Bicycle Gearbox Does It By Folding

If you’ve spent any time on two wheels, you’ve certainly experienced the woes of poor bicycle shifting. You hit the button or twist the knob expecting a smooth transition into the next gear, only to be met with angry metallic clanking that you try to push though but ultimately can’t. Bicycle manufacturers collectively spent millions attempting to remedy this issue with the likes of gearboxes, electronic shifting, and even belt-driven bikes. But Praxis believes to have a better solution in their prototype HiT system.

Rather then moving a chain between gears, their novel solution works by folding gears into or away from a chain. These gears are made up of four separate segments that individually pivot around an axle near the cog’s center. These segments are carefully timed to ensure there is no interference with the chain making shifting look like a complex mechanical ballet.

While the shift initialization is handled electronically, the gear folding synchronization is mechanical. The combination of electronic and mechanical systems brings near-instant shifting under load at rotational rates of 100 RPM. Make sure to scroll through the product page and watch the videos showcasing the mechanism!

The HiT gearbox is a strange hybrid between a derailleur and a gearbox. It doesn’t contain a clutch based gear change system or even a CVT as seen in the famous Honda bike of old. It’s fully sealed with more robust chains and no moving chainline as in a derailleur system. The prototype is configurable between four or sixteen speeds, with the four speed consisting of two folding gear pairs connected with a chain and the sixteen speed featuring a separate pair of folding gears. The output is either concentric to the input, or above the input for certain types of mountain bikes.

Despite the high level of polish, this remains a prototype and we eagerly await what Praxis does next with the system. In the meantime, make sure to check out this chainless e-drive bicycle.

A New Kind Of Bike Valve?

If you’ve worked on a high-end mountain or road bike for any length of time, you have likely cursed the Presta valve. This humble century-old invention is the bane of many a home and professional mechanic. What if there is a better option? [Seth] decided to find out by putting four valves on a single rim.

The contenders include the aforementioned Presta, as well as Schrader, Dunlop and the young gun, Clik. Schrader and Dunlop both pre-date Presta, with Schrader finding prevalence in cruiser bicycles along with cars and even aircraft. Dunlop is still found on bicycles in parts of Asia and Europe. Then came along Presta some time around 1893, and was designed to hold higher pressures and be lower profile then Schrader and Dunlop. It found prevalence among the weight conscious and narrow rimmed road bike world and, for better or worse, stuck around ever since.

But there’s a new contender from industry legend Schwalbe called Clik. Clik comes with a wealth of nifty modern engineering tricks including its party piece, and namesake, of a clicking mechanical locking system, no lever, no screw attachment. Clik also fits into a Presta valve core and works on most Presta pumps. Yet, it remains to be seen whether Clik is just another doomed standard, or the solution to many a cyclists greatest headache.

This isn’t the first time we’ve seen clever engineering going into a bike valve.

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A Self Balancing Bike For Crash Dummy Billy

We aren’t sure there’s enough information in the [We Make Machines’] video to easily copy their self-balancing bike project, but if you want to do something similar, you can learn a lot from watching the video. Building sufficient gyros to keep the bike stable required quite a bit of trial and error.

There are some tricks to getting a stable heavy weight to rotate without a lot of vibration and problems. The gyros go on the rider’s saddle, so you aren’t going to be able to ride in the normal fashion. However, a substantial motor drives the wheels so there’s no need to pedal.

The first attempt to self-balance stayed stable for about 10 seconds. Some of it was fine-tuning code, but noise from the gyros also threw off the angle sensor. A higher-quality sensor seemed promising, but it didn’t really fix the problem. Instead of using PID, the guys tried an LQR (Linear Quadratic Regulator) algorithm. Once that was sorted and a servo allowed for steering, it was time to let the bike roam free.

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Electric Bike Uses No Electronics, Weird Motor

E-bikes combine a bicycle with a big lithium battery, a speed controller, and a motor. What you get from that combination is simple, efficient transportation. [Tom Stanton] wanted to build an e-bike himself, but he did it without any of the fancy electronic components. But the real gem? The weird janky motor he built to run it.

The concept is simple. An e-bike is electric, in that it has an electric motor and a source of electric power. However, [Tom] intended to eliminate the electronic parts—the speed controller, any battery balancing hardware, and the like. Just think no transistors and microchips and you’ve got the right idea. Basically, [Tom] just built an e-bike with motor weak enough that it doesn’t need any fancy throttle control. He can just turn the motor hard on or off with a switch.

The bike is built around a reed switch motor. This uses magnets on a rotor, which interact with a reed switch to time pulses of electricity to coils which drive the motor. [Tom] wound the coils and built the motor from scratch using 3D printed components. The project quickly ran into problems as the reed switch began to suffer degradation from arcing, which [Tom] solved with some innovative tungsten contacts.

