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Our German Girl has vanished, so there have been divers happenings relating to recumbency in the Southern Hemisphere over the weekend. Our German Girl is an exchange student who has appeared courtesy of the world's various Rotary Clubs; she isn't actually Ours; we sort of share her with various other families whom the Rotary Club deem unlikely to be child molesters. - We are not, ourselves, Rotarians, because we do not wear business suits nor feel the urge to meet every Tuesday evening with people who do wear business suits and I'd better go no further lest a Rotarian happen on this Blog and take offence. - Not that there's much chance of it. Rotarians are such folk as not, I find, greatly to interest themselves in recumbent bicycles, though if it so happens that one of them does I shall, on application, supply him with my brown paper bag. It must be jolly embarrassing to have the entire HPV world discover that you're a closet Rotarian. - Anyway I know for a fact that they don't because they wouldn't release a German Girl into the custody of someone who cycles up and down the valley with a bra on his head. (Actually our financial advisor reads this blog, though I happen to know that she's only a Rotarian in order to get the latest goss on which local lawyer is having an illicit affair with which other local lawyer but unfortunately she does not share the details with us or I would derive immense pleasure from revealing all here, though this would almost certainly terminate the entries because I don't suppose they have Internet facilities in New Zealand gaols.)(And of course our financial advisor wears a brown paper bag anyway, and has done ever since the sub-prime thingy.)
 

Our German Girl is the daughter of an actual Brain Surgeon. I mention it because it is so unlikely. How many brain surgeons d'you know? No, neither do we. But anyway further details about her can be skipped because she doesn't ride recumbents, which state of affairs you may depend will be remedied within the next few months.
 

With no German Girl to entertain the weekend was clear for Sam the Scotsman to pop over for some learned discussion on the topic of tandems and whatnot. Sam, Sam, pick up tha musket. (Obscure and irrelevant. Ed.) It will/won't be recalled that Sam has a broken trike and wishes to turn this into a recumbent tandem of sorts, using approx nil of the trike parts because approx nil of them are strong enough. Accordingly he has been busy popping in on the local bike shops assembling a collection of various 406 forks and wheels, and we now have a merry heap of components scattered about the workshop floor. And since our researches are of no avail to the world if we do not share them I advance the following info, some of which will be erroneous, some duplicate, and perhaps, just perhaps, some of it useful to someone in Afghanistania (1). Provided, of course, Afghanistanians' recreational interests do not centre on wearing a business suit of a Tuesday evening.

 
Imprimis. That Larrington man has a useful site full of recumbent tandems:
and if you can read Foreign, so has a Foreigner from Abroad:

Item. For $NZ87.50 you can buy a 48 spoke, 406 wheel on a 14mm axle, and you can winch the cones in and out respectively to make stub axles.

Item. The 14mm axles with sealed bearings have a shoulder on the axle itself, so you can't turn them into stub axles.

Item. You need whacking great big cone spanners for 14mm axles.

Item. I have lost my vernier calliper.

Item. I have found it. Why don't I put it back every time? Am I stupid? - Don't answer that one.

Item. Right, specifically you need 19.05mm cone spanners, 3mm thick. 19.05mm is 3/4 of an inch. Sit up at the back and pay attention.

Item. You can screw a cheap derailleur block onto a 406 rear wheel with a 14mm axle ($NZ99.95), but only by removing the RH cone lock nut and using a slightly munted axle nut, the munting performed neatly on the lathe, of course, and a spacer to lock the cone. It then becomes a pig of a job to remove said block, because the hole in the middle of the block-removing tool (don't I know any technical terminology?) is smaller than 14mm, so the entire axle has to be dismantled and extracted out of the RH side, which requires final careful tapping with a hammer to dislodge the protective dustcap that sits on the RH cone by friction. What a rubbish sentence. We need more specific technical terms than just 'leg-suck'. Did you ever do Airfix kits when you were 12? 'Locate the locating peg in the locating hole' was never entirely informative, and you always ended up gluing the undercarriage of your Fieseler Storch the wrong way round. - And while we're about it, did you ever try to use a Haynes manual to find out where to look for the fuel pump on a Mini that was always going wrong? Those diddly photographs had me crawling about underneath on the wrong side and the wrong end of the car with a torch, jabbing myself occasionally in the eye with a bit of oily dangly plastic pipe the purpose of which I never discovered. My father-in-law had a sensible approach to our Mini van, hacksawing a chunk out of the radiator grille to get at the oil filter which you could only otherwise reach if you had a second elbow half-way up your forearm.

