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.

SpaceMouse Destroyed For Science

The SpaceMouse is an interesting gadget beloved by engineers and artists alike. They function almost like joysticks, but with six degrees of freedom (6DoF). This can make them feel a bit like magic, which is why [Thought Bomb Design] decided to tear one apart and figure out how it works.

The movement mechanism ended up being relatively simple; three springs soldered between two PCBs with one PCB being fixed to the base and the other moving in space. Instead of using a potentiometer or even hall effect sensor as you might expect from a joystick, the space mouse contained a set of six LEDs and light meters.

The sensing array came nestled inside a dark box made of PCBs. An injection molded plastic piece with slits would move to interrupt the light coming from the LEDs. The mouse uses the varying values coming from the light meter to decode Cartesian motion of the space mouse. It’s very simple and a bit hacky, just how we like it.

Looking for a similar input device, but want to take the DIY route? We’ve seen a few homebrew versions of this concept that might provide you with the necessary inspiration.

Continue reading “SpaceMouse Destroyed For Science”

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.

Continue reading “A New Kind Of Bike Valve?”