Jul. 29, 2024
Automobiles & Motorcycles
Each year EVELO brings new and constantly improving electric bikes to market. These bikes are specially designed to meet customer needs. Recently, John O&#;Donnell, who is responsible for product design at EVELO, joined us for a podcast.In the podcast, you will learn about John&#;s background, the EVELO design process, and bicycling industry manufacturing and design trends. You can listen to The Electric Bike Podcast from EVELO and read along with the transcript below.
With competitive price and timely delivery, Keren sincerely hope to be your supplier and partner.
Armando: Bicycles and even electric bikes seem pretty simple. There are a frame and some pedals. What else do you need, right? There are some nuances, some challenges, some interesting little tidbits that make the bike industry fun to learn about.
My name is Armando Roggio, and this is The Electric Bike Podcast from EVELO. I&#;ve asked John O&#;Donnell to join us. John is responsible for product development at EVELO Electric Bicycles, and we&#;re going to learn why electric bicycles &#; and really almost all bicycles &#; are manufactured in Asia. Hint, it has to do with supply chain and market size. We will talk about what goes into designing an electric bicycle, and perhaps, by the end of this podcast, you&#;ll know more about how the industry works and what really electric bikes are and maybe even why you&#;re interested in them.
John, would you mind starting us off by telling us what is product development or, really, what do you do for EVELO Electric Bicycles and, perhaps, describe some of your background in the bicycle industry?
John: Sure. I head up the product team here at EVELO, which handles all the product development, basically from the design to implementation to actually getting the bikes in the warehouse, so all the steps along the way. Obviously, we&#;re a small team, so everyone wears many hats, so it&#;s anything from picking up the for a warranty or sales questions to traveling over to Asia to do QC on the bikes and everything in between. That&#;s my role here now.
As far as my background, most of my adult life has been spent in the bike industry. I&#;ve managed a shop in D.C. many, many years ago, and then, from there, actually went over to what at the time was Univega, one of the Raleigh brands, and during my time there, I also did lots of different things from basic customer service to managing an inside sales staff to working as an outside rep, and saw a lot of changes there during my time there just not only within the company, but within the bike industry because it&#;s right around the time that the move from production in the U.S. to Asia was being finalized.
John: An interesting thing, Raleigh was actually one of the last manufacturers of domestic bikes that were at a reasonable price point. There were some specialty manufacturers doing high-end stuff, but, at the time, we were one of the last people making $200 bikes in the U.S., and it was around that time that Bill Austin actually ended up moving production from Kent, which was where we were located, over to Taiwan, and it was interesting because I got to see the production facility. It was actually right next to our office, so we got to see exactly what was going on. I got an early taste of the production side of things then, and so it&#;s interesting to see how it&#;s come full circle, traveling to Asia and seeing the bikes made over there.
Armando: What was the driver that moved bicycle manufacturing to Asia, and what&#;s the reason, I suppose, that so much bicycle manufacturing is done in Asia?
John: I can tell you first hand that the driver at Raleigh wasn&#;t cost, which I think is the first thing people think of, that it will drive the price down. The big thing was lead time.
Our factory was literally across the street, and we would basically place orders to the factory and they would produce the bikes for us, and lead times were generally 180 days, best-case scenario. Sometimes, they would run all the way up to 360 days, and although that sounds ridiculous, I got to see&#; again, see first hand how one part not being there would just shut the assembly line down, and, whereas in Asia, if you are out of front derailleurs, you can put them on a cart, drive them over to the factory, get the production line back up. Back then, air shipping was prohibitively expensive, and pretty much everything involved, putting it in a containing, shipping it overseas. All the supply chain is in Asia, China, Taiwan, so that was a big part of it was just the lead time.
The other thing was the level of assembly. At the time, it was pretty antiquated. It was a legacy factory that we kind of Band-Aided together. The factories over there were newer, more modern, more automated, and the end result was that our customers at the time were getting a much higher level of assembly on bikes from companies that were producing overseas, and we would get feedback a lot of times from dealers that it would take anywhere from 45 minutes to an hour to build one of our bikes, whereas competitors&#; bikes, Trek, Specialized, they were putting together in 15 to 20 minutes, so lead times and level of assembly were really the two big drivers for it.