Item. Where were we? Ah - more technical terms. -
 

Item. If you happen to enjoy the same seat position that I do, then the optimum height of the bottom bracket is 9 inches above the sitzhohe. - Sitzhohe is now the correct technical term for the lowest point on your seat. It has been the correct technical term for the last thirty seconds when I nicked it from Germany, and it would have an umlaut somewhere to make it look even more correct and technical except my keyboard doesn't have umlauts to hand and sitzhoehe looks clumsy. It is a better technical term than 'bent', which I see is still persistently used by those who know no better. There needs to be a Royal Commission, like the Academie Francais (no accent or cedilla key, either), to which American Persons can make supplication for new words. - er - Where were we again? - yes, the BB needs to be 9 inches higher than the sitzhohe and then with a 170mm crank, heel-clip at 4 inches will equal knee-rise at 4 inches.

Item. I just invented heel-clip and knee-rise too. Heel-clip is how much your heel drops below the sitzhohe (I'm enjoying this) during the rotation of the cranks, and knee-rise is how much above your shoulder the knee goes, both of 'em messing up your frontal area. We'd better settle for BB even though it isn't a bracket and isn't at the bottom of the machine any more.

Item. However N=1 which means to say this experiment was conducted on the only legs available, viz., mine, so if you chance to differ in any anatomical way from me, then I may be talking gibberish. I often am.

Item. If your pelvic girdle is approx the same as mine, any large upright member such as (shut up, Carol) the front part of a Z-frame cannot be closer than 8.5 inches from the seat angle.

Item. Seat angle is a technical term, too. It's the bit - well, it's usually the sitzhohe, except where the seat has a webbing base when the sitzhohe may sink below the seat angle. And (by experiment) the seat angle is usu. the body's centre of balance, if you're lying back comfortably so that the BB is indeed 9 inches above the sitzhohe.
 

Item. Heel strike (someone else's term. Where your heel hits the front wheel) is guaranteed if the BB is within 17 inches of the front axle. This for a 'nornery Q-factor (Hurrah! 'nother tech. term) and 'ornery 170mm cranks and a 'nornery 406 wheel with the 1 3/8 Primo tyre that Sam gave me the other day and it was a Jolly Good Thing he did because my Stelvio had delaminated.

Item. The seat base needs to point at the centre of the BB.
 

Item. The steering head tube is 1.5 inches shorter than the pivot tube thing of the fork itself. Hey, what does Archibald Sharp call it? - Here we are, p 297 - the steering-tube. Mind, he also refers to the 'top adjustment cone of the ball-head' and we'd all like to know what a ball-head is. (Shut up, Carol.)

Item. The cantilever bosses on forks for a 26 inch MTB wheel are just 5mm too high for those funny cross-over U brakes that they fit to BMX bikes. Wonder if we can make them fit? The pivot appears to be 46mm from the centre of the lowest brake-block mount, and it really needs to be 50mm. http://www.discountcyclesdirect.co.uk/popup_image.php?pID=6985

Item. No matter how carefully you measure seat angles and seat distances, it is impossible to draw them accurately to scale. Impossible. Totally impossible. Y'know those all-in-one carbon fibre frames incl. the seat? They use human sacrifice on a moonlit night with incantations round a cauldron to get it right. There is no other way.

Item. This list is now so boring I need either to Get a Life or to join Rotary. I shall draw a drawing full of technical terms instead.


1. Its new name, on no less an authority than the New Zealand Prime Minister. He said 'Afghanistanian Government' on the morning radio. He actually said it. I wrote it down at once. And since we're off-topic, why do New Zealand broadcasters refer to Her Majesty as 'Queen Elizabeth the Second'? Did New Zealand have a Queen Elizabeth the First that I haven't been told about?
Wednesday, August 12, 2009 11:59:29 PM Categories: engineering problems
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