Wednesday, May 28, 2014

Joining tubes

It did not rain tomorrow. Nevertheless I spent the whole of it welding. And since the object of this exercise is not so much a long wheelbase bike - that is a mere byproduct - but the recycling of old frames, we were into High Satisfaction Mode.

First to the seat supports. Bending tube, we have established, is not easy. So I look for bits that are already bent. Here's a suitable frame: a child's Huffy, where the chainstays are 3/4" 18 gauge.

Unfortunately I had only the one Huffy, so the support for the seat base can be the top bits of a perfectly good gentleman's mountain bicycle front fork. Here it is with the bottom of the fork legs snipped off, and the steering tube also snipped off.

The way you join tube, canonised by the BHPC about thirty years ago, is to insert a short stub and weld it in place through holes, a technique known as plug-welding. I've found with my MIG set-up that any hole smaller than 4mm tends to fail. The hole fills up before the substrate metal gets a chance to weld.

First I weld the stub in one end, then hammer the other end onto the stub. (With a big hammer. Whack whack whack, Mr. Knight. Precision engineering.)

Then the plug-holes are welded up, and the ends of the two tubes welded together.

Next, to an examination of all available frames. One I particularly treasured was an Australian frame bearing the auspicious name Ricardo. Unf. I couldn't get the seat post out. I had long ago tied a bit of inner tube over the end of the tube and poured Drano into it to dissolve the seat post, but it had only partly worked, and the BB shell was now full of rust, so feeling brutal I sawed it up. Nice thin-gauge Tange tubing, too. It occurred to me that a bit of heat might free up the seat-post, and the blowtorch provided this heat and the Drano started to bubble, so I took it outside to tip it away and found that it solidified as it fell out of the tube. It wasn't bubbling Drano at all. It was molten aluminium. And returning to the workshop there was smoke everywhere and I discovered that the molten metal was sitting in little blobs all over the place incl. the bit of carpet I keep there and incl. ten feet away next to the lathe. How I managed not to spill it on my feet is a mystery. I'm normally pretty good at hurting myself with easily preventable mishaps. Last week I hacksawed the back of my hand. Difficult trick to accomplish, but I managed it.

An application of angle-grinder revealed that whoever brazed the Ricardo together hadn't done much cleaning of the joints. Several of the lugs had brass at the edges but no brass inside the joint. Just rust.

Nice guarantee, though. Amazing what rubbishy joints manage still to work perfectly well for the lifetime of the bike.

Did I forget to illustrate my fantastic method of mitering the crossbar to incorporate the steering pivot? Here it is. Slits in the tube end, pliers to bend it to shape, lots of bits of angle-iron and box section and clamps and rubber strips to hold everything in line, and then weld on top of the bent bits of metal to conceal everything from the critical gaze and caustic remarks of Mr. Knight.

To the steering head. My first donor 20" fork turned out to have a horribly bent steering tube, and the second one seemed to have a weird sized head bearing set which was no longer present, so I had to find another fork, for which I had no head tube. However friend Huffy yielded a head tube, albeit too long. The head tube needs to be 1 1/2" shorter than the fork's steering tube. The only way I could machine the shortened ends square to the bore was on an arbor, turned for the job out of a stick of firewood.

Then off with all the paint (fire, wire brush) and more tube surgery to improvise lugs.

Then remember to put the BB onto the crossbar before welding the frame together.

Lugless joints + MIG welder + me as the operative = worry. So I gusset all the joints, which is nearly as good as a lug, and better because then Mr. Knight can't see the welds.

The gusset is only ever welded at the sides of the tubes according to Mr. Foale's book, never at the ends of the gussets. Otherwise the tube itself is weakened, and at its weakest point, too. Besides, welding along the sides of a tube is very easy.

First I tack-weld the gusset in place, and then hit it with a hammer until it fits. This delicate process is known as cold-forming.

Finally the sides of the gusset are welded in place. And here's the finished frame, with end-welded Ricardo downtube:

Next we have to shorten a steering tube for the intermediate handlebar. Same process as before, with the added dignity of squaring the ends on the lathe so that the bearings eventually run parallel to one another. This isn't strictly necessary in a low-stress pivot, but it's readily achievable. Then snip off a handlebar clamp from somewhere and weld it in place.

Finally start to think about the rod that will connect handlebar to front fork. The Ricardo frame provided some beautifully light seat stays: they will do, welded end-to-end. Interesting to see that there was so little brass on the bridge that - well, in fact, one bit had no brass at all, just rust. Very reassuring, that. The bike had been well-ridden when I came by it, and if a hard-ridden bike survives with negligible jointing, then my gussets ought to hold.

And now, alas, I have caught a cold, and need being felt sorry for.

