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Posts From September, 2011

Tubelessness 

Saturday, September 24, 2011 8:27:00 AM Categories: mountain bike Tubeless tyres

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.)

29er 

Saturday, September 24, 2011 8:23:00 AM Categories: mountain bike Nigel Schroder Rob English tandem

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.
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