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Tubelessness 

Frankenbike. GT LTS 1 rear, Marzocchi Bomber front, Scott Peak middle, dutch shopping bike bars, cheap flabby Phillips seat, truly fantastic Kenda Karma tyres, various other bits of junk from the Bike Heap. No back ache, no arm ache, no neck ache, not very fast.

I have now fitted tubeless tyres to Mrs My Wife's new mountain bike. You run a plastic liner round the inside of the rim to seal the spoke holes and fit the tyre with sealant inside. - Of course you don't do it yourself lest you get ucky bits of sealant on your fingers, not if the shop is kind enough to do the fitting for no charge, which my shop is, cos Josh is a Good Chap. Punctures deal with themselves until a big rip in the carcass requires an inner tube. Apparently.

 

The rolling resisance, as compared by rolling down tarmac road hills together, is equal to what Mr Knight has taken to calling my Frankenbike which runs exceedingly thin-wall tyres. A bit disappointing since hers is a 29er and mine's a 26er, but then Frankenbike does roll amazingly well. But subjectively on the orchard dirt road, Mrs My Wife's 29er feels a bit like riding a racing bike on tarmac, and it feels much easier to ride than Frankenbike. Much easier.

Frankenbike's tyres, for the record, are Kenda Karma. You can't get them in NZ any more. I have two pairs. We have a friend who is a perfectly good gentleman who - you will deduce - has a perfectly good gentleman's mountain bicycle (would it be a Giant Trance?) and when he last popped in I stole it and rode it round the orchard paths. He runs or'nery but good quality tyres which I believe he may have bought for their longevity, he being a fellow notoriously tight in the wallet department, and they were truly hard work to pedal. Thick side walls. Lots of hysteresis.

After riding at the Kaiteriteri mountain bike park yesterday in her company, but without riding her bike, he had this to say about my wife's 29er:

1. She has the wrong gearing. She should have the same gearing that his MTB has.
2. She has no back suspension. She should have back suspension the same as his MTB has.
3. Those big wheels make the riding position too high. She should have the same seat height that his MTB has. (She got off and compared the seat height. It was the same as his. )
4. Those great big wheels make the bike much harder to manoeuvre in tight corners. She should have the same size wheels that his MTB has.

He then said several of his friends have 29ers and love them. As soon as I can find one I shall fit a wicker handlebar basket to Frankenbike and ride it to Kaiteriteri with him if just for the pleasure of hearing his verdict. (The mountain bike park is on Youtube, natch: http://www.youtube.com/watch?v=r4Caq2sE2iI.)
Saturday, September 24, 2011 8:27:00 AM Categories: mountain bike Tubeless tyres

29er 


Owing to circumstances beyond my control - birthdays and that sort of thing - it was required, as the textbooks have it, to provide my wife with a brand new perfectly good gentleman's mountain bicycle, and natch I took her old one, wot she'd mistakenly thought I'd bought for her and wot, therefore, I'd been unable thus far to ride, up to the shop to see what would fit. Her views being irrelevant the purchase was effected, but nevertheless she was dead pleased to find herself the owner of a 29er. A rear rack and boxy thing got fitted, to the great mirth of all the young athletes who eschew such ungainly protuberances and who themselves spray bananas and energy bars and spare inner tubes out of their jersey pockets whenever the bumps are too exuberant.

If one is of a meddlesome disposition, then this sort of adventure is just an excuse for experiments, and since we were in new territory I thought I'd extend the experiment. The only person I know who does tubeless is Mr English of our colony of America. Actually he made his own 29er weighing a feeble 8.4 kg, the scamp, and here it is:


As you see, single speed and belt drive, which he tells me is silent, and which as far as I can tell is fitted to the frame by magic. - Anyway, I emailed the man:

Now then, Rob,
Mrs My Wife has got herself a Specialized somethingorother 29er mountain bike wherewith she's much pleased. It was very cheap. About a thousand dollars. New Zealand ones .The bike shop boys were babbling about tubeless tyres and how their rolling resistance would be vastly superior and whatnot, so I want an informed opinion. Easy to fit? Rubber rim liner better than plastic? Tube sealer works sealing punctures? Lower pressure equivalent to higher pressure for rolling resistance on-road? Any other issues?
Ta,
R

