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  1. #1
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    XXL Frame - Tubing Thoughts

    I've done some forum searching, but I haven't come up with much info that's applicable.

    I'm a hobby-builder (building for myself only). Nothing fancy; hacksaws, files, and a drill press, fillet brazed 4130 frames, homemade 80/20 fixtures.

    I'm starting to plan my 4th frame. The first 3 were a fat bike, a mid-length cargo bike, and a 27.5 Plus MTB.

    For the first 3 frames I used these non-heat treated 4130 tubes:
    • DT: either 34.9 or 38.1, .9/.6/.9
    • TT: 31.8, .9/.6/.9
    • ST: either 28.6 or 31.8, .9 straight gauge, sleeved at seat cluster


    Thing is, I'm 6'7" and 230lbs, and I like longer head tubes and relatively horizontal top tubes. All my frames have had (and will have) really big front triangles with eff TT lengths around 660mm, ST lengths in the 590-610 range (c-c) and 185-200mm head tubes.

    Frame #4 is another fat bike, and I was planning to use these non-heat treated 4130 tubes:
    • .9/.6/.9 for the 38.1 DT
    • .9/.6/.9 for the 31.8 TT
    • .9 SG for the 31.8 ST (sleeved to 34.9 at ST cluster).


    But now I'm second guessing myself... for my height, weight and frame size, should I also be using .9 straight gauge for the DT and TT?

    Interested in what more experienced builders think...

    Thanks!

  2. #2
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    Look at Vari-Wall's offerings like this: https://shop.vari-wall.com/Steel-Tub...81171s-285-02/
    Or find some True Temper Supertherm 1.1/.7/1.1
    NOTHING WORKS LIKE CLOCKWORK

    www.clockworkbikes.com

  3. #3
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    Quote Originally Posted by Clockwork Bikes View Post
    Look at Vari-Wall's offerings like this: https://shop.vari-wall.com/Steel-Tub...81171s-285-02/
    Or find some True Temper Supertherm 1.1/.7/1.1
    Thanks Joel. I've stayed away from heat treated tubes since I'm doing everything by hand (files and hacksaw). How is the Thermlx to work with?

  4. #4
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    It's not bad at all. You just want to avoid the super hard stuff like XCr or 953.
    NOTHING WORKS LIKE CLOCKWORK

    www.clockworkbikes.com

  5. #5
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    Straightgauge won't be any stronger - you're not going to break the tubes in the thin/middle sections anyway.

    If you're not a crazy hucker, and your existing bikes are holding up, you could certainly stick with what you have done before.

    If I were building you a frame, I'd use Vari-Wall tubes like Joel mentioned in 1mm wall thickness. But I'm paranoid (and building stuff for people who aren't me). You're probably fine to keep doing what you've been doing.

    -Walt

  6. #6
    dru
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    You'd mentioned files and a hack saw. Do you own a Dremel? I've built two frames using OX Platinum and the Dremel is a godsend. A junior hacksaw cuts just fine btw. I needed to do a bit of filing on the brass but nothing on the miters. A Dremel does amazing things.
    occasional cyclist

  7. #7
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    Quote Originally Posted by dru View Post
    You'd mentioned files and a hack saw. Do you own a Dremel? I've built two frames using OX Platinum and the Dremel is a godsend. A junior hacksaw cuts just fine btw. I needed to do a bit of filing on the brass but nothing on the miters. A Dremel does amazing things.
    Curious what bits you used for doing the miters...
    Last edited by PC56; 09-29-2018 at 03:57 AM. Reason: Add quote

  8. #8
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    Thanks Joel and Walt for the advice. Really appreciate it.

  9. #9
    dru
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    I don't use any bits on the Dremel. The rough miter is cut by hand with cheap generic relatively close spaced hack saw blades. I also use a junior hack saw. I finish the miters with the various sanding drums for the Dremel. Usually the biggest one is best. These drums go through the metal like a hot knife through butter.
    Attached Thumbnails Attached Thumbnails XXL Frame - Tubing Thoughts-dremel-makes-quick-work.jpg  

    occasional cyclist

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