Controlling the bike is pretty simple—there’s just a switch connecting a capacitor bank to the motor to provide power on command. No electronics! However, [Tom] has also neatly set up the motor to charge a bank of supercapacitors when coasting downhill. In this regard, the bike can store power on a descent and then use it for a boost when required later on. Between the weird motor and the weedy capacitor bank, it doesn’t do much, but it does work.

If he’s looking for a more potent power source, perhaps the answer is already out on the street — in the form of a battery pack salvaged from the cells in discarded vapes.
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Front view of blue bicycle with Raspberry Pi webserver

Pedaling Your Mobile Web Server Across The Globe

We tinkerers often have ideas we know are crazy, and we make them up in the most bizarre places, too. For example, just imagine hosting a website while pedaling across the world—who would (not) want that? Meet [Jelle Reith], a tinkerer on an epic cycling adventure, whose bicycle doubles as a mobile web server. [Jelle]’s project, jelle.bike, will from the 6th of December on showcase what he’s seeing in real time, powered by ingenuity and his hub dynamo. If you read this far, you’ll probably guess: this hack is done by a Dutchman. You couldn’t be more right.

At the heart of [Jelle]’s setup is a Raspberry Pi 4 in a watertight enclosure. The tiny powerhouse runs off energy generated by a Forumslader V3, a clever AC-to-DC converter optimized for bike dynamos. The Pi gets internet access via [Jelle]’s phone hotspot, but hosting a site over cellular networks isn’t as simple as it sounds. With no static IP available, [Jelle] routes web traffic through a VPS using an SSH tunnel. This crafty solution—expanded upon by Jeff Geerling—ensures seamless access to the site, even overcoming IPv6 quirks.

The system’s efficiency and modularity exemplify maker spirit: harnessing everyday tools to achieve the extraordinary. For more details, including a parts list and schematics, check out [Jelle]’s Hackaday.io project page.

BikeBeamer Adds POV Display To Bicycle Wheels

Unless you’re living in a bicycle paradise like the Netherlands, most people will choose to add some sort of illumination to their bicycle to help drivers take note that there’s something other than a car using the road. Generally, simple flashing LEDs for both the front and the rear is a pretty good start, but it doesn’t hurt to add a few more lights to the bicycle or increase their brightness. On the other hand, if you want to add some style to your bicycle lighting system then this persistence of vision (POV) display called the BikeBeamer from [locxter] might be just the thing.

The display uses four LED strips, each housed in their own 3D printed case which are installed at 90-degree angles from one another in between the spokes of a standard bicycle wheel. An ESP32 sits at the base of one of the strips and is responsible for storing the image and directing the four displays. This is a little more complex than a standard POV display as it’s also capable of keeping up with the changing rotational speeds of the bicycle wheels when in use. The design also incorporates batteries so that no wires need to route from the bike frame to the spinning wheels.

This is an ongoing project for [locxter] as well, meaning that there are some planned upgrades even to this model that should be in the pipe for the future. Improving the efficiency of the code will hopefully allow for more complex images and even animations to be displayed in the future, and there are also some plans to improve the PCB as well with all surface-mount components. There are a few other ways to upgrade your bike’s lighting as well, and we could recommend this heads-up headlight display to get started.

Two pieces of paper on a table with a pair of pliers, a screwdriver, and a cup of what is probably coffee or tea. The sheets show a diagram of a bicycle handlebar on one side with a labeled "controller box, controller lever, mount, and battery." The other sheet shows a side view of a 150kg servo mounted on a plate that runs over to a brake caliper with a battery, receiver, and power stabilizer. These parts are also labeled in red text.

Wireless Bike Brakes

Bicycles are the most efficient machines for moving a person around, and wireless drivetrains have been heralded as a way to make shifting more consistent and require less maintenance. [Blake Samson] wondered if the same could be true of wireless brakes.

A closeup of a bike front fork with a large 150kg servo mounted to a plate that puts it above the disc brake caliper. To the side of the caliper, wires are visible going between the servo, control box, and battery.Inspired by the controller for an RC car, [Blake] picked a 150 kg servo attached to a cable-actuated hydraulic disc caliper to apply the braking force. The servo, receiver, power stabilizer, and batteries were all mounted on a custom steel plate fabricated to mount under the caliper. [Blake] cut up an old set of mountain bike brake levers to reuse the handlebar mounts and then put the batteries, controller, and finger triggers on them.

Confident in his hacking skills, [Blake] then took the bike out on some trails to test the brakes. As a prototype, there were a few surprises along the way, like one of the triggers staying locked in the braking position, but they performed admirably enough that he’s mulling over a Mk. 2.

Bikes are one of our favorite hacking platforms. Be sure to checkout this dreamy cargo bike build, an awesome bike camper, or what can happen if your bike is dependent on the cloud to work.

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