And the man emailed me:

I have used tubeless mtb tyres quite a lot. Sometimes I can get them to seat with very rapid use of a track pump, but sometimes it requires a compressor. But once seated with sealant in, they work very well. Unless you don't ride the bike much in which case the sealant dries up into a big puddle of latex in the bottom of the tyre. I wouldn't consider racing without them (no pinch punctures, nice low pressure (20lbs), other punctures seal up), but I don't mountain bike enough these days to bother the rest of the time. I haven't yet tried road tubeless, but reports are good so far, and in theory they should offer superior rolling resistance, but I haven't actually seen any data yet. For sealing the rims on the mtbs I just use NoTubes yellow tape - very light and does the job. Their rubber rim strips work nicely too, though a bit heavy and I also seem to eventually rip the valve stems out of them.
We did a 10 mile ride on the new tandem t'other day and it felt better and better as we went along. Drivetrain is very nice and quiet and smooth. A little bit of wag in the back, so I am going to increase the lower connector tube to 1.5" before I paint it. The titanium tubes there do really take the edge off of the bumps though.
Cheers,
Rob.

The tandem concerned is this one:


I keep meaning to build a recumbent tandem myself but unf. I'd recently secreted two cranks in the car of Mr Schroder of our colony of Stoke-or-Richmond-or- Nelson-or-somewhere, and the other day he couriered them back to me rather neatly drilled and tapped at 110mm and now I can't think of an excuse not to build a front-wheel-drive 29er of some sort, which, with these cranks, will be sort of like a 45 inch gear fixie. If I've got the sums right. Which isn't usually the case.
Saturday, September 24, 2011 8:23:00 AM Categories: mountain bike Nigel Schroder Rob English tandem

Fantail 

 It is Winter. (Have I mentioned this?) It is cold. The moth that fluttered round the kettle this morning seemed out of sorts as if he'd prefer to have stayed in bed for a few more months like a teenager. He resented being captured in cupped hands and when I chucked him out of the kitchen door and he was instantly plucked from the air by a fantail, I saw he had a point. New Zealand possesses these tiny birds just like blue-tits who flutter a yard away wherever you walk, on the lookout for disturbed insects. As soon as they take to flight you just know in your bones that they are called fantails; and so it proves. Fantails are not very clever and whenever they come into the workshop they spend hours attacking themselves in the mirror and perching, slightly baffled, on the badminton racquet below for a rest. The Maoris tell me it's bad luck to have them indoors and that's true, because a month later you find they've been dropping corrosive white chemical onto your supply of silver steel. Chickens are not the only bird that don't just lay eggs.
 
My workshop is full of anomalies like badminton racquets but the mirror isn't an anomaly. It's used for checking one's riding position while building useless fairings, and it makes the workshop twice as roomy, except now it doesn't because I cover it with a garish pink tablecloth to stop the fantail despoiling all my reamers. Why does anyone go to the trouble of making pink tablecloths? My life is full of mystery, including where the pink tablecloth came from. Another mystery is why my cycling tee-shirt has to have a large plastic tab sewn onto it bearing the legend Eden Project. I thought the Eden Project was about recycling and sustainability and whatnot. Large red plastic tabs cannot be recycled, add weight, serve no purpose, and itch. It is as if clothes designer executives have a group session every Monday morning to decide what brainless irrelevancy they can perpetrate upon an insentient and gormless public that week. What they need to do is take lessons from bicycle manufacturer executives, who, as we all know, have group sessions every Monday morning to decide how to make components that work flawlessly and are compatible with all other components. That is how Shimano Index Systems work so well, and why I fitted one to my new perfectly good gentleman's mountain bicycle.
 
Unfortunately it didn't work.
 