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Saturday, May 24, 2014

Long wheelbase bike: construction

It has rained all day. I have welded all day. Here are the useful 'structions to make a bottom bracket for the LWB bike. (I entertain the vanity someone will want to know.) The photos can tell the story. All you ever need to know is that the front derailleur mech needs a post at 61 degrees from the chainline. - At least, I hope it does. -

First, select a donor bike for the BB shell. These days I check that the left and right hand cups are parallel. Once upon a time this was guaranteed, but in recent times a number of bike frames have come off the hooks in the rafters where one or other thread has lost interest in parallelism, and even brutal force used on a plastic-shelled sealed BB axle has failed. Such bikes attract the attention of the hacksaw and the BB shell is put to one side as Whucked. (Whucked: a word understood only by New Zealanders. I offer no explanation. In polite circles people say 'munted'.)

Yet another bike that I was given, no doubt because it was so heavy.

This particular bike had, on dissection, a seatpost long enough to be a hazard to aircraft. I was most surprised. It may have contributed to the vast mass of the bike when it was given to me. Luckily it also yielded a useful length of 38mm tube for something else, and a seat post clamp that is about to be repurposed. If I ain't going to have an adjustable seat I shall (probably) need an adjustable BB. Two other bikes also had their seatpost clamps filched to this end.
 Donor seatpost clamp. You Dremel through the tack-welds to free it.

 The support plates are 3mm thick

 Brave attempt to align support clamps. Too fiddly; it didn't work. 

 Cruder, but more successful

 The idea is to ensure the BB ends up square to the bike.

 Here we are, welding commenced

 Favourite welding clamp: the inner-tube strip

 Held in line on a spare bit of tube

 Ends welded on, and now ready to attach.

The crossbar will need means to pivot the handlebar. I snipped a piece of head-tube-and-crossbar off another donor bike, cut the head tube short, machined the cut end square in the lathe, and welded it back into the incipient crossbar.

 A beautiful bit of welding. - Shut up, Mr. Knight.

And on with the BB,the seatpost clamp wedged open with bits of wood. (Applewood, natch.)

We shall see if it rains all day tomorrow.

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Thursday, May 22, 2014

Long Wheelbase Recumbent

So, gentle reader, you thought I was clever. Try again.

You thought my wife was clever too. Try that one again.

My wife says some very strange things. The other day she said to me
"You need to clear out that junk. D'you really need a potato on your workbench? Why have you got a lipstick?"
For a wife to posit that junk needs to be cleared out shows astonishing feeble-mindedness; for anyone to fail to perceive the use of a potato or a lipstick on the workbench is remarkable. Nevertheless she is in my Good Books at present because she found the 14mm spanner that I put on the registrars' bed when changing my saddle last week. (There are several registrars. They have to share the bed. - Sequentially, not all together.) I had thought it was Kairn Peter again, erroneously conceiving that anything left within the confines of the shed but not actually secured with nail or padlock was merely evidence of my generosity. - He called again yesterday, and I had to pop out of the workshop hurriedly because he was popping right into it, and since he asked (again) if I had any work for him, and since he knows full well I don't, I think it's his standard ruse to escape suspicion when casing any particular joint. I am quite fond of my tools and don't mind at all if Kairn Peter leaves them where they are.

Anyway, the old boot's clear-out hint has stimulated me to turn a lot of unrequired bike frames into useful steel tubing, and having a fondness for long wheelbase bikes I thought I'd use some of it at the same time. It is factually correct to say that I don't need another bike; it is however irrelevant. Ever since I learnt that Mr. Knight once owned Mr. Ballantine's Avatar 2000, the one on page 24 of Richard's Bicycle Book which first made me fall in love with the idea of recumbent bicycles, I have liked to have the odd LWB kicking around. And old tubing is the perfect excuse, along with Anna Joz's broken Peugeot, a mixte frame which snapped at the stress concentration caused by the Frenchmen drilling through the downtube to accommodate the rear light's wiring. (Frenchmen should stick to growing onions. Or being shot by Englishmen with longbows. I don't mind which. I'm not fussy.)

To design a simple LWB you automatically assume a 20" and a 27" wheel. The front wheel is lightly loaded, and lacking suspension the back wheel needs to be big. A LWB with no suspension to clutter the design ought to be a quick weekend's project. Wrong.

I start with the chainline. This needs to run in a straight line from 4 5/16" above the bottom bracket centre to 2 5/16" above the rear axle. Neither handlebar nor seat may occlude this line or you need a pulley wheel as a chain deflector. The BB is made as high as possible relative to the seat, the only mistake of the Avatar 2000, where the BB is lots lower. Comfy, but slow, and we don't make recumbents for slowness's sake.

The centre of the BB must lie outside an arc 18" from the front wheel axle to prevent warfare twixt steering and feet. The seat angle has to be 34 ½ inches from the centre of the BB, or I can't ride it. (I'm not interested in whether you can.)

Along with the Known Fact that you'll need 1 ¾" trail, and the other Known Fact that kids' bikes' front forks always have 1 ½" rake, all you have to do is measure the various bits and the bike will design itself. (Oh, and the Kn. Fact that a 20" wheel is only 19 inches in diameter.)

Except for one thing. Which is that when you convert a one-tenth pencil drawing into half-a-dozen bits of steel, all sorts of mysterious inches appear and disappear and a great deal of head-scratching takes place. I know not why this is. Which is how we establish that you need to Try Again if you ever thought that I was clever.

