Archive for the ‘Balance’ Category

Higher education on two wheels

27/04/2015

If you’ve not heard of the Faculty of Science and Engineering at the University of Chester, you have now. It’s new, fast-moving and extremely welcoming.

What’s it got to do with cycling science? Well, the powers that be at the Faculty have their fingers on the pulse and recognise that cycling is blossoming.

So they invited me to lead a cycling science ride at the weekend, an initiative generously supported by CWAC/iTravel.Under the railway bridge

That’s why a group of people could be found in a back lane near the River Dee, discussing the functions, materials and dimensions of that most under-rated component, the spoke.

Tangential, radial, three-cross, four-cross, bladed, steel, aluminium, carbon – all the little niceties were discussed vigorously.

One of the cyclists realised for the first time that the front wheel he’d been using for more than a year has lovely radial spokes – and why his rear wheel doesn’t.

To cap it all, another rider, an information systems expert of course, had a tuning app on her smartphone so we could demonstrate to any doubters that it’s the tension in the wire spoke that keeps the wheel together.

Fact: knowledge keeps the legs warm

Fact: knowledge keeps the legs warm

The weight of a general practitioner, who volunteered innocently, bearing down on the axle was then shown to be enough to reduce the frequency of the lowermost spoke by half a tone.

Elsewhere on the ride, along Chester’s glorious Greenway, the effects of rolling resistance were demonstrated by putting some air in the tyres on which an esteemed chemical engineer usually rides almost totally flat.

Human balance, steering, the self-stable dynamics of a bicycle, aerodynamics and how to hover simply by pedalling hard (and building an enormous lightweight helicopter) were all covered.

So, if you’re looking to study science or engineering, you could do worse than to consider Chester University. Not only do they know HOW a bicycle works, they also know WHY.

Photos: Garfield Southall

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Anti-Gravity Cycling

16/03/2014

Why does a moving bicycle stay upright? It seems a simple question but, as yet, nobody has been able to answer it exactly.

Scientists are getting closer but mystery still surrounds the precise way geometry, mass, gravity, velocity and gyroscopic forces combine to keep an articulated two-wheeler coasting along, even when there’s no rider.

Now one expert of bike stability, Professor Andy Ruina of Cornell University in Ithaca, New York, has been discussing a curious finding that adds a little more to our knowledge. Last year he presented it to a quiet meeting in Japan. This month he repeated it in the US. If you weren’t at either, here’s the gist.

First, his students built a tricycle, with one wheel at the front and three at the back.Bricycle static

Like most tricycles, the front wheel steers. Unlike most tricycles, there is an adjustable suspension spring for the rear set of wheels.

It’s not a suspension spring to absorb vibration. Instead, it can be adjusted to allow the tricycle’s rear wheels to lean into the corner, in the same way that the rear wheel of a bicycle leans in.

Pushing the bricycleWhen the suspension spring is given complete flexibility, the rear wheels tilt as the rider leans into the corner, exactly like a bicycle.

When the suspension is locked to rigid, the rear wheels are locked upright and the tricycle corners exactly like a tricycle.

That’s why Ruina has nicknamed this hybrid machine as a “bricycle” (not to be confused with the energetic Bricycles cycling pressure group in Brighton UK).

The weirdest thing happens, though, when the suspension is adjusted somewhere in between being being totally flexible and being locked rigid, at a critical point where it counterbalances the forces created for steering.

Leaning in anti-gravity

Suspension adjusted to eliminate the effect of gravity

At this setting, the suspension eliminates the effects of gravity.

It becomes an anti-gravity bricycle.

When the bricyclist tries to corner, by turning the front wheel and/or leaning towards the centre of the curve, the bricycle does not respond. It will not change direction. It just keeps on going straight on.

So, by switching off gravity, it’s impossible to alter course.

What does this clever experiment reveal?

Well, now we know that, as cyclists, without gravity we would be fated to riding forever in one direction. If we wanted to change course we’d have to stop, dismount, pick up our bicycle, turn it and start off again. Our bicycle would be as manoeuverable as a train that’s gone off the rails.

We may curse gravity when we’re riding uphill but, from now on, we should give gravity due praise every time we steer.

*I first stumbled across an abstract of Professor Ruina’s paper and tweeted it in January 2014, later that month he kindly engaged in a Skype conversation. Since then, he and his team have posted an explanatory video of the bricycle in action, with a full explanation of the physics at work. It’s well worth watching – several times!

"Shall we just cycle home?"

“Shall we just cycle home?”