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Thread: Seattube and chainstay questions

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    Default Seattube and chainstay questions

    Good Morning,

    I have tried to do my due diligence in finding an answer on my own first! ;)

    I am working on my second tig-welded frame.

    For the first I ordered tubing from Ceeway, purchasing a 28.6 externally butted Zona seat tube and 30/15mm chainstays, amongst the other tubes.

    I am going to try some different brands of tubing for my next several practice frames, just to get some practice in using different tubing types, and have been researching various types in preparation to order.

    My questions are:

    1) If tig welding, do I always need to use an externally butted seat tube? I don't have a lathe or mill to make any thicker tubing sections that I could weld into the top of the seat tube.

    2) I am going to be ordering some oval chainstay tubing blocks for my mitering jig and have the budget to get one set right now. I imagine that chainstay diameter is planned based on the weight of the rider and stiffness desired, however, If I was going to just use one size oval stay at this point what would be a good "middle-ground" size? For example, I see that Velospec for example, only offers 30x18, 30x16 and 26x17, whereas Reynolds offers 17.5x29 oval/round and 17x27 oval/round (perhaps with others sizes in higher end lines) and Dedacciai has 24mm and 22mm oval/round.

    3) Are round-oval-round chainstays primarily used for lugged bikes?

    Thank you in advance for you help!
    JD
     

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    Default Re: Seattube and chainstay questions

    JD,

    Thanks for stopping by the Salon...if you would, please place your full name in your signature line when posting in the FB section.

    As for your questions;

    1.) no, you are not relegated to using only externally butted seat tubes, in fact, in your early stages of learning, you will benefit by using thicker options. Mark at Paragon Machine works makes seat tube top inserts that can be pressed into a straight gauge tube and seam welded. This allows you to use any length of tubing you desire, increasing the versatility of your designs, and places a thicker section at the top where much of you heat input is. Critical to learning prior to good heat control, and a nice benefit as it is easy to use.

    2.) It appears to me that you are still investigating the hows and whys of tube selection...until you have a firmer grasp of the tube profiles you require for your intended use, I'd not drop money on dedicated fixturing. I'd encourage you to use some round tubing for your stays for the first frames. This will allow you to use more commonly available tube blocks (cheap), build some familiarity with how different size tubes translate to ride characteristics, and eventually, manipulate the round shape into ovals or detents for clearance. If you really want to begin using oval to round stays with dedicated fixtures, buy yourself a block of aluminum and get to carving it out; it will teach you more about metal work, coping, and fitment than buying someone else's work right now.

    3.) R-O-R stays can be used in many fabrication processes.

    Best of luck,

    Rody
    Last edited by Rody; 08-05-2019 at 03:16 PM.
    Rody Walter
    Groovy Cycleworks...Custom frames with a dash of Funk!
    Website - www.groovycycleworks.com
    Blog - www.groovycycleworks.blogspot.com
    Facebook - https://www.facebook.com/pages/Groov...s/227115749408

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    Default Re: Seattube and chainstay questions

    Morning Rody,

    I appreciate the time you took to reply. Your suggestions are quite helpful and a good reminder for me to focus on the metal working process, practice of basic skills and perhaps most importantly, repetition.

    Yes, I am in the early stages of learning how different tubing profiles, gauges, miters, butt-lengths, etc...all work separately and together to change ride characteristics for various rider weights, riding styles, etc...Its quite fun, and perhaps more knowledge on this will simply come from building and riding "practice" frames myself.

    I'll order some round chainstays and practice with these.

    Thanks again for the help Rody! Have a great day
    JD
    JD Reich

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