Building A Bicycle Dropper Seat Post

August 10, 2026 by Fenix Guthrie 4 Comments

A recent addition to mountain bikes is the dropper seat post. This invention is in the vein of office swivel chairs, allowing the seat height to be adjusted with a simple handlebar mounted lever. They are rather fascinating inventions ranging in complexity from simple mechanical systems, to electronic monstrosities actuated by Bluetooth. Inspired by the panoply of possibilities, [kane components] set forth to create such a home-built dropper post.

Inspired by woodworking bar clamps, [kane’s] design utilizing angled plates binding against a rail inside the dropper post. Two pairs of plates sitting at opposite angles resist opposite forces from either the rider sitting on the post, or the return spring. A simple cable actuated cam moves the plates to a nonbinding position when the lever is actuated, and springs return the plates to a binding rest-state. The return is handled by an air spring pressurized against a piston at the bottom of the shaft.

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3D Printing A Usable Airless Tire

August 5, 2026 by Bryan Cockfield 20 Comments

For decades now, companies like Michelin have been teasing us with futuristic-looking automobile tires that don’t use air. Instead, they use a polymer mesh of sorts which maintains the same pressure on the travel surface that a pneumatic tire does, with much less maintenance than their pneumatic counterparts. At least, in theory. There’s a reason that these tires live in the same mythical realm that Half Life 3 and the modern affordable Volkswagen do, and [Berm Peak] decided to discover those reasons for himself.

Of course, [Berm Peak] isn’t building these for his daily driver, an electric pickup truck featured in previous videos of his. He’s putting these on his mountain bike instead, a challenging environment for a tire like this in its own right. When mountain biking at the level he does, punctures and flats can become a real nuisance on the trail, so he set about experimenting with these designs with the 3D printer to see if he could make something rivaling pneumatic technology. After a few design iterations he settled on a TPU-based version with a compliant S-shaped spacing between the tread and wheel. The tire printed in sections that are installed by joining them together on the bike rim with a separate 3D printed rim interface.

At the end of this process [Berm Peak] ends up with a surprisingly capable tire that mostly holds up to his extreme off-road testing, an impressive feat for something 3D printed in his shop. Presumably a company specializing in bicycle tires could build something even more capable, but it turns out that a different technology has already solved all of the problems that airless tires solve. Mountain bikers today almost exclusively ride on tires with sealant, so punctures and flats are essentially a solved problem. But the neon-green airless tires were still a fun project for [Berm Peak] and quite the head-turner out on the bike trails.

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Bike Trainers As Video Game Controllers

August 1, 2026 by Bryan Cockfield 10 Comments

While we’ve largely settled on analog sticks and digital buttons for controlling video games, there’s all sorts of projects to create truly esoteric controllers that allow playing games in unique ways. This one from [sukolupo] lets you use data from standard bike trainers to get your virtual character moving.

Called Deck de France, it maps the data coming from one of the supported bike trainers to a virtual controller which can then be “plugged in” to a Linux system, in this case a Steam Deck mounted to the trainer’s handlebars. Although a bike trainer doesn’t have the same number of inputs as a modern gaming controller, it does have enough to play games like Rocket League. As you might expect, it’s also perfect for biking titles such as the Tour de France series.

As far as unique controllers for video games go, this one is surely up in the rankings with a real trombone or a controller purpose-built for riding virtual horses. It’s also a great way for those who are getting a bit bored of riding their trainers to breathe some new life into their exercise routine. We’ve also seen some open-source alternatives for modern bike trainer software as well, which is another great way to get excited about exercise equipment too.

Use Your Head While Trimming Trees

July 29, 2026 by Bryan Cockfield 42 Comments

[Attoparsec] occasionally rides a bicycle for transportation, but with the major downside of doing this in North America, a place where bicycle infrastructure is generally neglected. From snow removal, maintenance, separation from cars, or even existing in the first place, the places bicyclists use are generally last to be cared for. One of these deficiencies is landscaping maintenance, with plant growth routinely extending into travel ways. Rather than continue to get hit in the face by tree branches, [Attoparsec] took matters into his own hands, or in this case, head.

Since he’s riding down the bike path anyway, the original thought was to add a trimmer to the front of the bicycle. This has a notable downside of being dangerous to others, so instead he added a string trimmer to his helmet. The electric trimmer was scavenged from an old handheld landscaping tool, with a 3D printed mount designed in CAD to cleanly mount to his bicycle helmet. It’s wired to a control on the handlebar, so when a branch is coming up it can be activated by hand and then pruned without much thought other than properly aiming one’s head.