Armando: The fact that most of the supply chain was already in Asia and the idea that the decision was maybe to go to Taiwan because of lead time, these things seem like symptoms or indicators of something larger, so could it be market size? Is the consumption, if you will, of bicycles greater in Asia than in the U.S. or the E.U.?
John: By far, that&#;s one of the reasons that the sub-suppliers have been over in Asia. I don&#;t have the exact numbers in front of me, but it&#;s several orders of magnitude larger over in Asia and in Europe, to a lesser degree, than the U.S., so, consequently, that&#;s where most of the derailleurs are produced then.
We&#;re really a niche market for the global bicycle industry in the U.S., so, yeah, from derailleurs, tires, spokes, you&#;ll find some high-end specialty stuff that to this day is still made in the U.S., and even that seems to be less and less as more high-end suppliers go offshore, but for large production of basic bicycle components, things like chains, spokes, rims, tires, we&#;re doing so much more volume in Europe and in Asia than in the U.S. that all of the sub-suppliers have moved over there. I honestly can&#;t remember the most recent derailleur, front or rear derailleur, shift cables that have been made in the U.S. It&#;s probably been I would say since the &#;70s that when Schwinn was manufacturing in Chicago that the sub-suppliers were actually producing stuff in the U.S.
Armando: Okay, so, this year, EVELO has introduced some new models, the Aries hub-drive, the Aries mid-drive, the Aurora hub-drive are all examples, but given that all the sub-suppliers and all the manufacturing is done in Asia, how do you bring a new bike model to market here in the United States?
John: Actually, it starts with feedback from the customers as far as trying to design something that folks want, so it really does start as a clean sheet of paper and trying to figure out what we&#;re selling now, what people like, what they&#;re looking for, and then, once we wrap our head around a design that people want to ride, then we start from there, design the frame, pick the components and then source all the parts.
It&#;s really a collaborative effort. We do the basic frame drawing and then work in conjunction with the factory&#;s engineers to finalize the drawing. There&#;s always a bit of a divide between what you want and what the factory can efficiently produce and they&#;re not always necessarily the same thing, so there&#;s a fair bit of work on that side of things, tweaking the frame design so that it&#;s something that can be produced efficiently and work for what we want it to do.
After the frame drawing is done, we basically go through every single nut and bolt on the bike and then decide what parts are going to be on there, and we get feedback from multiple people on the team to decide not only what people or what the end users are looking for, but things like ease of service out on the field is always a consideration as well. We want to make sure that not only is it a good bike to ride, but if it does need service, servicing can be done relatively easily. Things like the position of the motor housing, like how easy is the controller to get to on the bike, all of that sort of stuff is factored in, and, yeah, so it&#;s a pretty big project because, obviously, there are tons of moving parts on a bike, from the bike design to the box that holds the tools that are shipped with the bike, to the packaging, which is also another big part of the process. All that has to be figured out before anything runs down the production line.
Armando: As you are working through a new electric bike design, are there some known problems or bottlenecks where you always know this is going to be a challenge, or is each new electric bike design is sort of its own adventure?
John: A little of both actually. I mean, every time there&#;s the first production of something, it brings some new challenges. That said, there are things that are always going to be a challenge. For us, especially since we ship direct to consumer, one of the most tricky things is packaging because, when a bike shows up to a bike shop, the first line of defense is going to be the shop unboxing the bike and, potentially, fixing anything that goes wrong in shipping.
The other thing is how the bikes are shipped is a bit different when you&#;re shipping to a bike shop versus shipping to an end user. Typically, if a bike ships to a bike shop, the shop will normally order 15 to 25 bikes at a time, and they&#;ll show up on a pallet, shrink-wrapped, and it&#;s a lot more safe environment for them to travel. In our case, we&#;re almost always shipping individual bikes, and they&#;re going by individual carriers such as FedEx or UPS. They lead a harder life en route to the end user. There is no way around that, so packaging is one of those things that we&#;ve done really well with. That&#;s always a moving target. We&#;re always trying to improve and makes sure that the bikes arrive as good as possible.
