Second (kinda first really) frame questions- Mtbr.com
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  1. #1
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    Second (kinda first really) frame questions

    Hi
    I've been lurking on here for a while. I'm just about to embark on my first real build. I fillet brazed a a frame on a course about 3 months ago. I've finally accumulated the various tooling and built my jig and pretty much good to go. The only difference being i have opted for TIG as OA scares me and i'm pretty limited space wise, so two big bottles seemed like a no go.
    Ive been practising a bunch with the tig welding and i feel like i'm in a good place, although i still have a few kinks to iron out. I still feel like i'm getting things a bit too hot. But i reckon i just gotta get more time under the hood.

    Anyways, i have a few questions about tubing selection and places to source it in the uk.
    I have seen a few people mention kits, the main supplier in the uk sells some kits. But the seem to all be oriented towards lugged construction. I assume i cant use these tubes for tig?

    Im aiming to build a sscx frame, cantis, reasonable clearance etc. So weight isn't hugely important, really i'm just wanting to get another frame out, and develop the skill set. I don't expect to have a perfect frame/second first attempt.

    Could anyone point me in the right direction for a sensible tubing set, or some things to keep my eye out for when it comes to wall thickness and whatnot?

    thanks
    Max

  2. #2
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  3. #3
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    yeah i was looking through their site, their framekits seem good but i wasnt sure if the trubing in their framekits was the right choice of my first tig build.

    Top Tube 28.6 x 600 x 0.9/0.6/0.9mm
    Down Tube 31.7 x 640 x 0.9/0.6/0.9mm
    Seat Tube 28.6 x 700 x 0.9/0.6mm
    Chain Stays 22.2 x 420 x 0.8mm
    Seat Stays 16mm x 560 x 0.8mm
    Head Tube 31.7 x 650 x 1mm

    i think at the moment the tubing i have been practising with is about 1mm wall thickness. Is this gonna be a huge departure in terms of feel/difficulty?

  4. #4
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    Can't help you with a supplier because I'm on the opposite side of the world, but I believe Ceeway should be forthcoming with some advise.
    The DT is way too short by the way if you're building a 29" frame, and I suggest that because you need to use longer DT's that you go up to 35mm minimum.

    Ceeway do Columbus tubing so you should be able to put together a suitable MTB set-up.

    You don't specify what sort of bike you are building, might be a better way to phrase your question.

    The Seat Tube would be better using an External Butt type for Tig Welding.

    Keep talking, give us more detail.

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

  5. #5
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    thanks for the info, sorry i haven't really figured out how the comment threads work on this site. Im not sure if other people can see the original post or just me. But i went into a bit more detail in terms of what im looking to build.

    long story short i was looking to build an sscx frame. hopefully large ish tyre cap at 700c, 2*canti/vbrakes, relaxed geo and singlespeed/fixed

    thanks for the help
    max

  6. #6
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    0.9mm is about as thick as you're going to get for bicycle specific tubing with the exception the top butt of a seat tube and some Variwall tubing. 0.8 is probably on the thin side for you. However, Columbus doesn't make much in the way of thicker tubes.

    You may have trouble finding a tube set that meets your needs. This one from Nova probably comes close with the oval and bent stays: https://www.cycle-frames.com/bicycle...SEATSTAYS.html I'd potentially up the downtube to 35mm depending on how big you are.

    If you want to source something like that on your side of the pond, you may just need to pick individual tubes. I'm guessing you have a domestic supplier of Reynolds, but I don't know who that is.
    I make bikes. www.feldybikes.com

  7. #7
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    oh nice thanks, that seems like a good bet. yeah i just gotta find somewhere in the uk, i have dropped an email to a uk based supplier so ill see what they say.

    Im feeling decent with tig at the moment, i pretty sure i can lay decent beads on 0.9mm with a bit more practice.

    Im not that heavy, around 68-70kg (150/160 #)so would the dt dia affecting the rigidity of the frame under load? At what weight bracket does that become a major issue?

    Im not wholly against buying tubes individually, the initial intimidation i felt when i started looking at tubes is starting to fade. Iill have a poke around and see what i can find nearby, or at least int he uk.


    thanks for replying
    max

  8. #8
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    At your size I'd say your fine with whatever size downtube floats your boat aesthetically. Another 5 or 10 kilos and I'd go with the bigger size. But even then, if someone wanted to go with a skinnier downtube I wouldn't just outright say they're wrong.
    I make bikes. www.feldybikes.com

  9. #9
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    OK. Defined.
    Frame Design: Short Wheelbase CX if riding tight technical routes. The DT you have on list will be fine at 640mm. If you are looking at mostly straight or flowy routes of mixed surfaces I would suggest going Geo-Forward in your approach. The stability you will get is worth the effort. Set the Head Tube Angle at 70-71 degrees and a trail range between 70-82mm and you will have a rewarding ride. Not twitchy, but will cover the ground very quickly.
    Tube selection that you have listed will work fine. Just note my earlier comment on the Seat Tube. Having a 1.0 to 1.2mm wall thickness at the top of the Seat Tube allows for a much better joint. And some extra thickness to ream out if neccessary.

    Happy hunting for your tubing. Initially, buying individual tubes may seem daunting, but you won't really make a big mistake with where you are going with this build.

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

  10. #10
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    awesome thanks Eric that's super helpful.

    Right i better get on with it then!

    Thanks for the help guys.
    Max

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