By most measures this eccentric contraption seems to work quite well. There’s not enough torque to affect the rider’s head in any negative way, the strings are long enough to reach far enough to trim the leaves and branches before they can impact the rider’s face, and it’s safe for other users of the bike path. [Attoparsec] calls this “guerrilla urban landscaping”, a bit different from other forms of guerrilla gardening we have seen before.

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Open-Source Mid-Drive E-Bike Motor Has Lots Of Promise, And Hyphens

July 18, 2026 by Tyler August 29 Comments

[Pedro Neves] has a mid-drive e-bike, but he doesn’t own it — not truly, since he can’t repair the motor unit. For a hacker to be in that position, there are only two options: crack the old one and make it your own, or build your own from scratch. [Pedro] built his own and is open-sourcing it on his website for everyone to play with. Right now, that’s .step files and a BOM, so you’ll need to watch the design/build video on YouTube below to get the full picture.

His choice of a motor from an old battery-powered angle grinder is both thrifty and environmentally friendly, so we approve. His goal of 25 km/h seems like a reasonable speed limit, but may still be too fast for some countries’ regulations— so do check the local rules if you’re going to build this. Making the most of 3D-printed components is also a choice that makes the project more accessible, but don’t worry — the bearing surfaces are all metal. That includes the clutch bearing that will let you pedal home if the battery dies or the motor craps out. Well, unless the printed plastic axle gives up the ghost, but that got replaced with a CNC version, so it’s all good. Unless you’ve got legs like Hercules, it ought to hold.

If that’s not DIY enough, you could always build the motor yourself. This mid-drive is also part of a larger project [Pedro] is working on for a whole cargo bike, as he details in his video, which is a worthy project we’ve seen other examples of before.

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Tricking A Bike Counter

June 20, 2026 by Zoe Skyforest 84 Comments

Some municipalities implement bike counters on cycling routes in order to monitor traffic. [nullpxl] recently investigated how these counters work, and explored methods that can be used to trick the counter into thinking a bike passed over it.

A great many of these devices are built using inductive loop sensors. This involves passing a current through a loop of wire embedded in the ground. When a conductive item such as the metal wheel of a bike passes through the electric field, eddy currents are generated in the item, creating their own magnetic field which reacts with the loop’s field itself. This creates a change in inductance which can be measured, and thus used to log the number of times a conductive item has passed over the sensor. By looking at the signature of the inductance change, a system can be tuned to detect specific objects—for example, two bicycle wheels passing over a sensor will create a signal that varies over time in a characteristic way.

[nullpxl] first tried to recreate a “bike” signal for the inductive loop by running over the area holding two metal pans. This wasn’t close enough, so a new idea was needed. Experiments with a scrap bike then indicated that there was a speed gate involved, and that wheeling one wheel over the sensor and back again could trick the sensor into thinking a bike had passed by. Eventually, [nullpxl] distilled all this learning down to create “the BIKE BASKET.” It’s simply a bag with a bike wheel in it, and swinging it over the sensor twice makes the counter tick up.

Is there any money in tricking the average municipal bike counter in your local city? We doubt it, unless Big Bike is getting increasingly filthy in its lobbying efforts. In any case, we love to see weird sensor hacks around these parts. Continue reading “Tricking A Bike Counter” →

Bike-Powered Shredder Makes Short Work Of 3D Printer Waste

June 16, 2026 by Donald Papp 17 Comments

[Brogan M Pratt] and his students do a lot of 3D printing, and as such found themselves producing a lot of plastic waste. Seeing an opportunity, they built a bike-powered plastic shredder that turns a little human exercise into the power needed to transform waste plastic into small bits. Shredding plastic is a necessary first step for any sort of processing, so getting this part working reliably is as important as it is educational.

Shredding is a necessary first step to processing plastic waste.

Being in the Netherlands, using a bike makes perfect sense. But it turns out there’s a lot more to making a human-powered plastic shredder than simply bolting a sprocket to a shredder, looping the bike chain over it, then climbing on and working up a sweat.

In between the bike and the shredder is a large gear reduction, a fifteen kilogram flywheel, and a heavy-duty frame to anchor everything in the face of so much mass and torque. Add some covers and safety guards and the result is a stationary bike with a hopper for waste, a bin for output, and enough rotational torque and inertia to chew through stubborn bits without stalling.

Now that the shredder works, what’s the plan for all the little plastic shreds? The goal is to turn it back into usable filament which is obviously very useful, but we’ve also seen that compression molding plastic waste can work pretty well, too.

Being an educator, [Brogan] makes it clear that a bike-powered shredder, while pretty cool, is not the only missing link in sustainability. There is currently no easy way to recycle plastic at scale. But the shredder is a critical part of demonstrating the whole process in a hands-on way, and learning why recycling plastic at scale is a genuinely difficult job.

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