Armando: The solution I&#;m guessing is not to include more bubble wrap, right? You&#;ve got to be more efficient than that.
John: Correct. It&#;s funny when you asked that. At one point, we were throwing more and more foam at the equation, and it actually worked pretty well, but the end user experience was pretty poor when they would be covered in this foam that would be broken into millions of pieces when they pull the bike out of the box. You have to balance getting the bike there in one piece with not wasting a ton of resources and making it a positive experience to pull it out of the box and build.
Fortunately, particularly the factory we&#;re working with right now, they brought a lot to the table in terms of ideas on packaging, so we were able to use not a ridiculous amount of packaging to keep it in the box, but also do a good job of getting it there. Also, things like the quality of the box, it&#;s not something you really think about, but there are different levels of cardboard. Some of the boxes use a very, very high level of recycled cardboard that&#;s really soft and is a lot more prone to damage in transport, so using higher quality cardboard or sticker box ends up paying some pretty big dividends in getting the bike there in one piece.
Armando: What about getting the bike in the box? You have a product that is going directly to the consumer. You want to make it relatively easy to assemble. How does that impact your packaging?
John: That&#;s a good question. It&#;s one of the things that I think most people don&#;t realize is that all of the bikes are actually fully assembled and test-ridden before they actually go into the box. That is actually not typical from the normal production situations particularly on bikes that are shipping to a bike shop. Those bikes are normally not 100 percent assembled. They&#;re actually built as they go in the box.
In our case, the bikes are completed, standing in a row for us to test ride and then are broken down and then put back in the box. One of the big advantages there is that you&#;re able to check things like shifter adjustment, brake adjustment, make sure the wheels go through. It basically reduces the amount of time that the end user has to get the bike together and increases the likelihood that, when it&#;s put together, everything works correctly as it should, so&#; but it also makes for extra steps for the factory.
In terms of how it goes from that bike to being put back in the box, it actually goes back on the assembly line for packaging, and there&#;s a dedicated line that&#;s just for that, and, at that point, it&#;s disassembled to a point where the customer has to then put it back together. It&#;s normally pretty straightforward stuff. We pull off the front wheel, pull off either the stem or the handlebars and then pull off the pedals. All that stuff is put in the box, and then the protective wrap is then put on the bike and then put into the box.
Armando: Obviously, EVELO doesn&#;t make conventional bicycles, but rather an electric bike. Would you describe the difference?
John: It really starts with the frame. There are different ways obviously to make an electric bike. With ours, the frame is actually a purpose-built electric bike frame, and I think you&#;re seeing that across the industry more and more. When we started seven years ago, it was a bit different in that there were a lot of bikes out there that were basically conventional bikes with the motor stuck on the back, but there&#;s a lot more power going through the bike, so, having the frame, spokes, tires, all of that stuff being operated for the extra weight that you&#;re going to be carrying with an electric bike and the extra power, all of that stuff is a consideration.
Besides that, I mean, the basic parts are actually the same but will be more durable. Take, for instance, spokes, they look the same, they&#;re just going to be a heavier gauge. Same with rims, the extrusion will be a little bit thicker, so that it will weigh a little bit more, but it&#;ll be able to withstand the extra weight of the bike and the extra power that&#;s going through it. The basic bike components, for the most part, are similar, just built a little more durable, and then, the electric components, that&#;s obviously something that&#;s specific to the e-bike, which should basically be comprised of the motor, the controller, the battery, and then the display panel.
Armando: You mentioned the trend toward purpose-built electric bike frames in the industry. What are some of the other trends you&#;re seeing in electric bike design?
John: I think more and more folks are realizing the benefit of a mid-drive design. I know, when we started, we were one of the few in the U.S. selling a mid-drive bike, and now I think it&#;s generally accepted that, for the most part, a mid-drive is more preferable. It comes with an extra cost because, again, you need a purpose-built frame and motors. It&#;s little more complicated than just sticking a hub motor on the back, but there are a lot of benefits to it, and, now, you&#;re seeing more and more companies that are incorporating a mid-drive.