Unfortunately the inner chainring needs a whisker of clearance against the frame so that you can turn the pedals round, and unfortunatelyer Shimano's executives didn't think of this on their Monday morning group session so when I tried to fit a front mech I found that the parallelogram frame is actually too short to lift the chain onto the big chainring. And to rummage for alternatives in the box of spare front mechs I had to move the bandsaw and the table promptly broke off, examination proving the attachment lugs to be made of some flimsy brittle substance approximating to metal but possessed of No Strength Whatever.
 
 Shards of bandsaw
 
 
And two minutes later a temporary German damsel (1) came round the corner wheeling a bicycle with a broken chain-link.

 

Shards of chain

But at least she had the great good sense to keep the chain. The last time I heard of a chain-link breaking was in a phone call from a friend in the village where we lived in England and he had thrown the chain away, being unacquainted with the phrase 'weakest link'. The curious thing was that he was a certain Professor H********, head of department at the largest university engineering faculty in the country. I now start to wonder if his special field of research incorporated bandsaw table lugs, tee-shirt technology and the corrosive metallurgy of bird-lime. I don't think he was a consultant at the Shimano Front Mech Factory.
 
1. She goes back to Germany in ten day's time, slightly chilled and probably exhausted from skiing

 

Saturday, July 10, 2010 10:33:32 AM Categories: engineering problems mountain bike New Zealand

Hacksaw distortion 

 
B*llocks it's cold. When I say it of course I am referring to the ambient temperature, not to It, which might be implied by a wilful misreading of the proximity of 'B*llocks' to 'it's cold.' Mind, if we're going into intimate details, cycling along the West Bank Road does tend to chill certain contiguous organs, and since they then all shrink to the size of something that can be comfortably concealed by the next fullstop, I shall have to stop automatically deleting those helpful emails from Daina Yukiko Devinehlq offering me Our enlargement pills can show you, has the are recently. The West Bank Road gets no sun in winter and you can always find plenty of black ice which yields one of winter's pleasures, viz., boy racing. You indulge in wheelspins and skids and doughnuts and all manner of exciting road adventures and yesterday I suddenly noticed in my little mirror that I was being followed by a big 4WD ute. It was driving *very* cautiously. I think he'd spotted what I was doing, and abruptly realised he was in some danger if he drove at normal ute speeds. He didn't overtake for ages, not till we reached a bit of dry road that had been warmed by the sun.
 
Cold, so time to do a little perfectly good mountain bicycle hacksawing. Sometimes I hacksaw to harvest bottom bracket shells and sometimes I hacksaw to get steering tubes and sometimes I hacksaw out of curiosity to see if the builder inexplicably filled all the frame tubes with molten lead or whether there's some other explanation for outrageous weight.
 
Mountain bicycles have the two advantages that people are constantly throwing them away and that they don't use obscure British 1940s BB threads and that you get cantilever stubs off them, so that's three advantages, and that they yield long cage rear mechs, so that's four.
 
Here is a Useful Tip for new cheapskate recumbent builders: always get perfectly good ladies' mountain bicycles in preference to perfectly good gentlemen's mountain bicycles. None of the parts will be worn out. Not even the chain. Ladies have no idea at all how gears work, so though their bike may boast fifteen of them, only one gear will ever have been used in its whole life. Once top gear has been achieved the lady will labour slowly along with her kneecaps popping, and being unaware of the possibilities of going back into a lower gear, will regard the bicycle balefully at the end of the ride and thereafter select the car for all future journeys. After seven years her husband will undrape the dust-laden blanket from it and put the machine, with crumbling brittle tyres and slightly rusty cables but otherwise intact, on the trailer and take it to the local Household Refuse Recycling Centre to be crushed into a skip. And here is another Useful Tip: as bicycles are only ejected from households of a Sunday morning, and as council officials can't abide for the public not to be forced to queue, you wait outside the town dump and ambush the line of cars at 10.40 am and offer every third trailer-load two quid for his bike. He won't accept the two quid if you try to look like a poor student bent on cheap transport. Do not discuss recumbents or hacksaws. Bike-chucker-outers won't give you them if they see the glint in your eye and the hacksaw in your hand.
 

