bicycle

228 Articles

Making The World’s Smallest E-Bike Battery

September 1, 2025 by 25 Comments

Often times, e-bikes seek to build the biggest battery with the most range. But what if you want to take a couple lunch loops on your bike and only need 20 minutes of charge? That’s [Seth] from Berm Peak set out to find out with his minuscule Bermacell battery.

The battery is made from only 14 18650s, this tiny 52V batty is nearly as small an e-bike battery as can be made. Each cell is 3000 mAh making a total battery capacity of 156 Wh. All the cells were welded in series with an off the shelf BMS and everything was neatly packaged in an over-sized 3D printed 9V battery case. [Seth] plans to make another smaller battery with less then 100 Wh of capacity so he can take it on a plane, so stay tuned for more coverage!

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A photo of a Stirling Engine attached to a bike

Building A Stirling Engine Bike

July 17, 2025 by 27 Comments

Over on his YouTube channel [Tom Stanton] shows us how to build a Stirling Engine for a bike.

A Stirling Engine is a heat engine, powered by the expansion and contraction of a working fluid (such as air) which is heated and cooled in a cycle. In the video [Tom] begins by demonstrating the Stirling Engine with some model engines and explains the role of the displacer piston. His target power output for his bike engine is 150 watts (about 0.2 horsepower) which is enough power to cycle at about 15 mph (about 24 km/h). After considering a CPU heatsink as the cooling system he decided on water cooling instead.

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A man is shown performing a wheelie on a red bicycle in a classroom. In the background, a projector is displaying a phone screen running an indistinct app.

An Adaptive Soundtrack For Bike Tricks

June 22, 2025 by 7 Comments

If you’ve put in all the necessary practice to learn bike tricks, you’d probably like an appropriately dramatic soundtrack to accompany your stunts. A team of students working on a capstone project at the University of Washington took this natural desire a step further with the Music Bike, a system that generates adaptive music in response to the bike’s motion.

The Music Bike has a set of sensors controlled by an ESP32-S3 mounted beneath the bike seat. The ESP32 transmits the data it collects over BLE to an Android app, which in turn uses the FMOD Studio adaptive sound engine to generate the music played. An MPU9250 IMU collects most position and motion data, supplemented by a hall effect sensor which tracks wheel speed and direction of rotation.

When the Android app receives sensor data, it performs some processing to detect the bike’s actions, then uses these to control FMOD’s output. The students tried using machine learning to detect bike tricks, but had trouble with latency and accuracy, so they switched to a threshold classifier. They were eventually able to detect jumps, 180-degree spins, forward and reverse motion, and wheelies. FMOD uses this information to modify music pitch, alter instrument layering, and change the track. The students gave an impressive in-class demonstration of the system in the video below (the demonstration begins at 4:30).

Surprisingly enough, this isn’t the first music-producing bike we’ve featured here. We’ve also seen a music-reactive bike lighting system.

Thanks to [Blake Hannaford] for the tip!

Automatic Transmission For Manual Transportation

May 15, 2025 by 31 Comments

The drivetrain of most modern bicycles has remained relatively unchanged for nearly a century. There have been marginal upgrades here and there like electronic shifting but you’ll still mostly see a chain with a derailleur or two. [Matthew] is taking a swing at a major upgrade to this system by replacing the front derailleur with a torque converter, essentially adding an automatic transmission to his bicycle.

Most of us will come across a torque converter in passenger vehicles with automatic transmissions, but these use fluid coupling. [Matthew] has come up with a clever design that uses mechanical coupling instead using a ratchet and pawl mechanism. There are two gear ratios here, a 1:1 ratio like a normal bicycle crank and a 1.5:1 ratio that is automatically engaged if enough torque is applied to the pedals. This means that if a cyclist encounters a hill, the gear automatically shifts down to an easier gear and then will shift back once the strenuous section is finished.

[Matthew] machined all the parts for this build from scratch, and the heavy-duty solid metal parts are both impressive but also show why drivetrains like this haven’t caught on in the larger bicycling world since they’re so heavy. There have been some upgrades in internally geared hubs lately though, which do have a number advantages over traditional chain and derailleur-based bikes with the notable downside of high cost, and there have been some other interesting developments as well like this folding mechanical drivetrain and this all-electric one.

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A Bicycle Is Abandonware Now? Clever Hack Rescues Dead Light

April 24, 2025 by 75 Comments

A bicycle is perhaps one of the most repairable pieces of equipment one can own — no matter what’s wrong with it, and wherever you are on the planet, you’ll be able to find somebody to fix your bike without too much trouble. Unfortunately as electric bikes become more popular, predatory manufacturers are doing everything they can to turn a bike into a closed machine, only serviceable by them.

That’s bad enough, but it’s even worse if the company happens to go under. As an example, [Fransisco] has a bike built by a company that has since gone bankrupt. He doesn’t name them, but it looks like a VanMoof to us. The bike features a light built into the front of the top tube of the frame, which if you can believe it, can only be operated by the company’s (now nonfunctional) cloud-based app.

The hack is relatively straightforward. The panel for the VanMoof electronics is removed and the works underneath are slid up the tube, leaving the connector to the front light. An off the shelf USB-C Li-Po charger and a small cell take the place of the original parts under a new 3D printed panel with a switch to run the light via a suitable resistor. If it wasn’t for the startling green color of the filament he used, you might not even know it wasn’t original.

We would advise anyone who will listen, that hardware which relies on an app and a cloud service should be avoided at all costs. We know most Hackaday readers will be on the same page as us on this one, but perhaps it’s time for a cycling manifesto to match our automotive one.

Thanks [cheetah_henry] for the tip.

A New Kind Of Bike Valve?

April 15, 2025 by 52 Comments

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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Bicycle Adds Reliability With Second Chain

February 3, 2025 by 70 Comments

Ignoring the International Cycling Union‘s mostly arbitrary rules for what a bicycle is “supposed” to look like (at least if you want to race), there are actually reasons that the bicycling world has standardized around a few common parts and designs. Especially regarding the drivetrain, almost all bikes use a chain, a freewheel, and a derailleur if there are gears to shift because these parts are cheap, reliable, and easy to repair. But if you’re off grid in a place like Africa, even the most reliable bikes won’t quite cut it. That’s why a group called World Bicycle Relief designed and built the Buffalo bicycle, and the latest adds a second gear with a unique freewheel.

Bicycling YouTuber [Berm Peak] takes us through the design of this bike in his latest video which is also linked below. The original Buffalo bicycle was extremely rugged and durable, with a rear rack designed to carry up to 200 pounds and everything on the bike able to be repaired with little more than an adjustable wrench. The new freewheel adds a second gear to the bike which makes it easier to use it in hilly terrain, but rather than add a complicated and hard-to-repair derailleur the freewheel adds a second chain instead, and the rider can shift between the two gears by pedaling backwards slightly and then re-engaging the pedals.

Of course a few compromises had to be made here. While the new freewheel is nearly as rugged as the old one, it’s slightly more complex. However, they can be changed quite easily with simple tools and are small, affordable, and easy to ship as well. The bike also had to abandon the original coaster brake, but the new rim brakes are a style that are also easy to repair and also meant that the bike got a wheel upgrade as well. Bicycles like these are incredibly important in places where cars are rare or unaffordable, or where large infrastructure needed to support them is unreliable or nonexistent. We’ve seen other examples of bicycles like these being put to work in places like India as well.

Thanks to [Keith] for the tip!

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