In addition to that, I would say that things are being a little bit more integrated, having the bike look less and less like an electric bike. The first electric bike, when you would see one rolling down the street, it was pretty obvious what it was, whereas now the batteries are a little more in line with the bike, more and more center-mount batteries, so the battery isn&#;t included in the rear rack. We still do one model that has that because it offers the advantage of having a really, really low step-through height, so it offers the easiest on-off access than any bikes that we have, but, for the most part, batteries are migrating towards the middle of the frame. Motors are migrating towards the middle of the frame. I think those are the biggest trends right now.
Armando: John, you mentioned step-through height. Why is that important for some customers?
John: I would say two reasons. First off, I think our average customer is probably a little bit older than we initially thought right at the beginning, like six years ago. At the beginning, I think our basic thought was that commuters, people using the bike as a car replacement would be really the biggest market, and what had turned out was there are a lot of Boomers looking for exercise, looking to get back into riding. People that used to ride, been off the bike for 15, 20 years, are looking to get back into it, has started to ride, and a lot of those customers are a little more limited in flexibility and they want the ease of access to get on and off the bike.
That said, I think there&#;s more to it with an electric bike. The bike itself, even a lightweight electric bike, is still going to be relatively heavy, and it is just easier to get on and off the bike. I mean, I ride a conventional bike. Most of my riding is done with a nonelectric bike actually, just a regular pedaling bike, but if I&#;m riding an electric bike, I prefer the step-through. It&#;s just easier to get on and off with a heavier bike. Even a lightweight electric bike is going to be anywhere from&#; They&#;re going to be roughly double the weight of a conventional bike, so it does make it easier to get on and off.
Armando: A key contributor to weight is the battery, so why not talk a little bit about battery technology, perhaps how it is evolving and where you think it might be going?
John: It hasn&#;t evolved as much as folks might think. For instance, the cells that were just introduced, everyone knows it as the Tesla cell, it&#;s an evolutionary product. It&#;s really not anything that&#;s revolutionary. It will basically take the weight of an electric bike battery from about eight pounds down to maybe six pounds for the same range or it will increase range a little bit.
For the last probably 10 years, the basic technology on batteries really hasn&#;t changed that much, and if you look at battery technology in general, it generally goes in cycles of about 20 years. When lithium-ion cells were first introduced, that got full acceptance and then gradually became the standard for all consumer products. Things like power tools used to be NiCad. Now, it&#;s almost exclusively shifted over to lithium-ion, but it isn&#;t a change that happened overnight. It was a long time in coming, and then if you go back before that, the lead-acid battery packs, it&#;s the same thing. They had a period of about 10 to 15 years where they were the standard for consumer products.
As far as where it&#;s going for the foreseeable future, I don&#;t see any huge changes. Things like solid-state batteries have a lot of promise, but we&#;re talking 15 to 20 years before there&#;s going to be something that&#;s going to be commonplace in not just E-bikes, but consumer products in general.
Armando: John, you&#;ve done a good job describing the electric bike production process, but is there anything else you&#;d like folks to know about how electric bikes are designed or made?
John: I think one of the things that&#;s worth discussing is the issue of cost because, obviously, and this isn&#;t just with electric bikes, but bikes in general, bikes can ranges anywhere from 10,000 and up, down to $200. There are obviously pretty big differences between the $200 road bike that you&#;re going to buy and the $10,000 road bike.
What I will say with electric bikes is you really don&#;t hit the law of diminishing returns until you get to probably four or $5,000. When you get above that price point, you start paying lots of money for small increases in performance, so, for the most part, if you&#;re making the jump with an electric bikes from, say, $500 up to about $4,000, you&#;re getting a commensurate increase in performance for the amount that you&#;re spending, and then once you start going above that, you&#;ll start spending a lot of money for small increases in performance.