Anyway, here's the drawing.

And here's the Much Better Idea, which is to make a very simple wooden jig and fix the front and rear forks to it and work from there. Simple. Wish I'd thought of that ages ago.

And I am making this in great haste because civilization is doomed and going to crash horribly. I had proof yesterday. I was going past Brooklyn School and the caretaker was using a leaf blower to blow leaves from the pavement onto the road. When leaves can't be untidied from one public space to another public space without recourse to a petrol motor, you know civilization has lost the actual plot. So it's a good job that Mr. Knight has finished his bicycle because he can now ride without fear of punctures.

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Saturday, May 3, 2014

Marahau Hill

My current lunchtime ride is the Marahau Hill loop, a chirpy hour and twenty minutes which you can only do in the spring and autumn. In the winter it's too icy and in the summer the merry young tourists fling beer bottles from their motorcars in approximately inverse proportion to their neuronal makeup. At the moment it's wonderful. The hill is a seventeen minute upward grind from which you will correctly deduce my feeble fitness levels cos the young athletes do it in fourteen or less. Down t'other side it's five adrenaline-filled minutes of alternating front and back brakes lest the heat from the rims swells the tyre over the bead. Three times this has happened to me and I do not wish to experience it again. When you get to the bottom there's always a gentle onshore headwind, and then you turn off to Split Apple and along the alpine road to Kaiteri, the hilly bits now mild and pleasant in contrast to the Hill itself.

The other day I happened on a new and interesting sight. Some small girls were carving graffiti into one of the many sandstone bluffs before Kaiteri. The interesting sight wasn't the small girls: it was their parents, parked at the side of the road and standing watching them deface the countryside with evident pride and pleasure. I do not know who they were, but I'm prepared to hazard a guess that they were the sort of parents who would christen their daughters Ella, Chelsea and Sophie Madison Hill.

I don't think they'd call their daughters Ben O'Connor,
and not many parents would burden a girl with the name Josh Hughes Is Gay.

And on a not-entirely unrelated topic, I'm moved to confirm that it was indeed Kairn who made off with the pink infant's bike. - The pink bike of the infant, not the bike of the pink infants, though mayhap the infant was pink too. - They often are. - Kairn had dropped in on me, all unexpected, last week. He knocked on the door - actually knocked - and asked if I had any work for him. Alas I couldn't help in that respect, but I enquired as to how his bike was, and he showed me it, a black gentleman's mountain bicycle, though - from the evidence of the mis-matched and non-functional gear changers, not a perfectly good one. He said he used it just for work in case anyone took it, and he had a perfectly good one at home, except for the crippled back wheel. I suggested he drop it in on me and I'd fix the back wheel for him. But he didn't. And the last four days I passed his work-bike flung up against a gate at the foot of Marahau Hill, and I did wonder if his new job was systematically hunting pigs up the gully below the quarry.

Now it happens that Ron, whose bike I fix whenever it goes wrong, had recently given me his son's old bike which he would otherwise have thrown onto the town dump. "Can you really use it?" he'd asked, and I assured him that if I couldn't, I could probably take bits off it for spares. However with Kairn in mind I had pumped up the tyres and left it tucked well inside the overhang of the shed by the driveway. And this afternoon, just as I finished raking the lawn, I caught a glimpse of a boy in a hoodie going past on a bike, and, with that instantaneous recognition that develops in all cycling aficionados, I felt sure it was Ron's son's bike. Had the rider seen me? A few minutes passed, and there was a screech of brakes and some talking and my wife called out that I had a visitor.

It was Kairn.

"Um, I just found this bike round the back of your shed. I thought it might be yours so I brought it round for you." Kairn doesn't have the highest of IQs. In fact I don't think he has an IQ at all.
"Yes, I think it is," I said, not troubling him with the information that he could only have found it had he been inside the shed at the time. "Do you want it?"
"Oh, I was wanting to borrow something to go into town."
"I saw your work bike at the bottom of Marahau Hill the other day."
"Uh, Blackie took it. He said it was at the bottom of the hill."
I did not ask who Blackie might have been, but said "You can have that one if you like. It was given to me. But the bottom bracket's loose, so if it's too bad bring it back and I'll fix it for you."
"Oh, thank you" said Kairn, and off he went, leaving us chuckling over dinner.

Half an hour later a car turned up. It was Kairn's father-or-guardian-or-caregiver.
"Has Kairn Peter been here?"
"Yes, he came to borrow a bike. I gave him one that had been given to me."
"Oh right. Good on you bro. It's just that he's a little shit at the moment with bikes."
"That's okay. He told me he's got another bike, with a crippled back wheel. I said to bring it along and I'd fix it."
"That's my bike. The back wheel is wobbly. I heard that you can straighten a wheel by putting it in the freezer."
"I've never come across that. But if you drop in the wheel I'll fix it for you."
"Oh thanks, bro. I'm John, by the way."
We shook hands, and off he went.

We'll see what happens. And I'll leave another bike out for when Kairn is next stuck for a ride into town.

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