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Another Bike Flat: Michelin Hair

Rode around the big block on some errands, stopped at the Vassar Farm garden to haul some squash home, rode off… and the bike handled poorly. Well, with a few dozen pounds of produce in the panniers that’s not unusual, but this was worse. Yup, another flat.

This time, however, our daughter was home and could rescue me in the van. Back in the shop, I found this obvious suspect:

 

Embedded glass fragment

Embedded glass fragment

 

Once again, however, this wasn’t the problem, as the tire liner was barely scuffed. Those are glass fragments inside the gash, which might actually be the same one as before.

There weren’t any other pointy objects embedded in the tire, but the tube wouldn’t stay inflated long enough to find the leak. I took the tube upstairs, submerged it in a pan of water, and found a rash of holes. Not pinholes, not a failed tube, but a series of punctures.

 

Steel wire fragment

Steel wire fragment

 

Examining the tire liner revealed the cause: a strand of what my buddy DBM calls Michelin Hair poking through the tire liner. It’s a fragment of the steel belt from a car or truck tire, most likely shed from a disintegrating semitrailer recapped tire.

There is absolutely no defense against these things, because they have razor-sharp points on both ends where the wire fractured. When the tire picks one up, every rotation drives it through the rubber, the Kevlar belt, the tire liner, and the tube. The usual symptom is a slow leak, eventually followed by a row of holes in the tube as it shifts position under low pressure.

In fact, the tube had a slow leak since I installed it a few weeks ago after a tube failure. I wondered if I’d inadvertently installed a fold, but now I think I ran over this wire during the first few rides and it’s been getting worse ever since.

That tube is a goner! I installed another Schwalbe tube and we’ll see what happens; one has been working fine on Mary’s bike for the last three months.

Here’s a look at the steel wire from the side:

 

Steel wire fragment through tire liner

Steel wire fragment through tire liner

 

It was completely through the liner, with only a stub sticking out on the tire side. There’s certainly a matching hole somewhere on the tire, but it’ll be indistinguishable from all the other nicks and gashes.

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  1. #1 by Frans on 2010-10-23 - 05:18

    A semi-transparent tube? That has got to make it easier to find damage than the black tubes I’m familiar with. Is that a regular American thing or are they some kind of special tubes?

    • #2 by Ed on 2010-10-23 - 06:32

      That’s actually the tire liner: a plastic strip between the tube and the tire!

      They’re made of a tough, stretchy plastic that’s much more difficult to puncture than the tube, so that anything making its way through the tire stops at the liner.

      Search the blog for “tire liner” or just “Slime” (the trademarked name) to find several more posts: we use them in all our tires, but they’re not perfect protection.

      • #3 by Frans on 2010-10-23 - 06:59

        Oh sorry, I don’t think I’m familiar with those. That must be why my brain malfunctioned I’m afraid. I’m still trying to get over the fact that it’s tube and tire rather than “inner tire” and “outer tire” in English!

        A few years ago I installed a EUR25 Vredestein Perfect Flex System tire on my back wheel and I haven’t had any flats since. But then all we get here is glass shards and sharp stones; perhaps a pin in a worst-case scenario (though even that didn’t puncture it!) It does of course require some check-ups every now and then to remove things stuck in it, because otherwise they could slowly wriggle their way toward the volatile tube.

        That said, since I moved to Antwerp last year I haven’t really used my bike. Perhaps it’s heavenly to ride it here compared to where you live, but I’m used to the Dutch cycling infrastructure, the way drivers of cars etc. treat you, and here it’s just no good. If the treacherous rails of the streetcars and the generic lack of space for cyclists weren’t enough, there’s these so-called children’s heads (cobblestones) all over the place. Now I’m not opposed to riding my bike without sitting down, as if I were riding a mountain bike (at least if it doesn’t last too long – it’s still primarily a mode of transportation after all), but my poor city bike can’t handle it! The fender on my back wheel came loose (rust, but on Dutch infrastructure it wasn’t a problem), taking out the lights with it. So yeah, it’s a lot more dangerous for me to ride a bike here. Consequently I like it less, and, as I said, to make matters worse it kills my bike to ride it here.