Just to give you as kind of a for-instance, I&#;ve seen electric bikes through various online channels where the retail price of the bike is roughly the same cost of the battery, not what we retail a battery for, but our actual cost, so, obviously, if they&#;re doing a large volume, they can get some break on pricing, but they&#;re doing it by using lower cost components. It&#;s not necessarily a bad thing. I mean, if it&#;s people&#;s first entry into an electric bike and it gets them on an electric bike, that&#;s great, but if they&#;re using it regularly, chances are they&#;re going to run into reliability issues.
The other thing we run into pretty frequently is that we&#;ll get calls from customers looking for parts to service the bike that they bought online a couple of years ago from a company that went out of business, and, unfortunately, we rarely can help those folks because the bikes used proprietary parts, and so part of selling and serving electric bike is making sure that you have replacement parts in stock. From the bikes that we&#;ve discontinued and sold seven years ago, we still support out in the field. We still have replacement parts for them. That&#;s also one of the drivers of cost.
Armando: Makes sense. John, you have been great. I really do appreciate you for taking the time to chat today.
John: Hey, it&#;s my pleasure.
Armando: Thank you, everyone, for listening to The Electric Bike Podcast from EVELO. We want to cover topics that interest you, so, if you have suggestions for a podcast topic or maybe you want to share your electric bike experience, please us at . Let us know what you&#;re thinking. We&#;d love to hear from you. Also, if you want to learn more about electric bikes, please visit evelo.com and look for The Complete Electric Bike Buyer&#;s Guide.
Take care. Thanks again for listening.
Step-by-step through an electric bike conversion
By Henry Harvey
As a designer and motorcyclist, I had the idea of building an electric motorbike for a long time. The opportunity arose when I was in my nal year of an honours degree in industrial design at Victoria University. I rode a Honda VFR400 to my lectures and the bike started having engine problems. I pulled out all combustion-related components and sold them. By the time I had a plan for an electric motorbike laid out I was part- way through a post-graduate diploma in Computer Aided Design (CAD) at Christchurch Polytechnic. My electronics skills were almost nil and I didn&#;t know much about motorcycles either. But I&#;d had some part-time design work, worked as an apprentice in a workshop and I&#;m sort-of a wannabe engineer. I wanted the bike to show that I could do more than draw pictures and I hope it will help in my job applications.
Around this time my brother Edward was also in the process of converting a sedan to electric drive. His experience turned out to be invaluable. After selling all the parts relating to the petrol engine, I was ready to choose my major components: the batteries, motor and controller. I had to ask a lot of questions at this stage and directed many towards Iain Jerrett of Astara Technologies. Iain has built several bikes with AC motors so his experience was very helpful. In order to make considered decisions, I narrowed my use scenario. The bike was going to become a torque- happy commuter, capable of highway speeds but designed for city use. This was mainly driven by economics. A long-range vehicle would require more batteries, increasing cost while also making it more dif cult to t them in the relatively small aluminium motorcycle frame. Based on these restrictions I ordered the main components.
Batteries
For batteries, I chose 60 Ah Winston LiFeYPO4 (lithium iron yttrium phosphate) cells, which I ordered from EV Hardware. This brand has been used in a lot of conversions and while there are other more energy-dense batteries, Winston are well-known and reasonably priced. While lead acid batteries would have been cheaper up front, their short lifespan and poor energy density ruled them out. Because I had decided on a 72V system, I chose to use 28 cells. 3.2V per cell makes a series connected pack of 89.6V nominal. Although this is above 72V, it is not an issue as long as the controller is rated to handle it. Voltage &#;sag&#; occurs at high current draw so a higher voltage pack is a necessity for good performance.
Motor & Controller
As an electronics novice, I chose the safe option of buying the motor and controller as a kit from Astara Technologies motor is a HPEVS AC15. This is a 72V AC motor, rated to produce 68ft/lbs (93 N m) of torque and makes 27HP at rpm. The controller is a Curtis . It is capable of delivering 550A for short periods. These controllers are very programmable but this generally requires a handheld programmer or computer software which is an additional cost. It is frustrating that Curtis doesn&#;t include a USB programming cable with the controller, although Astara Technologies offered me the use of their programmer.
