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  1. #1
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    Advice on TrueTemper tubing thickness

    First off I wanted to say thank you to all the folks who contribute to this forum. A huge thanks to Walt! It's really helped me out! I've been lurking here for a long time.

    I'm designing a trail bike for myself, I weigh 135lbs but I'm fairly aggressive and I tend to look for things to pop off of and hit. Most of the terrain I ride is very rocky. I'm wondering if TT HOXPLAT 8/5/8 tubing would feel a little thin for a DT. Do most of you go with a 9/6/9 TT VHT type of tubing for more agressive trail bikes? I'm also concerned that the 34.9 1.6/.8 seat tube might be a bit weak at the bottom. Should I SuperTherm that and make it bomber? I want something strong but I don't want to overkill it for my weight.

    Thanks so much for any advice you can give me. Much appreciated.

    Collin

  2. #2
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    Just go Supertherm everywhere and then you don't have to worry about it. The extra half pound of tubing will never be noticeable even for a skinny guy.

    I definitely would not use 8/5/8. That's for road bikes and light-duty XC. 9/6/9 HT stuff would work fine (ie the HOX2DT01 downtube) but if it were my bike I'd probably just do Supertherm.

    -Walt
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  3. #3
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    Thanks Walt! I figured the 8/5/8 was a bit thin.

    It's funny I see so many mtn bikes boasting TT ox plat tubing. My guess is there is maybe one tube that is ox plat and the rest is who knows what or they are just a bit weak.

  4. #4
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    I guess Supertherm is thick ox plat though, so that makes sense.

  5. #5
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    Remember - most of the bigger companies have tubes drawn specifically for them. What you see in the Henry James catalog is mostly not what is being used on, say, a Niner.

    -Walt
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  6. #6
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    Ahh, very true. Didn't think of that. Thanks again!

  7. #7
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    Not to confuse the issue, but a full Supertherm frame for a guy that weighs a buck-35 sounds like overkill for anything short of a full on DH frame. I'd use an non heat treated 9/6/9 (depending on diameter) for the down tube unless you're planning on running a really long fork. If you haven't built many (or any) frames, I'd also steer you away from heat treated tubing.
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  8. #8
    650b me
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    What's the issue with heat-treated tubing?

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    Quote Originally Posted by golden boy View Post
    What's the issue with heat-treated tubing?
    Can be a bit more "exciting" to miter, and lower economic tolerance to screw-ups.

  10. #10
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    Exciting?

    Not sure what you mean by that, but I just cut my first OX Platinum tube with a hacksaw. I used the 24tpi blade that came with my Stanley FatMax, knowing that when it wore out I would probably be looking at an "upgrade" blade. Well, one cut on that OX Platinum and the blade is toast. Missing about 1/4 of its teeth. Lesson learned. Is that what you mean by "exciting?"

  11. #11
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    Quote Originally Posted by Walt View Post
    I definitely would not use 8/5/8. That's for road bikes and light-duty XC. 9/6/9 HT stuff would work fine (ie the HOX2DT01 downtube) but if it were my bike I'd probably just do Supertherm.

    -Walt
    Curious, Walt: what percentage of your mountain bike frames do you build with 8/5/8? I used 8/5/8 for the top and down tubes on my UBI frame. I was going to use 9/6/9, but my frame design and their tube stock dictated that I use 8/5/8. The frame feels great to me, stiff enough but definitely comfy, like there's just a bit of flex going on. I ride XC-Trail-ish trails, typical Front Range/Jeffco trails mostly. Should I not expect much longevity in this frame? I strive for smoothness in my riding style, and I never break $hit, so I hadn't given it much thought until now.

  12. #12
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    Quote Originally Posted by golden boy View Post
    What's the issue with heat-treated tubing?
    The problem with heat treated tubing for beginners is two fold. First it can't be cold set much so uneven rookie brazing can not be corrected by bending it back into alignment. Also heat treated tubing is more common in the thinner wall thicknesses (for example .7/.4/.7) and this light tubing also requires more torch skill that a person starting out is likely to have. For these reasons I don't let students use light heat treated tubing in my framebuilding classes. They need to begin with materials that will give them immediate success and provide a solid foundation for their future efforts.

    The general rule for the number of saw teeth required for any situation is to have at least 2 on the work at all times. For almost all purposes a 32 tooth hacksaw blade is required to cut thin wall tubing. Or, as you found out, they chip when the teeth drops into the edge of the tube and continues to be pushed.

  13. #13
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    Quote Originally Posted by golden boy View Post
    Exciting?

