Back here I covered how, when I first started to design my Air 150 recumbent trike , I spent a lot of time looking for the lightest possible springs.

I tried rubber springs (in torsion, shear and compression), carbon fibre, elastomers and others.

My initial desire was to use torsion bars, preferably made from spring steel. However, I gave up on doing this for a number of reasons – weight, stress level in the steel (best addressed by using multiple leaves, Volkswagen Beetle style), and the difficulty in fastening the ends of the bar without introducing even higher stresses.

And the Firestone air-springs I chose to use in the final design are still my pick for springs in ultra light-weight vehicles.

But the other day I came across a product that might have changed the situation. It’s a type of skateboard that uses two wheels, mounted in line. The two halves of the board can pivot relative to one another around a longitudinal axis, and the two wheels can rotate, castor style.

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The other day I was reading a very interesting book. ‘Behind the Wheel’ is a social history of motoring (as opposed to a history of cars). It was first published in 1977 and was authored by Maurice Michael and Lord Montagu of Beaulieu. Here is one section I found fascinating:

Imagine the modern motorist’s reactions to being placed in the driving seat of, say, an 1898 Benz.

”It’s very comfortable sitting up here and the visibility is splendid, but there isn’t any instrument panel. Where do I find the starter switch?”

”There is no starter switch; the electric starter has not yet been invented.”

”I suppose we start by hand, then. Where’s the starting handle?”

“There’s no starting handle either. You simply turn the engine over by pulling on the rim of the flywheel, and hope for better luck than the famous Mr. Koosen who wrote that he had done so ‘… until darkness overtook me. The only result was a pair of worn-out gloves.’ Oh and do retard the ignition first with that push-pull knob behind your legs. There isn’t any crankcase, and if the engine should back-fire you don’t want to catch your hand in the flywheel. Where is the engine, did you say? It’s underneath your seat.”

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Suspension design is great fun, and very challenging.

I am not talking about ‘design’ as in picking which upgrade kit to buy for your car, but much more fundamental aspects like developing a whole new suspension – anti-dive percentage, camber change, longitudinal and lateral virtual swing arm lengths… stuff like that.

I haven’t done it for a car but I have applied exactly the same concepts to human powered vehicles.

When I designed the double wishbone front end for my first recumbent trike, I struggled with setting the ground rules. Like the:

• Position of front upper wishbone mount
• Position of rear upper wishbone mount
• Position of front lower wishbone mount
• Position of rear lower wishbone mount
• Position of upper ball-joint
• Position of lower ball-joint

With each location defined in three planes, that’s 18 variables. Add to that wheel offset and diameter, and inner and outer steering tie rod positions, and you’re looking at 26 or more accurate dimensions needed before you can even start.

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In my hand right now I am holding a bolt.

More specifically, it’s an Allen-key bolt (sometimes called a ‘cap screw’) that’s 30mm long and 10mm in diameter. It uses a metric thread.

It’s a high tensile bolt, which means – in plain terms – that it’s bloody strong.

I’ve just stepped over to the digital scales – it weighs 28 grams.

Now the reason that the bolt was sitting on my desk is that a moment or two ago I took it out of my pocket. And the reason it was in my pocket is that I’ve just stepped in from my home workshop, after finishing for the evening.

I’ve been building ‘Chalky’, my recumbent, full suspension touring bike that I hope to be one of the best human-powered touring machines in the world. Best for me, anyway.

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Hastened by the current world financial crisis and its effects on (particularly) US car makers, there is growing discussion in this country about the demise of the Ford Falcon model.

What to many people was unthinkable even only a year or two ago is now becoming an ‘it’ll probably happen’ scenario that while not palatable, is at least open for discussion.

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The boom in GPS-based navigation systems must have seen a diminution in sales of book-based street directories. I haven’t seen the figures to support that, but it’s certainly what you’d assume to be taking place.

But the companies that produce street directories (and of course in many cases also supply the software for the nav systems) are fighting back.

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As I have said in the past, AutoSpeed’s internal data generates a daily referrers’ list, where I can see discussion groups and other web pages from which readers are coming.

I read the referrers’ list (and then follow many links) at least a couple of times a day. It tells me, indirectly, which are our most popular articles for that day, and even more importantly, it also shows me how well each article is understood.

Huh – ‘how well it is understood’?

Well, the sad truth is that many AutoSpeed articles are completely misunderstood by readers. But again, that’s useful to me – if my writing hasn’t been clear enough, or the photos of sufficient quality, then I get to see the outcome expressed loud and clear.

But there’s nothing I can do about wilful ignorance.

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The other day I made a purchase that can only be considered an amazing bargain.

I first saw the goods (and then bought them) on Australian eBay, but by going direct to the manufacturer’s site, you can get them even cheaper.

So what am I talking about? Hose clamps – no less than 150 of them!

For just AUD$64.90 you get 150 stainless steel hose clamps to suit hoses from 6mm to 60mm. The clamps are packaged in boxes and appear to be of good quality.

And not only that, but you also get a flexible drive screwdriver (complete with three different sized socket bits to suit the clamps), a travel mug and a carry bag!

The company claims the retail value to be $240 – and that sounds about right.

The $64.90 cost includes postage to anywhere in Australia, and mine came delivered in a good quality cardboard box.

The deal is ‘while stocks last’ so you’d better get in fast!

Go here for the details.

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Over the years I have built plenty of simple structures that I’ve wanted to be both light and strong.

Those structures vary from little brackets that might be holding something in the engine bay, to complete human-powered vehicles that I trust my life to.

In all cases, the starting point for the design is to consider the forces involved. How does the force of gravity act on the structure? What direction do braking loads act in, or short-term transient loads like suspension forces? Will this tube be placed in bending (not so good) or is it being subjected to compression (good) or extension (better)?

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