        • #4 by Frans on 2010-10-23 - 07:14

          Wait, is that rear wheel or back wheel?

          • #5 by Ed on 2010-10-23 - 08:36

            There’s a difference between “rear” and “back”, as concerns wheels?

            You may substitute any other synonym for “back end of the bike” that you prefer…

            [grin]

          • #6 by Frans on 2010-10-23 - 08:45

            I was merely concerned that I may not have been using correct English terminology. The distinction between shade and shadow isn’t at all intuitive for a speaker of Dutch (or at least for me) either, since the shadow of a building is what provides the shade. In Dutch we only have one word, i.e. shadow, so you want to stand in the shadow to get out of the sun. But even if they’re both correct, one of the two might be unidiomatic, or marked as British, or some such. Trying to speak (Midwestern) American English can be tougher than you’d think when most people speak something like RP, or are at least trying to. ;)

            • #7 by Ed on 2010-10-23 - 09:51

              Heck, I have trouble speaking idiomatic English… whenever I try to figure out what I’m saying, I fall right over, just like the millipede trying to figure out how it manages to walk with all those legs.

              My esteemed wife tutors English-as-a-second-language and finds that the richness of American English can be completely baffling: we have many, many ways of saying not quite the same thing.

              On the other hand, given a bit of context, I’ve never had any trouble figuring out what somebody’s trying to say… apart from spammers who deliberately obfuscate their text.

              Rear, back, stern, aft, hindmost… that’s always the tire with the flat!

  2. #8 by peter on 2011-05-28 - 10:49

    Just wanted to say hi! Was searching the net for ideas on building a demagnetizing tool (like your design/idea with the shaded-pole motor- have a few lying about, must try that out too). Have just built a quick prototype from an old transformer that seems to work fine. Now to build it into a nice box with proper wiring and switches.

    BTW, am an avid ‘bent rider myself too, SWB though (Challenge Hurricane).

    That’s a nasty bit of wire in that tyre. Schwalbe Marathon Plus tyres are supposed to be nearly bomb-proof, even against that kind of stuff (even though I have my doubts), but too bad about their huge rolling resistance – no Marathon Plusses will make it on my bike ever again!

    Have used ordinary Marathons since about 3 years, and have switched to Marathon Racers this year. With the ordinary Marathons I only got one flat in 5000 kilometers, so far no flat yet with the Marathon Racers.

    Thought it funny that as I was reading your blog, we had many interests in common, but when the topic of recumbents came up I just had to reply.

    Greetings from yet another Dutchman!

    • #9 by Ed on 2011-05-28 - 11:38

      Now to build it into a nice box with proper wiring and switches.

      A work of art… and less likely to flatten you on the floor when your attention wanders!

      My resistance soldering gadget remains a breadboard: line-voltage components spread out across a wood plank. Every time I use the thing, I think I must put it in a box, but …

      supposed to be nearly bomb-proof, even against that kind of stuff

      I wish it were so!

      SWB though (Challenge Hurricane)

      You’re a faster cyclist than I, that’s for sure!

      Ride on…

    • #10 by Frans on 2011-05-28 - 15:54

      I’m afraid I’m not part of the recumbent crowd myself. I was only commenting on the tires as such. ;)

      • #11 by Ed on 2011-05-28 - 18:01

        not part of the recumbent crowd

        Oh, you’ll eventually come to your senses… [grin]

      • #12 by peter on 2011-06-08 - 17:36

        “A work of art… and less likely to flatten you on the floor when your attention wanders!”

