As a result of many factors (lack of money, no available workspace, academic responsibilities, etc), the bike project came to an early demise. It's not that I wouldn't still like to learn more about bicycles by taking one apart and it's not that I don't still need a faster method of personal transportation, but my interest will have to be limited to casual research for the time being.
While I worked at Agira Photonics from July to December 2018, I primarily biked to and from work. A preliminary look at my Apple Watch outdoor cycle workouts from the month of July only tells me that I biked 126 miles for almost 16 hours. Imagine if I had had an electric pedal-assisted bike! I could have avoided a lot of sweaty mornings in the summer heat. A one way trip to Greentown Labs from Northeastern's campus was about 3.75 miles for a time of about 30 minutes. I was lucky that the trip was relatively flat, too. Still, I would have loved to cut that commute time down to 20 minutes but that would have meant exhausting myself before I even started the workday. I learned some valuable lessons about in Boston over my 6-month career as a cyclist commuter. Most importantly, I'm grateful for the addition of bike lanes to many of the roads I frequently used. I felt safer that cars didn't feel the need to pass me and there was rarely "traffic" from other bikes. In contrast, on the occasion that I'd be running an errand through the Fenway-Longwood area, I felt too exposed to traffic. The roads themselves would be in bad enough condition that I'd have to swerve out of the shoulder to avoid potholes but there were multiple types of vehicles also using the roads. With all the Longwood medial buses, MBTA buses, ambulances, and regular cars in the area, I'm surprised that more hasn't been done to make traffic flow more smoothly. Biking in Boston is the bravest thing I do; it's not for the faint of heart. I plan to continue biking whenever possible, or until public transportation becomes more extensive. I hope to revisit taking apart and building back together a bicycle, but for now my attention is taken up by finishing my last semester of undergraduate education and finding post-graduation opportunities.
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My dilemma of finding a suitable bike to use (on the cheap) has been found! Sadly, it comes at the cost of my dear roommate's bike's demise. Seems like it was backed into by a car while locked up on campus and the back wheel got decently smooshed. She hadn't really been using it and she graciously offered to donate it to my project.
He suggested that I look into local recycling plants that will often sell you buckets of batteries for cheap with the idea that some of them may work and others may not. This would be a great option over buying one huge battery for both saving money and gaining a better understanding of how batteries work. Of course, there's potentially more of a safety risk using questionable batteries, but I'll enlist the help of my more experienced EE friends to make sure I don't blow anything up. Since my battery needs depend on the motor, and the motor depends on the bike (for the most part), it appears that the next step is to find a motor. The convenient coincidence is that in my Systems Analysis and Circuits classes this semester, we've just begun to talk about DC motors. Based on the preliminary research I've done, I want to look a motor that I can incorporate a torque sensor into. A torque sensor would make the motor "smart", in the sense that it would give more juice when it senses the rider applying more torque (going faster or going up a hill). I do want this pedal assist feature above anything because I want to be as safe as possible while riding this bike. An electric bicycle with a motor that's just either "on" or "off" starts to stray into motorcycle territory to me, and that's really not what I want. I still want to use my bicycle as a source of exercise and not take away pedaling altogether. The website The New Wheel is proving to be an incredibly useful source. I'll be looking for second opinions but their comparisons of different e-bike motors will give me a good starting point. Some motors available like the models by Bionx and Bosch have torque sensors built in, but you need to shell out some extra cash for the fancy ones. Could I integrate a torque sensor of my own? How does a torque sensor send signals to the motor? I need to know much, much more before I narrow down my motor options. I'd like to DIY as much of this as possible so I'd prefer to make my own, but I'm concerned about feasibility. The question of hub motor vs drive train motor is still up in the air, but with a torque sensor being a priority, I can push off that choice until later. An aside:
I'm getting a bit ahead of myself here but I'm thinking about how I'll need to make this whole system waterproof. I want to design a case myself and 3D print it. The students I mentor in the freshman engineering class will be doing a project exactly like this in a few weeks (to house an arduino and breadboard), so the timing works out well. I want to make sure that the case can keep splashes out but not prevent an air intake for temperature control. I believe that I'll have to make sure the batteries and motor don't overheat, or melt the plastic of the case, but I really don't know at this point what kind of heat I'll be dealing with. It's amazing, the more I learn, the more I realize I don't know. I'm going to interrupt my progress for a little while to do some much needed research. The last lecture in my advanced writing class was about literature reviews and their importance to both their authors and the field they explore. One of the initial steps of writing a literature review, my professor pointed out, is that you read *literally* all literature that exists on a particular topic to write a proper literature review. That being said, the scope of the topic can be very narrow or on such a leading edge of science that not much literature exists, but it got me to thinking that I ought perform a literature review myself on the topic of electric bikes, so that I'll understand what I'm getting into.
