The Electric Motor Bike

For my project, I decided to make an bike powered by an electric motor. My first goal was to first make a bike with a motor not directly touching the wheel, but through a system of gears which I have not reached to yet, but I am starting by having the flywheel rotating the wheel. Right now I am at the stage of beginning to design the structure holding the batteries to power the motor and I am going to make the toggle clamp for the lever.

First I had to get the materials needed for the project. I first got treadmills to disassemble from people who did not use them anymore to get the electric motors. Then I scrapped down the treadmill to save some materials that could be of use like the control system. I then got bikes that were either donated or I old bikes that I owned but are not as used. Finally, I obtained left over bars of aluminum from a previous project to use them to make the frame to support the motor when it is attached to the bike along with the 1/4 inch and 1/8 inch nuts and bolts to connecting them together.

There were a few changes I had to make with my bike when making the lever to the bike. With the original frame of the seat post of the bike seat being short and being unable to extend it further to be set for my height, I had to get a new tube that could both hold my weight and be able to drill through, without the threat of it crumpling due to the weight put on it. With the longer seat post I would be also able to raise it either higher or lower if needed for people who were around my size. After searching through leftover scrap metal in the shop, I found a tube that was both longer and thicker than the old seat post, being 1/8th inch while the other was less than 1/10th of an inch thick. Some parts of the bike were also old and damaged and so I replaced them with better parts that were not as damaged like the child seat, that had tears, for an adult seat that had less damage and was more suited for my body.

When beginning to design the electric motor bikes with the materials in mind, I decided to draw out my first design by having a lever system with a pivot point connected to the seat post. After designing the lever system, I designed a toggle clamp using Solidworks for my first approach. All of the parts for the clamp were put in as an assembly, but I still need to look for a way to provide pressure so the clamp can lock in while the motor is raised and not have the danger of falling down and possibly causing an injury to the rider or the bike. I then made calculations for a curved cut for lever's arm to hold the motor. This was designed so the motor body could sit in the cusp and not have the danger of the bolt to experience a lot of force when it is attached to the arm while riding. I first calculated the width of the cut for a 1/4 inch deep cut, and a 1/2 inch deep cut if needed, using Pythagorean theorem.

After organizing the aluminum with what my group all needed, I began with making the back wheel frame part of the bike. I began by using a hacksaw and filer to make grooves so I could slide them into the frame of the bike, and to have them avoid moving parts of the bike like the chain. This was also considered for the lever system as I needed to make a grooves so the arm could latch onto the back frame to only have the flywheel touch the wheel, without the whole weight of the motor pulling down onto the back wheel and producing too much friction for the wheel to spin. I also had make sure that I did not make the grooves to big or have only a small joint connecting a bar, as the low density of the aluminum could make it easier to break with the weight of the motor and the shock it will absorb from the impacts from rides it will have.

To make the lever, I used 2 ft aluminum bars to make the arm. I first connected them to together to form the arm with the lower bar connected to the seat post. This would have the higher bar act as the latch and have the lower arm closer to the wheel to have the flywheel touching it. I then drilled the hole into the lever's arm and the seat for a bolt to connect them together. I then cut off about 1.5 ft of the top bar, using the metal chop saw, as it stuck out from the bike ad was unnecessary. After the cut, I made a groove into the top bar using the hack saw and filer so it could catch onto the bike frame.

To make the curved cut in the aluminum bar to hold the motor, I used the milling machine with a rotational table. I had to first prepare the machine to follow my motor's ~9 inch circumference path. To do this, I made a 3 inch diameter circle to set a pivot point for cutting into the bar, and I then used some small pieces of scrap wood to follow the cutting path. First with a 1/4 inch wood piece to have it to above the rotational table to prevent the 1/2 inch bit from touching it and then a 3/4 inch wood piece wedging it between the chuck perpendicular from it to the other two parallel to it so it could follow the path. I then cut down the bar by moving by small increments down the y-axis to the bottom while resetting it every time to begin cutting in the same direction to prevent the bit from being damaged. I did experience some trouble as the aluminum gripped onto the bit and pulled it out of place and I had to re-center it while having some bit markings on the inside. After finishing cut, I drilled a hole for an 1/8th inch bolt to connect it to the motor.

The belt is not required but it will help grip onto the tire but it makes a lot less chance for the tire or flywheel to slip off and loose contact. To make the belt I used one of the leftover bike wheels and trimmed off 9 inches of the tire's tread and then trimmed it down more so the width of the belt would line-up with the flywheel. I had to sand down the fly wheel to provide more of a rougher edge for the glue to set on with the tread and not have the rubber tread slip off because of the smooth surface. This concludes where I am with my project