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What diameter tubing for bmx build?

thefonz78thefonz78 Posts: 148
edited March 2013 in Workshop
I can not find any info on building a bmx frame. I plan on building frames for road tourers, off road and bmx. I can not find any info on frame thinkness on bmx's. I have the Reynolds tubing catalogue i'm not sure what diameters you would use for a bmx. Any ideas?

Posts

  • You sound as if you know what you are doing. I think the first step would be to measure the tubes in a bmx frame.

    Reynolds do not show people how to build frames because they are not framebuilders.

    And furthermore, Reynolds main tubes are all butted, and you may even find that BMX frames are made with pg tubes.
  • thefonz78thefonz78 Posts: 148
    No i no nothing. I've bee doing a bit of reading. I going to build a jig, then have a go at building some frames. Only a bit of fun i like a project. What is pg tubes?
  • softladsoftlad Posts: 3,587
    pg - plain gauge. Not sure I'd want to buy one of your frames, to be honest.....
  • thefonz78thefonz78 Posts: 148
    haha not going for sale just having a bit of fun
  • I think a good starting point would be to measure the tubes in an old bmx frame and then cut them up to get an idea of the wall thicknesses. You should also be able to just about tell whether bmx's are built with butted or plain gauge tubes.
  • keef66keef66 Posts: 13,286
    Get yourself on a framebuilding course and learn how to do it properly
  • thefonz78thefonz78 Posts: 148
    Yeah would love to. They all have 2 year waiting list's! Maybe get hold of some frame builders and see if the want a free dog body a few days a week in exchange for lessons. I can not find any builders in South Wales.
  • keef66keef66 Posts: 13,286
    Me too. Praps I'll put my name down for a course when I retire.
  • laelae Posts: 555
    You're gonna MIG weld 'em right, rather than braze them? For your first practice frames I'd start with cheap mild-steel tubing rather than anything fancy. Rather than paying a fiver a foot for chromoly stuff, it'll be more like a fiver for two metres.

    Someone I know has made frames (for a cruiser) using 40mm main tubes and 25mm chainstays. That's about right for a BMX. Wall thickness was 1.6mm - you could go up to 2mm or more, if you wanted more strength, but apparently a metre length of the 1.6mm stuff didn't flex if you stood on it. The downside is that it weighs a ton compared to chromoly, but it's a BMX, it's not supposed to be light!

    Once you've mastered the mechanics of framebuilding, then I'd move onto the expensive tubing. No point in spending 30 quid in materials to find out that your frame geometry is wrong!

    Sounds like a really interesting project, anyway. Let me know how it does!
  • You're gonna MIG weld 'em right, !

    Yes, practice with mig welding. But good quality tubes are Tig weldable only.
  • hounslowhounslow Posts: 153
    check fbmbmx.com, they do custom bmx frames, really nice ones. you may be able to get some advice out of them too.
    i would recommend asking on a bmx website, such as bikeguide.org as they are much more knowledgable on the subject, with some having quite a bit of experience on the subject.
  • keef66 wrote:
    Get yourself on a framebuilding course and learn how to do it properly


    You sir are a virgin
  • hounslow wrote:
    check fbmbmx.com, they do custom bmx frames, really nice ones. you may be able to get some advice out of them too.
    i would recommend asking on a bmx website, such as bikeguide.org as they are much more knowledgable on the subject, with some having quite a bit of experience on the subject.


    for a frame to be half decent it would be preffered to be TIG welded am at college now learning to tig
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