Electric bikes have increased in popularity dramatically over the past few years, and while you can easily buy one from a reputable bicycle manufacturer, most of us around here might be inclined to at least buy a kit and strap it to a bike we already have. There aren’t kits available for every bike geometry, though, so if you want an electric BMX bike you might want to try out something custom like [Shea Nyquist] did with his latest build. (Video, embedded below.)
BMX frames have a smaller front triangle than most bikes, so his build needed to be extremely compact. To that end, it uses two small-sized motors connected together with a belt, which together power a friction drive which clamps against the rear tire to spin it directly. This keeps the weight distribution of the bike more balanced as well when compared to a hub drive, where the motor is installed in the rear wheel. It also uses a more compact lithium polymer battery pack instead of the typical 18650 lithium ion packs most e-bikes use, and although it only has a range of around three miles it’s more than enough charge to propel it around a skate park.
Electric bikes, and really all electric vehicles, have one major downside: the weight and cost of batteries. Even with lithium, battery packs for ebikes can easily weigh more than the bike itself and cost almost as much. But having to deal with this shortcoming could be a thing of the past thanks to [LightningOnDemand]’s recent creation. Of course, this would rely on a vast infrastructure of Tesla coils since that’s how this bike receives the power it needs to run its electric motor.
The Tesla coil used for the demonstration is no slouch, either. It’s part of the Nevada Lightning Laboratory and can pack a serious punch (PDF warning). To receive the electrical energy from the coil, the bike (actually a tricycle) uses a metal “umbrella” of sorts which then sends the energy to the electric motor. The bike drags a chain behind itself in order to have a ground point for the electricity to complete its circuit. There is limited range, though, and the Tesla coil will start ionizing paths to the ground if the bike travels too far away.
While we can’t realistically expect Tesla’s idea of worldwide, free, wireless electricity to power our bicycles anytime soon, it is interesting to see his work proven out, even if its on a small scale like this. Of course, it doesn’t take a research laboratory to start working with Tesla coils. This one is built out of common household parts and still gets the voltages required to create the signature effects of a Tesla coil.
The drive train of this bicycle starts with a brushless DC motor from a washing machine. It has been slightly modified to run on 48 volts, and is installed inside the triangle of the bike’s frame. It has a chain driving the bike’s crank, retaining the original chain and gearing setup (unlike many electric bike hacks that utilize hub motors). The crank has also been specially modified to include a freewheel, a necessary feature so that the motor can operate without spinning the pedals. Everything except the motor has been custom fabricated including the mounts and the electronics.
[jimminecraftguy] reports speeds of 110 kph which is a little crazy for a 20-year-old aluminum frame bike, and we’d guess it’s not street legal in many jurisdictions, but we can’t really find much fault with this build in general based on the amount of innovation required to get this working at all. A few more improvements for the build are in the works, including improved batteries and a cover for the sides to keep the local law enforcement from getting too suspicious. We can’t wait to see the final version. Continue reading “The Spin Cycle: Washing Machine Motor Converts 10-Speed To E-Bike”→
While it’s nice to be able to fully restore something vintage to its original glory, this is not always possible. There might not be replacement parts available, the economics of restoring it may not make sense, or the damage to parts of it might be too severe. [onyxmember] aka [Minimember Customs] was in this position with an old ’54 Puch Allstate motorcycle frame that he found with no engine, rusty fuel tank, and some other problems, so he did the next best thing to a full restoration. He converted it to electric.
This build uses as much of the original motorcycle frame as possible and [onyxmember] made the choice not to weld anything extra to it. The fuel tank was cut open and as much rust was cleaned from it as possible to make room for the motor controller and other electronics. A hub motor was laced to the rear wheel, and a modern horn and headlight were retrofitted into the original headlight casing. Besides the switches, throttle, and voltmeter, everything else looks original except, of course, the enormous 72V battery hanging off the frame where the engine used to be.
At a power consumption of somewhere between three and five kilowatts, [onyxmember] reports that this bike likely gets somewhere in the range of 55 mph, although he can’t know for sure because it doesn’t have a speedometer. It’s the best use of an old motorcycle frame we can think of, and we also like the ratrod look, but you don’t necessarily need to modify a classic bike for this. A regular dirt bike frame will do just fine.
There’s no better way of improving a project than logging data to make informed decisions on future improvements. When it came to [Brian]’s latest project, an electric bike, he wanted to get as much data as he could from the time he turned it on until the time he was finished riding. He turned to a custom pyBoard-based device (and wrote it up on Hackaday.io), but made it stackable in order to get as much information from his bike as possible.
This isn’t so much an ebike project as it is about a microcontroller platform that can be used as a general purpose device. All of the bike’s controls flow through this device as a logic layer, so everything that can possibly be logged is logged, including the status of the motor and battery at any given moment. This could be used for virtually any project, and the modular nature means that you could scale it up or down based on your specific needs. The device is based on an ARM microcontroller so it has plenty of power, too.
In the ebike world, there are two paths. The first is a homemade kit bike with motors and controllers from China. The second is a prebuilt bike from a manufacturer like Giant, with motors and controllers from China, which will be half as fast and cost three times as much. The choice is obvious, and there are other benefits to taking the first path as well, such as using this equipment which now has an open source firmware option.
The Tong Sheng TSDZ2 drive is popular in the ebike world because it’s an affordable kit motor which has a pedal-assist mode using torque sensors, resulting in a more polished experience. In contrast, other popular kit motors tend to rely on less expensive cadence sensors which are not as smooth or intuitive. This new open source firmware for the TSDZ2 further improves on the ride by improving the motor responsiveness, improving battery efficiency, and opening up the ability to use any of a number of color displays. (More information is available on a separate Wiki.)
If you have a TSDZ2-based ebike it might be time to break out the laptop and get to work installing this firmware. If you’re behind the times and still haven’t figured out that ebikes are one of the best ways to travel, here is the proof you need.
Thanks to [coaxial] for the tip! Photo via Reddit user [PippyLongSausage].
[Tom Stanton] is well-regarded in the maker community, and has put much effort in over the years on a variety of electric vehicle builds. In the process of upgrading his e-bike last year, he ran into some issues with the main drive pulley. Rather than rely on guesswork, he threw engineering at the problem.
The problem concerned the mounting bolts on the pulley’s hub, which would pull out under high torque. [Tom’s] initial finite element simulations had suggested the design was sound, but reality was proving otherwise. After further analysis and testing, [Tom] determined that his analysis hadn’t properly simulated the bolt pull-out condition. With this corrected in the software, it was readily apparent that there simply wasn’t enough material around the bolt holes to hold the torque load.
With the simulation now more closely agreeing with reality, [Tom] was able to correct the design. New parts were created with a strengthened mounting section, and the pulley was successfully able to deal with the loads in service.
It’s a great example of using engineering simulation tools to solve a problem quickly, rather than simply guessing and hoping things will hold up. We’ve seen [Tom]’s work before, too — like this fun backyard trebuchet build. Video after the break.