Charger
The charger was another important component which needed to be bought after I had decided on which batteries I would use. I chose an Elcon W charger with a charge curve programmed specifically to my batteries, with charge curves programmed above and below my cell count, in case I chose to add or remove cells. Other specialty components included DC fuses, contactor, emergency disconnect, state-of-charge meter, battery interconnects and many more. I also required a DC-DC converter, which allows me to drop pack voltage down to 12V, for the motorcycle&#;s standard low-voltage system.
Battery monitoring
I chose not to include an individual cell- monitoring system in my circuit as my battery pack would be bottom-balanced. All cells in a series pack have slightly different capacities. Because of this, they can&#;t all be expected to reach their full charge/discharge level at the same time. Bottom-balancing moves the cell imbalance to the top of the charge cycle where damage is less likely to occur. One of the easiest ways to damage a cell is during discharge when the weakest cell reaches 0V before the other cells. When this happens, the other cells will continue driving current, which effectively reverses the cell potential of the 0V cell, destroying it almost instantly.
When charging the pack near the end of the charge, cell voltages will be different. However, usually the charge current is ramping down at this stage anyway, and the voltage of the top cells will start going up quite fast, which raises the pack voltage relatively quickly to the point of charge cut-off.Generally it is quite safe for LiFeYPO4 batteries to reach up to 4.0V at the end of their charge cycle, as long as the charge current is not high and they are not held at this voltage for long periods of time. Bottom-balancing isn&#;t fool- proof. However, it can remove the need for expensive (and sometimes failure- prone) battery management systems (BMS). I made my decision based on recommendations and my own research. I will continue to check my batteries periodically and I am not yet in a position to endorse this method.
Bottom-balancing
To bottom-balance my batteries, I used aluminium strips with bolt holes in them to join the terminals in parallel. I placed a load across the circuit in the form of a large resistor element. Using a 12V contactor with a small battery, I could switch the circuit on and off. I placed a fan in front of the element to dissipate heat. It took around seven hours to bring the batteries down to 2.7V. Nearer the end I was constantly checking the voltage of batteries at either end of the pack. Several times I left the circuit off for 24 hours to allow the batteries to settle.
The first time the batteries are charged in series they need to be carefully monitored to make sure none of the batteries are of significantly lower capacity which could cause overcharging to that battery. Then in theory the batteries can be charged and discharged safely.
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Motor
After I stripped away all combustion engine-related parts, my first task was to mount the motor. It should be as close as possible to the swingarm pivot. As suspension sag affects chainline, I tried to match the new sprocket position in the vertical axis to the original sprocket position. I modelled the parts on a computer and got them profile cut from 6 mm mild steel. Milled aluminium would be lighter and look nicer but at the time I decided mild steel would be easier for me to work with and cheaper. Because my bike uses a single-sided swingarm, my sprocket options were limited&#;the swingarm bulge prevents a large sprocket being used. I knew from research that I wanted to get a drive ratio of about 1:5. This would give me a top speed of around 140 km/h and hopefully good torque. This meant that I had to use a 428-pitch chain to achieve a smaller rear sprocket diameter.
I theorised that because the bike had smooth power delivery and no gears, this pitch would be strong enough. I used a 12-tooth off-the-shelf sprocket for the front&#;any smaller and it is arguably hard on the chain and sprocket. This meant I needed a 60-tooth rear sprocket which I had to buy as a blank and get the hub pattern machined out. This was quite an expensive process for the sake of a fancy swingarm.
Fitting batteries
Once the motor and sprockets were mounted I had the most difficult spatial task of the whole project: fitting 28 batteries in without the bike looking like it&#;s made of Lego. After a lot of cardboard and wood mock-ups and one failed aluminium box, I finally found an acceptable solution. I decided I needed to still be able to have horizontal bracing through the centre of the frame, where the motor was once bolted. This limited my options and meant that I had to have two main boxes. The lower is made from angle iron and the top is 2 mm aluminium. The original box was made by a tradesman but in the end I had to cut it up and re-weld it myself after my plans changed.
