordered from greatest to least improvement significance)

• Battery life
• Suspension and tires
• Motor type
• Battery mount
• Brakes
• Mirrors
• Custom electronics

Battery life on the V1 is satisfactory, however this could be improved to store a larger battery pack in a more efficient integration with the bike frame.

Ideally the second iteration of the bike would also include a removable battery. However, there needs to be more design and testing efforts in order to determine if this is more practical. The current battery mount mechanism uses re-usable industrial strength ties, which is a royal pain to take on and off. If the removable design is kept, this mechanism will be thoroughly redesigned.

The battery pack itself is planned to be designed and assembled from the ground-up in the next version, as opposed to this project which uses 3 manufactured battery clusters. 18650 Li-ion battery cells will be used to create a large battery cluster to power the bike, ideally using more energy dense cells than the manufactured packs and a more useful layout to pack as many cells as possible.

There is no suspension in this design. Exploring suspension options on the next design will result in higher ride quality and more off-road capability. Tires should be upgraded in the next design.

The current brushed DC motor can be replaced with a brushless DC for higher life expectancy, lower maintenance, and lower audible noise. The current motor's brushes will eventually need to be replaced and is loud. The drawback to a brushless DC motor is the method for driving the motor is more electronically complex.

It is currently undecided whether the next motor will be an increase in output power or retain the same power output. Going over 500w will no longer classify the bike as an "electric bicycle" under Ontario legislation.

The rim brakes are adequate for this design and perform well. Other options will be researched for the future design especially if the power is increased. Side mirrors are also a consideration in the next design.

Custom electronics on the next build are only a conceptualization and are not currently planned. The skill, time, research, and cost involved in making custom electronics (motor driver, battery management, user interface, speedometer, light controls, etc.) is a resourcefully demanding task, especially when cheaper manufactured solutions are already available as parts for purchase.

This project started with the idea and layout drafted on paper, as well as the pinout for the LED halo fan that inspired the center piece of the front panel, also serving as the primary method of cooling.

The layout idea was brought to life via CAD software and physical layout. The CAD software was used to create engravings in a couple of the parts (nameplate, wire plate, etc). The physical layout started with two sheets, one of aluminum alloy and the other being clear acrylic for the front panel.

The layout for the aluminum mounting board was not necessary to draft in CAD, as the holes were marked with a marker after placing and leveling the computer components onto the sheet. It was then cut to size, drilled, and sanded for a brushed finish.

The acrylic panel was drafted in CAD to locate an optimal position for the center fan and the nameplate, which are the only two components mounted to the front panel.



Construction

❮ ❯

Most of the build uses machined aluminum parts with 6-32 UNC bolts. There are two 3D-printed parts, the PSU mounting brackets and the 4-bay hard drive dock. Both parts were designed in SolidWorks for this project.

Gallery

Code

The entire website is coded and designed from scratch without the use of any 3rd party code or template. Only HTML, CSS, and JavaScript were used to create the website. Everything was learned from experimenting and online syntax references, especially www.w3schools.com.

Because of the simplicity of the website, all CSS styling can be condensed in one file - with lots of organization to prevent getting lost in the code. Style parameters are organized by page, and in order from top to bottom of each page.

The code itself was written using a program called Sublime Text, an editor for programming and text files.


Icons



Font

Many fonts are used, however the main distinguishing font (as seen in large titles) is called Good Times, created by Typodermic Fonts at www.typodermicfonts.com.

A web license was purchased for the authority to embed on the website

Construction Phase

The domain name ("seangibson.ca") was purchased over a year before the website went live. For that duration, the "construction phase" was active, and the website displayed the following dialog for the entirety of the year 2020. The website was being developed during this time.



Final Version

This project is in early stages of development and currently does not have any prepared presentation.

Check back later for progress updates!