    Not sure what you mean by that, but I just cut my first OX Platinum tube with a hacksaw. I used the 24tpi blade that came with my Stanley FatMax, knowing that when it wore out I would probably be looking at an "upgrade" blade. Well, one cut on that OX Platinum and the blade is toast. Missing about 1/4 of its teeth. Lesson learned. Is that what you mean by "exciting?"
    Yeah, like that, but with a lot more horsepower behind it!

  14. #14
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    Advice on TrueTemper tubing thickness

    I don't know your skill level but if this is your first or second frame I would order the Nova 9/6/9 tubeset and go straight gauge for the seat tube. Sleeve or collar some 4130 and don't waste the money and time cutting filing & reaming OX plat.

    Walt or Rody have the most experience here but 9/6/9 is plenty strong in my (albeit limited) experience for riding hard but with 30+ lbs on you. I'm riding an 8/5/8 front triangle and it's too noodly for my liking.

    If it were for my bike and I rode like you (i weigh 165lbs) i would use maybe a supertherm 35mm DT if you're really crazy and have a 140mm fork up front, 4130 0.035 wall collared ST, 8/5/8 31.8 OX Plat top tube, a Paragon head tube, Deda chainstays and some 4130 5/8" seatstays.

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    Collin

    Not to confuse you on tube size but to ask you a practical question that may shed clarity to your question. At 135lbs, if you are tall, you are riding a larger triangled frame. I suspect you may be shorter in stature and use a smaller front triangle, as such, your ability to load a frame is less, and with a smaller triangle, you have a stronger structure as the tubes are shorter. You would in this case ask a fair question regarding wall thickness. We don't have enough info to say for sure.

    Opps, missed the seat-tube question - 34.9mm is big, and strong. Substantially more than usual 28.6mm so at the BB, the shorter butt is not as bad as it may initially appear.

    Eric
    If I don't make an attempt, how will I know if it will work?

  16. #16
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    Thanks everyone! This is super helpful. This will only be my second frame and I have never worked with anything heat treated. So things might get exciting. The bike will have a 140mm fork on the front and I'm only 5'8, so the front triangle will be pretty compact but with a 140mm fork and 650b wheel its gonna get some strain on it. It will also be fillet brazed. I like the idea of sticking with cheaper, simpler steel while I gain experience.

    Thanks again everyone!

  17. #17
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    Good luck, Collin. I'm on frame #2 as well. Sorry for the attempted hijacking.

  18. #18
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    Quote Originally Posted by golden boy View Post
    What's the issue with heat-treated tubing?
    All the reasons stated by others. It's harder to work with, it's expensive (relative to non-HT tubes) but most of all, it can't easily be corrected by a fingy if it's not straight. It's like this, as the window between yield strength and ultimate tensile strength narrows, the elongation/ductility decreases. In the real world this means that you have a very narrow margin of safety between being able to successfully cold set a frame made of heat treated tubes and ruining it. Other than that, heat treated tubes are generally only of value in really lightweight tubesets. Supertherm is popular simply because there are so few other tubes available with such thick butts.
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  19. #19
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    Quote Originally Posted by DWF View Post
    there are so few other tubes available with such thick butts.

    I like thick butts and I can not lie

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    I guess it also comes down to how good of a welder you are. Too thin of a tube, regardless of the fact that it's HT or not, and you increase your chances of blowing holes thru, this is considering your notches are perfect too.

    My first idea was also to use the 34.9 seat tube on the two frames i'm building right now. When I had them in my hands I decided not to use them because they are too heavy... Sure looks bulletoproof though.

  21. #21
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    Quote Originally Posted by Meriwether View Post
    Walt or Rody have the most experience here but 9/6/9 is plenty strong in my (albeit limited) experience for riding hard but with 30+ lbs on you. I'm riding an 8/5/8 front triangle and it's too noodly for my liking.

    If it were for my bike and I rode like you (i weigh 165lbs)...
    I'm 165 and riding an 8/5/8 front triangle and I just think it feels really good and comfortable. Of course ride feel is very subjective.

  22. #22
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    Quote Originally Posted by golden boy View Post
    I'm 165 and riding an 8/5/8 front triangle and I just think it feels really good and comfortable. Of course ride feel is very subjective.
    I like it overall but it seems to me that it twists on hard front-end hits more than I like. It happens when I ride it rigid and with suspension. I'm only using a Fox F29 without a 15QR or tapered steerer so it may somewhat related to that. I'm more worried about the 0.5mm wall on the majority of the downtube. Maybe it's just in my head but hearing Walt say he wouldn't use it on an MTB will make me think twice before using it again as a downtube for a MTB frame that'll be ridden really hard.

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