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  1. #1
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    Head Tube Question

    Hi - I'm working on my first frame, standard lugged road bike, and bought straight gauge tubing from an aircraft supply shop. The head tube I bought is 1 1/4" with 0.035 wall, which I now realize is slightly thinner than the bike specific head tubes that Nova is selling. Will it work or should I get a new one?

    Thanks!

  2. #2
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    It will probably work

    The nova headtubes are usually 1.1mm wall thickness and the one you got is around 0.9mm. For lugged frame your headtube will probably work because the stressed parts of the headtube will be reinforced by the lug. Keep in mind that to make room for headset cups, the very ends of a 1.1mm headtube get reamed and thinned anyway.

    I am assuming your tube in question is CrMo and not mild steel. If your tube is CrMo you should be okay. KVA, which is martensitic stainless tube set, usually includes a 304 series stainless steel headtube (not martensitic steel) which is I think 0.9mm or 0.7mm in wall thickness. Compared to CrMo, 304 series has a higher tensile strength but is more brittle (less tough and more prone to fracture). So, with these parameters in mind, I think your 0.9mm wall thickness CrMo headtube will do fine for a lugged frame provided penetration of your filler alloy during brazing is complete.

  3. #3
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    Ok, great, thank you! I am using CrMo. Thanks for the help!

  4. #4
    Nemophilist
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    Hey;

    I would tend to agree with mchimonas, from a theoretical standpoint (I don't have such direct experience, yet). I would add that choices like these are very use and user specific. This choice for your lugged road frame? Likely OK, given good brazing skills, of course. For a big rider? Perhaps, but you might consider sweating on an upper and lower reinforcing ring to strengthen the cup areas. For a TIG welded frame? Wouldn't make me comfortable.

    General feeling; Anything around the front end makes me nervous. I'd rather make it needlessly stout than wind up spitting teeth.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  5. #5
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    .9mm is normal.

    31.8 x .9mm 4130 is the most commonly used size for lugged frame 1" head tubes, it will work just fine.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  6. #6
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    Thanks everyone! Got the front triangle together yesterday!

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