Wednesday, October 10, 2012

Tandem trike trailer

Today I had occasion to cut up a Raleigh Twenty, something that should be done as often as may be, for in doing so one learns why Nottingham's district of Lenton is now full of students rather than Raleigh employees. The one-and-a-half inch main tube of a Raleigh Twenty derives most of its strength from the wall thickness, a hefty two millimetres.  And when you come to weld to Raleigh Twenty tubing you discover that among its other economic savings Raleigh dispensed with undercoat when painting the frame.  In these revelations lies the Great Secret of why bicycles aren't esteemed in Britain. When the accountants have control, they're crap.

This desire to saw Raleigh Twenties up is not a new departure, but I did happen to want a bit of meaty tube to form a link between two machines to create a tandem. This is not a tandem for me, you understand; rather it's a tandem for a chap who lives beside the aerodrome, whom I happened to meet one day when I saw him pedalling along on a home-made semi-recumbent trike, a machine blessed with two front wheels located on linked BMX forks.

I asked him who made it.
"I did."
"But you're disabled."
"No I'm not. I just haven't got any arms."
He turned out to be a retired judge. He'd been born with no arms. Nevertheless he had built a number of boats, and an ingenious, recumbent-ish trike with two front wheels mounted on Raleigh Twenty forks, linked with an aluminium pole, and a plastic school chair as the seat. I asked him how, and he said to my amazement
"Angle grinder."
Which he holds with his toes.

Anyway, he phoned me up recently to come and see the new tandem trike he's making. It isn't a trike so much as a self-powered trailer. The two wheels are from a ditched conventional trike conversion kit. The junk he'd screwed together to fix this to the back of his wife's bike was so chaotic - ingenious but chaotic - that I offered to weld some stuff together to tidy it up.

First trial by the builder, looking remarkably happy largely because he hasn't got a chain

As delivered to me in the middle of a rainstorm t'other day

His linkage is a chrome plated, slightly magnetic, turnbuckle. Maybe nickel-bronze? - Anyway, the bolt part of it is 7/16 (11mm) OD. It rotates in the thread to allow the bike ahead to lean. It has two other planes of movement and it does work - I rode the bike with him sitting on the seat behind - but I was worried, and discussed it with a consulting engineer who designs industrial machinery and who very kindly doesn't charge me owing to the fact that he's interested in unusual vehicles* and owing to the other fact that he's my brother.

We decided that since the turnbuckle isn't going to take much of his weight, which is carried mostly on the two wheels of the trike-part, it should be okay, but my brother suggested a safety chain or rope in case it breaks.

But we were both concerned with the aluminium tube from the turnbuckle to the back section, under the non-functioning rear steering head, so the Raleigh Twenty got itself turned into a sturdy boom with a sturdy quarter-inch-thick piece of steel squeezed and welded into it and then drilled out to take a sturdy bolt and I think that should do the trick.

*Here's one of the motorbikes he built

Labels: , , ,


Post a Comment

Subscribe to Post Comments [Atom]

<< Home