Wednesday, July 2, 2014

Long Wheelbase resumed

Okay, where'd we get to? Somewhere or other I got distracted. - Actually this isn't true - what really happens - always - is that I find the smallest, tiddliest job and spend weeks staring at it wondering if there's an easier way. There never is. I just have to Get On With It.

In this particular instance it was how to mount the seat. So I did. First I had to calculate (guess) where the chain run goes, and then dodge it with the seat support. That meant welding it on the back of the base, not beneath the base.

Note favourite welding clamps: inner-tube strip. Jigged with bits of wood screwed together to ensure parallel sides ten inches apart. Overall seat width = 12"

Next, something to stop the seat support flopping over sideways.

... precision cold-set  (okay, whacked with a hammer)...
 and welded to the frame.

About now it occurred to me that I might, just might, not get the angle of the seat exactly right at the first weld. Actually, not might at all. I never have; never will. Ten miles into the first ride I'll know it's wrong. Slightly wrong, but wrong. Twenty miles and my back will be killing me. Dead.

All of which I didn't want to think about but now had to. So another week of staring dumbly at it before it occurred to me that the 1 1/8" seat support is the right diameter to sit neatly inside a retired head tube, and those I have in abundance.

 Sacrificed Raleigh head tube, plus one of two U-bolts

 Notches filed to weld titchy tubes for the U-bolts...

 ...and U-bolt tubes welded...

...and the whole welded to the frame. Now the seat can tilt.

So the next bit of complete engineering paralysis - if I can dignify anything I ever do with the epithet engineering - concerned how to use the former seat stays of the mixte frame, as seat stays. - Gah? - so I'm repurposing a thing to be what it already is. God I'm stupid. - Anyway the complication was that the Frenchmen who make Peugeot frames use 13mm OD tube, which is 0.3mm bigger than the half-inch ID tube I had. But luckily Messrs Huffy turned out to be generous in their half-inch tube,

and the already chopped-up bike yielded two bits that would slide over the seat stays. By cunningly keeping the ends of the bridge between them (above) I had some sticky-outy-bits to file neatly to accept a couple more bits of tube -

- which made the welding altogether easier. And here they are, one of them already drilled and hacksawn ready for the clamping bolts -

Then all that was required - another week's dithering - was to figure out how to weld the back seat support...

and close the ends off...

and get it in the right place. Which I dismally failed to do. Because I'm useless. It was a quarter of an inch too high.

So I made the extra little bits to screw the slidy-clampy-bits* out of the Huffy dropouts and welded other clampy-on-y-bits to the slidy-clampy-bits in a sticky-outy-sort-of-way so they'd all fit. Approximately. There isn't a pivot at the bottom of the seat stays. Some bending must perforce take place, but it won't be much.

And I screwed them together with 5mm bolts which, I believe, conversation with my brother who actually is an engineer having suggested, have a shear strength of about a third of a ton**. Which I don't weigh.

And conversation with Matt*** at the bike shop yielded a 42mm back tyre, which I rather hope, may make up for No Suspension. - We shall see. -

Anyway, here it is, roughly ready to start turning into a bicycle.

From behind...

and from the side.

*slidy-on-y-bits and clampy-slidy-bits are Highly Technical Terms, strictly used by recumberent (sic.) builders. (Shut up, Mrs. Hague.)

**actually he said a 6mm bolt has a shear strength of half a ton. But six sixes are thirty-six, whereas five fives are twenty-five, and twenty-five over thirty-six is about a third of a ton.

***who rides up Marahau Hill in ten minutes. Hmmph.

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