Monday, August 31, 2009

Tandem

I think my wife wants a divorce. She has given me permission to build a tandem. - Actually she didn't give me per.. - I just got some mountain bikes and got on with it.

The way you make a tandem is this. First you re-read Martin van den Niewelaar's article in the Feb 2008 newsletter of KiwiHPV, and then you re-read Sheldon Brown http://sheldonbrown.com/tandem-build.html, and then you re-read John Allen http://www.bikexprt.com/bicycle/tandem.htmand then you head for the dump at Mariri.

With a name like Martin van den Niewelaar you are required to live in Christchurch which is reassuringly flat. You're 1.8 metres tall, and the person who's (probably) thinking about divorce is a 1.6 metres tall fully trained German violin maker http://www.violin.co.nz/links.shtml which I still find difficult to believe. What are the chances of finding a fully trained female German violin-maker in a country with a population the size of Birmingham? - As a matter of fact I bought an old Stradivarius in a junk shop here, signed with the date - 1776 - written in by hand, a trifle baffling since any reputable forger would know Stradivarius died in 1737. - What's odd is it does have a nice tone. - What's odder is it's a 15/16 size, so if anyone's a particularly small violinist in need of - anyway, this isn't getting us very far.

Martin told us his and Hanna's heights in his article about making a tandem, it being relevant, but my wife nicks all my bikes so I knew I would be able to get away with two frames about the same size. And luckily enough the dump had just been freshly filled. The Police had evidently run out of room in their garden shed. Some of the thirty bikes still had Found Property Label, Police, For Use With Form 263 tied to the handlebar, which label has (economically) printed on the obverse Exhibit and Miscellaneous Property Label (for use with Pol. 268). Next time I get prosecuted for something juicy and the Exhibit is presented to the Jury I shall cunningly turn the label over and say I found it. Whatever it is. Gun, bike, lead piping. - Matter of fact Colonel Mus- well, John actually - found a large adjustable spanner on a bike ride a month or so back, and recognising the ute off which it had freshly fallen, hied him along to the relevant farmer who didn't even thank him. $45 the spanner was worth. (I'll advise him to use it in the kitchen. Farmhouses in New Zealand don't have a billiard room.)


A perfectly good gentleman's mountain bicycle

Most of making a tandem comprises worry. You worry about meaty front forks. You worry about cutting the wrong bits of rear stay off. You worry about whether 36 spoke MTB wheels will be up to it, and you worry about the geometry going wrong because you've cut a bit of tubing either too long and you can't be bothered to file it exactly to size or that you've cut it too short and the finished thing will look like a hog.

Most of my time is spent saving fivepence by splicing bits of tube together. I do this because whenever I see a sawn-up bike frame I think about how long it would take me to mine the ore, smelt it, and come up with a perfect piece of tubing. Making tubing by hand is astonishingly laborious. When the first gas pipes were laid in England, gunmakers were the only people who knew how to turn a lump of iron into an air-tight pipe (clue: Damascus barrels), and it is reported that the first gas-pipe was musket-barrels welded end to end. When once you know a thing like this you can't ever bring yourself to cut into a 20 foot length that you keep for just such purposes.
Oval tube prior to splicing.

Preparing the donor frames mostly comprises removing bottom brackets. I advance the Middleton Theory, which is that there is a mischievous elf who goes around with a spanner tightening pedals, stripping the thread in cranks and hammer-forging the right-hand cup into the BB shell and when he's done with all that, he pours dilute zinc chloride into handlebar stems. Come to think of it, John found his spanner. Hah! Where's the Araldite? Two can play at this game. He'll be amazed at how irritating it is to find a washer epoxied all the way into the lock of his ute.


Two perfectly good gentlemen's mountain bicycles, shortly after coming into my care.

(I have retired from politics, by the way. I learnt yesterday that 'not being in Parliament is not a handicap at all' which tells the British HPV membership all they need to know about Winston Peters the last foreign minister who - ahem - lost his seat, along with those of his entire political party, at the last general election. - New Zealanders do not need to be told about Winston Peters. They already know.)

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