Weight weenie dream tourer

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  • Is there such a thing as a catback tandem?

  • Those are some terrific ideas- thank you very much. Never heard of carbon tow, but it looks ideal.

    As for tube width, I'm tempted to start with 2mm rod, if only for the excitement. Doesn't matter if the prototype breaks. And imagine a rack made of bits which are so thin that you can hardly see them!

    I'm already mentally committed to triangles. Barnes Wallis is my inspiration. Getting compression will be a challenge. I'm no good at conceiving a design in my head. Didn't even pass Physics O level. So it'll be trial and error. I thought I might start by making something out of dowel.

  • This project is great- it's different and kinda extreme but also really fun. Keep it up!

  • Does anyone know about video camera settings for Youtube? I've got a Gopro 9 and have made some fat files which my PC isn't powerful enough to play smoothly. They're 2.7k resolution and 60 fps. I think they're HEVC. Plus there are Protune settings which I know nothing about. I'm now using Any Video Converter in an attempt to make them playable on my PC without ruining the quality.

  • Mpv may help you to play it back more smoothly, otherwise try setting your GoPro to 1920x1080 at 30 FPS.


  • It doesn't install. And the page about installation seems to be aimed at techies. https://mpv.io/installation/ But I went here anyway https://sourceforge.net/projects/mpv-pla­yer-windows/files/ , clicked on Download Latest Version and got a file called bootstrapper.zip, which opened a very scary multicolour window with a command line. No thanks. I rate this the worst technical help I've been given for a long time.

  • Mpv.net that I linked is the user friendly version of mpv, which is what you found ... You could try VLC which is a popular alternative

  • Never mind. AVC has converted the files with acceptable quality and now Shotcut can play them without stuttering.

  • handbrake is very good for converting video files

  • You're probably better off recording at a lower resolution, it will be a lot easier to edit and should save some battery on the GoPro too

  • Indeed. Smaller files will make life much easier.

  • Where is that museum? Is it the one near Coventry?

  • I've not been, but wiki says it's the Brooklands Museum https://en.wikipedia.org/wiki/Brooklands­_Museum

  • This thread is DBAD x Fixed Super Light Super Safe.

  • I had a look at that thread and it did my head in. It goes on and on and on and it's all about buying new. What a stupid idea.

  • A rack made of 2mm tubes is way more sensible

  • Carbon chainrings on a tourer hahaha

    I'll have you know I did that years ago.

    The steel Robin Mather started with Clavicula cranks... https://photos.app.goo.gl/GzNoGirNS25PN9­5QA

    Then I learned they creak like a well lived-in bed and sold them on to replace them with an alu crankset ( https://www.peterwhitecycles.com/carmina­.php ) that hasn't needed a bit of maintenance and a new BB ( https://www.renehersecycles.com/shop/com­ponents/bottom-brackets/skf-bottom-brack­et-iso-square-taper/ ) that is totally silent and smooth. Not as light, but a far nicer ride.

    Also... this thread is genius. I love it, and as I'm becoming a cat father in only a month or so I am subscribing because this is right up my street and precisely the kind of thing I would, and probably will, do.

    (my Robin Mather bike is basically cat ready if I get a custom bag made for the front)

  • I'll have you know I did that years ago.

    I've done lots of things in my younger years that were not good ideas :)
    That's how you gain wisdom (and lose teeth).

  • my Robin Mather bike is basically cat ready

    What a beauty! It's not just cat ready, it's cat plus dog ready, even if they fight. You really need to get it inhabited asap. Doesn't have to be a dog. Many other creatures would enjoy the ride. Here's an inspirational film. Pick any two species from three.


  • I don't want to be one of those naysayers (this whole thing is bonkers and I love your attitude towards this), but 2-3 mm tent poles in carbon might be awful.

    Off the top of my head tent poles tend to be in the 10+ mm region. Stiffness scales a lot with diameter, so a 2 mm pole is going to be orders of magnitude less stiff than a more standard size

  • But I'm talking rods, not poles. And as you can see from the tent, stiffness has to balanced with bendiness. The pockets hold the poles in compression. Even 1mm rods would probably hold up the tent fabric, especially if I copy the tent with lighter fabric. Not sure what would happen if it's windy though.

    I think part of the reason why the original poles for my tent are so wide is to reduce warranty claims when people break them with clumsy handling and packing. It's a similar story with many products - they have to be overengineered to keep the return rate low. But if you make something yourself you rather expect it to break (well, I do) so you just mend it and carry on. I tried to be clever by checking the numbers for the Young's modulus at easycomposites but they seem to be identical for every product. Obviously I have no idea what they mean, so I'll just pretend they don't matter.

    The rack is a different thing. I have no idea about it really. It's 100% experimental. Whatever I make will have to be tested to destruction by using it for supermarket shopping well before I decide the final spec.

  • Perhaps someone with composite experience can weigh in. @Jonny69 perhaps.
    The tailfin rear rack looks something like 20mm diameter and has a 18kg rating. I can't see how 2mm rod won't snap under anything other than a very minor load

  • The Young's Modulus is a property of the carbon fibre composite itself, not the specific tube. Each material has a Young's Modulus. It's just a measure of how stiff that material is.

    "Tensile strength" is the most useful stat to pay attention to.

  • @PhilDAS

    It's perhaps easiest to compare with an aluminum rack. Alu has a similar tensile strength to carbon when dimensions are the same (but the alu will be heavier).

    So imagine the thinnest struts on an aluminum rack that you could use for lightweight touring. Roughly 7mm OD with 1mm wall thickness? That's likely also as thin as you can go with carbon. Well you know... +/- 20% because of grade/imperfections/tolerances.

    2mm carbon tube (0.5mm wall thickness) weighs 3.6g/m. Three grams per metre. It's gonna snap.

    7mm carbon tube (1mm wall thickness) weighs 30g/m. You'll need something like 3 metres of tube, so 90g of carbon. Other hardware/fittings/glue will add maybe 100g? A 200g rack is a hell of an achievement.

  • There are a couple of mistakes on that table:
    1) Young's modulus unit should be GPa. Figures given for Al and Ti64 look about correct. For woven carbon it will be between 50-110 GPa. UD will be 150-300 GPa depending on the fibre.
    2) Unit for strength should be in MPa. N/m^2 is valid for strength, but the figures given are not in N/m^2, they're in MPa. There's no yield strength for carbon as it doesn't yield and draw like a metal.
    3) Tensile strength (UTS) figures given there for carbon are not correct. For woven carbon you'd expect to see 600 MPa for the lowest strength fibres up to about 1600 MPa for the strongest fibres. The range for UD will be 1600 MPa up to about 3700 MPa depending on the fibre and resin.
    4) Density figures are not correct there. In kg/m^3 it would be 2700 for Al, 4400 for Ti64, and 1800 for carbon. Carbon is significantly lower density than common metals.

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Weight weenie dream tourer

Posted by Avatar for nick_h. @nick_h.