Luckily, I can kill two birds with one stone this semester as one of the assignments in the advanced writing course is to write a literature review on a topic of my choosing. I'll need to focus in on one particular aspect of e-bikes, as trying to write a literature review on the phenomenon of electric bikes would be an undertaking too large for one semester. I haven't decided yet what nook I'll focus in on, but as the first draft is due Friday, I'd better get going! I I am now the proud owner of my very first Specialized bike, a used Vita that I found as a great steal at a local bike shop. I didn't realize how clunky and impractical my bike was until I saw what this Vita had to offer. It's a step-through frame size that actually fits me instead of a too-small, men's bike. It's about twice as light as my current bike, which is perfect for dragging up multiple flights of stairs in a Boston apartment building.
Purchasing a new (to me) bike has better illuminated my needs for an electric bike. I don't think I'll be using this Specialized Vita for this project. Ideally, I want to find a bike that's:
Another item I need is a large battery. I heard through the grapevine that a particular club at Northeastern has some spare lithium ion batteries that I might be able to borrow for making my e-bike. A peer who has experience using big batteries told me that my battery needs are going to depend on the requirements of the motor I choose. The motor I choose is going to depend on the payload I anticipate (weight of me, the bike, and whatever I carry on it). According to Evelo Electric Bicycles, two commonly used types of motors for electric bikes are mid drive or hub drive. The main distinction between a mid drive and a hub drive motor is that a hub drive motor is attached to the hub and drives the wheel of the bicycle directly, but a mid drive motor is inserted in series with the drive train and drives the crank. I am a student, which means that my most limiting factor in this project is cost. A comparison guide from E-Biking Now claims that hub drive motors are more readily available and cheaper, and that mid drive motors can be proprietary. I'd like to do as much of this project by my own construction as possible, so for that reason, I intend to choose a hub motor, but my mind isn't set on it yet. The website warns that the handling of a bike with a hub motor can be affected due to a raised center of gravity, and I worry that handling is something I need while weaving through pedestrians and cars in Boston. In my next post, I hope to have secured down a battery and reached a final decision on a motor and motor configuration. All logic may fly out the window if it turns out that my cost considerations lock me into one option or another, whether that be the battery capacity or motor cost and availability. For a while now, I have been looking for a project that would be technically challenging and a good exercise of my creative skills. About 18 months ago, I brought a bike to Boston with the intent of using it as transportation from my apartment a mile away from campus to daily classes. As my comfort level with biking grew, I discovered a new freedom to explore the city without being limited by the cost of public transit or pre-determined routes. It was then that I decided I wanted to build my own bicycle, from scratch.
The first step in this process was to learn how to weld. I sought out welding classes in the Boston area and stumbled upon the resources of the Artisan's Asylum in Somerville. I took a 3-hour MIG welder class that introduced me to the basics of welding technique. In no way am I prepared to weld together a bicycle frame, but I better understood the difficulty of my intended project. Summer classes and fall classes stalled any progress I might have made and this idea got put on the back burner. In the meantime, I moved back on campus and don't use my bike as often, but I use it for longer trips to destinations in Boston. The deficiencies of my current bike were made apparent when I decided to sign up for Postmates, a delivery service, and was losing money because I was too slow to drop off orders. My bike is probably 25+ years old but was not maintained well before I acquired it. The derailleur is on its last legs and would cost more to replace than the whole bike is worth. The small hills of Boston become more like mountains when I don't have full use of all of the gears. On top of that, the bike frame itself is too small for me, so using it for extended periods of time puts a lot of pressure on my wrists. My new idea is multi-faceted: I would like to get a new bike that fits me better but also retrofit it with an electric motor to help me get around Boston faster. Initial research leads me to think that a pedal-assist attachment is going to be better suited to my needs, but I'll need to do an exhaustive search when I start looking for good places to purchase the parts I need. An electric bike hack would satisfy my original goal of being technically challenging, as this would be my first ever independent project. I hope to learn more about motors, gears, and bikes in general, and boost my confidence as a budding engineer. I know hardly anything about electrical systems or batteries, so I anticipate that I'll have to source out some advice from some EE comrades. Next post will be a better outline of the scope of the project, anticipating problems, and identifying a starting point. |
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