        …. You haven’t seen my induction heater yet, have you? :-p

        After a hiatus of about a year I’m finally building it into a cabinet. I’ve temporarily unlocked a few photogalleries of the heater and some other projects: https://picasaweb.google.com/motorconversion

        And I’ll probably build another, larger demagnetizer soon, by modifying an old microwave-oven transformer. The projects keep getting added to the ‘to-do’ list faster than I can build them and strike them off that list.

        BTW, I am interested in learning more about your resistance soldering project. I played with resistance soldering it too, but couldn’t get it to work (transformer, using a carbon rod to transfer current to the workpiece). It was at the time when I was building the spotwelders that I experimented with resistance heating too, but in vain. So if you’ve succeeded where I have failed, then I’d love to learn more about your project :-)

        • #13 by Ed on 2011-06-08 - 19:32

          my induction heater

          Now that is a work of art, indeed: scares me just looking at it. Very nicely done!

          using a carbon rod to transfer current

          What made the resistance soldering gadget work was using a length of copper-coated gouging rod as the electrode. The copper burns off the bottom few mm, as that section gets yellow hot, but the remainder stays (relatively) cool. I’m not convinced there’s that much heating inside the joint, but having a that electrode pressed firmly to one side of the joint sure gets its attention in a hurry.

          You really do good work; I’m sure you can come up with something better than that

  3. #14 by peter on 2011-06-09 - 09:00

    Thanks for the response. I used a carbon rod out of an old battery and that didn’t seem to work. Will try the copper-coated gouging rod, should have a box of that laying about somewhere.

    If you ever do a blog write-up on your resistance soldering project, I’d be reading it with interest…. Hint, hint, nudge nudge :-p

    I mentioned the induction heater in my reply not because I considered it a work of art, but because for a long time it was used as your resistance heating project: various line-connected, high-voltage, high-current and hot parts laying about spread around on the desk. One wrong move and you’d either be burned or electrocuted. And connected to a scope floating at high voltage (isolation transformer was only big enough to power the scope, not the entire induction heater)….

    • #15 by Ed on 2011-06-09 - 09:31

      write-up on your resistance soldering project

      Some notes & asides start there, but I want to rebuild the triac triggering to be not so insanely complex (and, yeah, box it up). It’s been splayed out on the workbench for far too long already; all I need is a Round Tuit.

      Truth be known, right now I need a backhoe to clear some space on the workbench…

      • #16 by peter on 2011-06-09 - 11:12

        Very interesting project…. and yes, I was surprized by your way of driving the triac. But as you say, it’s not needed, fortunately. Which is a good thing, as I’m not good at programming microcontrollers.

        The funny thing is I may already have a resistance soldering unit without ever having realized it myself :-) Years ago I built a transformer spot welder (from a rewound microwave transformer) with NE555 timer that drives a solid-state relay. It never worked well as a spotwelder (there’s a few (8 or 16 milli-ohm; I forgot) resistance in the winding/connections, which ruins it as a spotwelder; 5V/.016 = 300 A max), it it had too little current capacity to spotweld even thin stainless steel:

        https://picasaweb.google.com/motorconversion/TransformerSpotwelder

        But it would be just perfect for a resistance soldering machine. Enough current for that, and a timer already built-in. I just need to build an electrode holder, it seems.

        I hadn’t realized yet one could even do brazing (hard soldering/silver soldering) with a resistance soldering unit. Very interesting. Unfortunately, the induction heater project has too little power (1kW) to heat mild steel enough for brazing, which was one of the reasons I wanted an IH. Above the Curie temperature of steel (about 750C), the effictiveness of an IH gets drastically reduced as the main mechanism of heating, the hysteresis losses, disappear, so I can’t heat steel much above 750C with my present IH.

        • #17 by Ed on 2011-06-09 - 12:10

          5V/.016 = 300 A max

          That’s about what this thing has, so I’d say you’re finished already.

          Bonus: it’s already in a box! (Sorta, kinda, close enough, would work for me)