The tubing that makes up the new stressed member is BS boiler tube with an outside diameter (OD) of 25.4 mm and a wall thickness of 2.90 mm. The main fixing points are made from mild steel round bar, bored to t 12 mm, high-tensile hex-head bolts. I think it&#;s fair to say that it&#;s overbuilt. Most of the welds are TIG. I purchased an AC/DC welder specifically for the project and it is fantastic being able to weld aluminium as well as steel.
Sub-frame
The original sub-frame was made from box section steel tubing. I decided to design a new sub-frame mainly because the old sub-frame would have needed to be heavily modi ed to t around the battery box. It also had many bosses and tabs for things like fairings and exhaust that I no longer required. The new sub-frame is made from 26 mm OD mild steel tubing with 1.6 mm wall thickness. I wanted to utilise lightweight tube with good triangulation design to create a minimalistic trellis structure. I had to make new threaded bosses for my sub-frame.
I turned down some mild steel bar on the lathe then bored and threaded four M10 x 1.25 thread bosses. My old South Bend lathe was used regularly throughout the project and has been a great timesaver as I live an hour from any machine shops. The high-quality tap was rather expensive but will be used again. The sub-frame was tacked and welded with TIG. It can be a bit tricky tacking with this welding process but with enough clamps and jigs it is possible. I found that my right-angle magnet totally destroyed my TIG arc and later found this is called &#;arc blow&#;.
Welding
Unless you are willing or able to make an accurate jig, it&#;s best to tack and weld the sub-frame while it is bolted in place. It allows you to have a better idea of how it ts visually but it also helps prevent the sub-frame warping out of shape. This can be further avoided by tacking tubes uniformly and evenly around the joins and also evenly on each side, jumping back and forth to even up welding stresses. First, I tacked up the main tubes to check seat height and angle&#;I carefully sat on the sub-frame and checked the ergonomics and made any necessary changes with a touch of the cutting wheel and another tack. I wanted the main line of the sub-frame to run parallel to the battery box for visual uniformity. This meant a compromise of seat angle. It is really too steep to be comfortable and this issue is remedied later on with the curved seat pan. The main practical change I made to the sub-frame is a faceted sheet- metal piece that will become the start point of the new &#;tank&#; and double as a mounting point for the controller.
Auxiliary battery
For safety purposes I needed a separate auxiliary battery that would run my lights in the event that the high-voltage system failed or had to be shut off. I used a 4.5Ah SLA (sealed lead acid) battery and made an aluminium cradle for it with mount points allowing it to be bolted inside the frame. The next step was to mount the controller and the rest of the high- voltage components. The controller weighs about 6 kg and has a large aluminium heatsink. It can be run with passive cooling but I wanted the option of liquid cooling if I chose to start playing with performance settings. Initially I set up an aluminium furnace with some old bellows and I tried to cast a plate myself with the path already in it. Then I would just need to pay someone to skim it. I couldn&#;t get a clean pour with such a large shape so I got some 20 mm alloy plate at the metal recyclers and got a coolant path milled in it. Because I had to spot-fill some holes to prepare it, this made it difficult to mill. It is currently just bolted to my controller but later it will be sealed with gasket cement and have coolant forced through it with a simple radiator and pump system.
Using the previously mentioned sub- frame mount point and some frame mount points, I designed a steel framework which supports my controller plate and the other high voltage components including fuse, double pole disconnect, contactor and shunt. I found it quite difficult to t these components in safely and neatly due to space constraints. The emergency disconnect had to be located centrally and forward to allow easy operation in an accident. It is basically a mechanical push switch that requires manual reset. Because it has to hold and break high currents on both poles, it is accordingly large. The high-voltage components between the controller and emergency disconnect are joined electrically with copper bus bars which I found at the metal recyclers and bent and drilled to t. Once these components were in place I heat-formed some 6 mm acrylic to cover the bare terminals and separate these components from the low-voltage components to be mounted above. I think 6 mm was probably too thick, but it allowed me to tap threads for mounting small components. Here I mounted my 12V relays and my six-terminal blade fuse box. I heat formed some 2 mm acrylic mounts to t over the middle of the controller to mount my DC-DC converter. It is rated to drop my pack voltage down to 12V. I adjusted it to 13.7V so it would also charge my SLA auxiliary battery.
