How Does a Bike Stay Upright?


If you give a bike a good push down a hill, it can ride off into the sunset without you. Moving bikes can stay upright even without a rider. Why is this? 

The folks at MinutePhysics take a look at the phenomenon: 

When a moving bike begins tilting to one side, it also automatically steers in that direction, bringing it back into balance. There are several reasons for this, physically speaking, all of which come together to help keep a bike upright:

Bikes have a steering axis that’s tilted slightly backward, toward the seat. The bike wheel makes contact with the ground slightly behind that axis, so when the bike turns, the upward force of the ground turns the wheel and handlebars in the same direction. 

The weight of the handlebars is positioned slightly in front of the steering axis. When the bike turns, the downward pull from the mass of the handlebars helps turn the wheel in the same direction. 

Gyroscopic precession, which governs how helicopters steer, also affects bikes. When a force is applied to a spinning wheel, the movement happens 90 degrees beyond where it was applied. So force applied pushing the bike left from the ground actually turns the middle of the wheel left.

The reason a slow-moving bike doesn’t stand up is that the wheel doesn’t have enough time to turn to keep the bike in balance. 

So, maybe don't push your bike down a big hill. 

[h/t: NPR

All images from MinutePhysics // Screenshots via YouTube

George Barratt-Jones, Vimeo
This Crafty Bicycle Can Knit a Scarf in 5 Minutes
George Barratt-Jones, Vimeo
George Barratt-Jones, Vimeo

Knitting can be a time-consuming, meticulous task, but it doesn’t need to be. At least not if you’re George Barratt-Jones. As The Morning News spotted, the Dutch designer recently created a human-powered automated knitting machine that can make a scarf while you wait for your train to arrive.

The Cyclo-Knitter is essentially a bicycle-powered loom. As you pedal a stationary bike, the spinning front wheel powers a knitting machine placed on top of a wooden tower. The freshly knitted fabric descends from the top of the tower as the machine works, lowering your brand-new scarf.

Cyclo Knitter by George Barratt-Jones from George Barratt-Jones on Vimeo.

“Imagine it’s the midst of winter,” Barratt-Jones, who founded an online skill-sharing platform called Kraftz, writes of the product on Imgur. “You are cold and bored waiting for your train at the station. This pedal powered machine gets you warm by moving, you are making something while you wait, and in the end, you are left with a free scarf!”

Seems like a pretty good use of your commute down-time, right?

If you're a fan of more traditional knitting methods, check out these knitting projects that can put your needles to work, no bicycle required.

[h/t The Morning News]

Netherlands Officials Want to Pay Residents to Bike to Work

Thinking about relocating to the Netherlands? You might also want to bring a bike. Government officials are looking to compensate residents for helping solve their traffic congestion problem and they want businesses to pay residents to bike to work, as The Independent reports.

Owing to automobile logjams on roadways that keep drivers stuck in their cars and cost the economy billions of euros annually, Dutch deputy infrastructure minister Stientje van Veldhoven recently told media that she's endorsing a program that would pay employees 19 cents for every kilometer (0.6 miles) they bike to work.

That doesn't sound like very much, but perhaps citizens who need to trek several miles each way would appreciate the cumulative boost in their weekly paychecks. For employers, the benefit would be a healthier workforce that might take fewer sick days and reduce parking needs.

Veldhoven says she also plans on designing a program that would assist employers in supplying workers with bicycles. The goal is to have 200,000 people opting for manual transportation over cars. If the program proceeds, it might find a receptive population. The Netherlands is already home to 22.5 million bikes, more than the 17.1 million people living there. In Amsterdam, a quarter of residents bike to work.

There's no timeline for implementing the pay-to-bike plan, but early trial studies indicate that the expense might not have to be a long-term prospect. Study subjects continued to bike to work even after the financial rewards stopped.

[h/t The Independent]


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