 Distortion of frames after hacksawing 
 
The interesting part of hacksawing a bike is how much the tubes spring apart. They do this every time. About 3.175mm. Internal stresses from the welding. The other interesting part is finding out that the steel is 1.5mm thick. Actually you can ascertain the wall thickness of frame tubes without recourse to a hacksaw: you poke a vernier into a bottle cage hole and then measure the OD across the same point. It amazes me that cheap mountain bikes have tubing of 1.5mm thickness and it amazes me that the OD of one tube will be 38.1mm and the other 50.8mm and it amazes me that bicycles this strong, which cannot physically be destroyed by any means not involving asteroid collisions, always bear the legend 'WARNING THIS BICYCLE IS NOT DESIGNED FOR OFF-ROAD USE OR STUNTING'. Then what is it, pray tell, designed for? - well, actually it's designed for propping up a blanket next to the freezer in the garage for seven years, that's what.

Saturday, June 19, 2010 11:58:08 AM Categories: junk collecting mountain bike

A perfectly good gentleman's mountain bicycle 

 TransportNZ has decided to maintain State Highway 60, not one lane at a time but the entire section. And to everyone's surprise they have taken it away. The whole highway. For the last month a mile of road between here and Motueka has had no tarmac at all and is a sandy muddy swamp and accordingly Mr Knight, who knows about these things, has instructed me to acquire a perfectly good gentleman's mountain bicycle. Nobody in their right mind builds such a thing but unf. I have a crippled neck and mountain bicycles suitable for perfectly good gentlemen have the handlebars about a mile too low and make my arm all numb and tingly. (Attentive doctors of medicine will immediately diagnose C7.)
 
Besides I already had the makings of a perfectly good gentleman's mountain bicycle. I had some Marzocchi forks. These cost but little because a previous owner - a moron, if we're being straightforward - had attended to the stem with a hacksaw. (I offer up to the world Middleton's Second Law, which is this: 'Things are seldom improved with a hacksaw.') Fortunately I am a genius and promptly extended the stem with a one-inch tube which inserts tightly and when plug-welded to another stem lies perfectly straight.

 
A plug-welded stem extension

Moreover 'arry, who ran the bike shop in Loughborough (no-one pronounced the 'H') once gave me the back of a bent GT LTS. - This is a GT LTS which had a bend in it, not a recumbent form of a GT LTS, which clarification I make because there are all too many philistines who following a very doubtful and frankly rebellious parish in our noble British colonies - America - erroneously fancy that 'bent' is an acceptable abbreviation of 'recumbent.'  Which it is not. Bent is a word with negative connotations into which I shall not go. Recumbents on the other hand are a glorious invention of magnificent god-like creatures, viz., us lot.

And having a vast Bike Heap I have decided to weld all this together and I can assure you that this will necessitate my using the *uck word quite a lot because it always does. I will also waste most time on the tiniest little bit, and the smaller and less significant it is, the more time and the more *ucks will be spent on it. In fact I just spent two and a quarter hours attaching one of those plastic cable-guiding thingies to the bottom of the BB shell of the donor frame, because a previous owner - a moron and probably the same one - had removed the original and it wasn't a standard size and to make another one fit I had to use a hammer a screwdriver a hacksaw a punch two rivets the small end of a .223 brass rifle cartridge a 7mm spanner a 13mm spanner the hacksaw again an 8mm tap and some meths to wash the reaming tapping and cutting fluid off my best trousers in which I had rather foolishly entered the workshop. As there may well be a vicar reading this I shan't tell you how many times I said *uck but it was fewer than this morning when I found that my bloody wife had constructed one of her amusing Art Installations with all the crockery on the draining rack. We have this rule - call it My Wife's Second Law - that when she cooks I wash up, and when I cook I wash up. And should I demand my yuman rights and go On Strike of an evening she punishes me by playing that bloody Jenga game with the plates and coffee mugs and glasses and carrot-grater and lemon squeezer and anything else possessed of an outlandish and unstackable shape, and behold! at 7.55 am there on the draining board is a reproduction of Mount Everest in bone china.

Friday, April 30, 2010 10:49:11 AM Categories: brass cartridges maintenance mountain bike
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