Tank
Once all my components were placed I began designing and building a new &#;tank&#; to replace the old tank which was rusted and did not t with the new square-edged aesthetic. I started sketching over photos and then moved to cardboard mock-ups. Next I cut the pieces from 2 mm aluminium, tacking them in place after ensuring mirrored faces were identical. As I went, I drilled and welded suitable mount points.
I knew that during final fitting I would have to cut into the tank and reform some surfaces to accommodate my wiring harness plug and one corner of the controller. I was happy with this as it ts with the boxy, utilitarian theme I was following. Once the tank was fully tacked, I welded it while it was bolted in place. Although my welds are not that pretty, I decided not to grind them back as I didn&#;t want seams cracking in the future. I also like to see welding left if possible, as to me it adds interest to a project. For some parts of the tank I used free software called Pepakura, which allows 3D models to be converted to box nets in order to print and fold paper or card mock ups. The seat pan was made with a similar process to the tank except that I ground all my welds off to improve comfort. It has a temporary foam pad which will be replaced by a thicker seat.
Circuits
Once all the components were placed and major parts fabricated, it was time to wire my high and low-voltage circuits. I drew my own circuit diagram and committed a lot of time in the hope others would find it understandable. I used 50 mm2 cables between motor and controller and also between battery packs. This is sometimes called welding cable and it has an inner and outer sheath. I used a hydraulic crimping tool to crimp terminals onto this thick cable.
To connect individual batteries I used braided copper interconnects. These have some ex in them which may prevent fixing bolts coming loose through vibration. For the low-voltage circuit, I followed my circuit diagram carefully and used heat-shrink for all my connections. The key is to take your time and make sure you have a good range of connectors and wire. I used weatherproof AMPSEAL connectors where components might need to be removed from time to time and where rain might reach.
Headlight
I was initially intent on using an LED headlight on my bike to conserve energy. A good LED headlight will draw around half the current of a halogen bulb and will last longer. There are many cheap options around but reliable e-marked LED units such as Truck-Lite are still out of my price range, although prices are dropping steadily. I opted for a halogen projector light in the end. It is one of the smallest lights available and uses a solenoid to move a curved mirror to switch from low to high beam. I could have mounted my light to either the forks or to the front of the frame. I opted to frame-mount my light as it means that there are fewer wires moving and being stretched as the forks are turned.
I also chose to mount my front indicators near the headlight along with two interfaces; the TBS battery management display and the Curtis display which shows motor RPM, motor temp and more. I used sketches, card models and finally 2 mm aluminium to design a unit to support and protect these parts. I didn&#;t have a hole-saw big enough to cut the holes for the round displays so I had to use a lathe. Its square design has profile lines which match those of the forks.
Thrilling
My first test ride was thrilling to say the least. Having one gear all the way up to the gearing limit of 140km/h and torque available whenever I want it is a feeling that I can&#;t describe. Part of what spurred me on to get the bike rolling was the then-upcoming electric motorsport event called Evolocity, held in Christchurch. I bought a proper key and took the bike to EVolocity, which was an incredibly enjoyable experience. I was able to test my bike against electric bikes on Ruapuna Raceway, as well as see many other amazing electric vehicles on the track and in the pits. My bike came second in the drag event but I was slow on the circuit due to inexperience. Next year I&#;ll put some practice in.
The bike is now very close to being ready for certification. A light is needed to illuminate the number plate, wiring needs to be tidied up and a few cover plates made for exposed components. I am going to use RFID instead of a key to start the bike and this will be done with an Arduino board. The final task will be stripping the bike right down and repainting the frame, sub-frame and wheels. The aluminium parts will be left with their natural finish. I had support and advice from many people during this project but would specifically like to thank Edward Harvey and Iain Jerrett. Also thanks Mum and Dad for letting me use your shed. For questions about the bike please get in touch at [ protected].
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