Wednesday, November 23, 2011

Lugged Bicycle Frame Construction in the Comfort of Your Own Shed

When modest fabrication skills meet lofty aspirations, the results are unknown

Oh no, what have I done?

Possibly, it has something to do with limom and all his ruminations on buying a frame. I have felt some of the same pulls, similar urges, as he as expressed, but I also have thought a lot about building my own frame. Not because I think I could do a fantastic job by just reading a book, or a better job than someone who actually knows what they are doing, no. I'm pretty certain I would be lucky if the first one was even usable. Or didn't fly apart while I was riding it and spear me with a not-very-well-mitred tube joint. Even the second one may just be OK. And by the time I would invest in the tools and parts to build two not very good brazed lugged JRA frames, paid the emergency room bills, and considering some discounted but still somewhat market rate for the hours I would spend, I would probably be able to just pick up a nicer frame built by someone who knows what they're doing. So there's certainly nothing very reasonable about the idea, at least not if you look at it like that.

However. On the other hand. I would be riding something unique, something that I knew very thoroughly, something that I made. I could probably build it with Dura-Ace 10 speed downtube shifters if I felt so inclined. If I completed the project at all. Or if it held together. I have only skimmed the book so far, intending to give it a good read-thru over the long weekend ahead, but, for example, if you don't get the silver brazing just right, the thing can just fall apart, wrecking not only you if you happen to be riding it when it breaks, but also any sort of paint job you may have put on it, too, since at a minimum the separated joint will have to be cleaned back down to bare metal and re-brazed. One option he mentions is to rattle can it, and then ride test it hard for a few months to see if it holds together, then getting the spray paint abrasive blasted off, and having a proper paint job done, once you're reasonably sure the brazes are holding. Or else, after you finish, have someone who knows what they're doing inspect the joints. Come to think of it, I do know someone I could check with while doing it, someone who does know what they're doing. Time to give him a call if I go forward, I think. Or look into a training course of some sort.

Another aspect of the project, though, is that I lack a good space for working on building a frame for dozens of hours, including mounting jigs for mitering tubes, as well as the brazing process itself. Hmm, it seems like I bought another DIY book a couple years back that would come in handy. Let's see, where did I put that book....

Yeah baby, bike-building shed, here I come!!!


  1. What have you gotten yourself into?
    Tube sets can be had for a couple of hunkies and the lugs for mebbe like a couple more.
    Four hundred and you can get started.
    Or at least look at the tubes while you build your shed.
    Hopefully next year I'll have a torch kit so I can practice a bit.
    Sort of gives the word frankenbike a whole new meaning.

  2. Seems like the hardest part of that might be building jigs to keep all the parts straight and square where they're supposed to be straight and square and not so straight and square where they're not supposed to be so straight and square.

    And justifying to the wife exactly why you should start such and endeavor.....

  3. There a couple of sites on the webz showing you how to build your own inexpensive jig using some extruded aluminium thingys.
    I was also thinking one of them hand held laser leveling things might be useful.
    I wonder, does this dude suggest using MAPP gas and silver solder?
    Or maybe oxy-MAPP?
    Should I order my lugs?

  4. Yep, the Chimonas book is based on MAPP and silver brazing (not solder). He does employ various combinations of bike stand and aluminum angle iron for positioning and alignment. His criteria for alignment is something like "rear wheel is centered between seat stays, and bike steers straight when ridden with no hands." He uses a non-laser protractor to check angles and also to align with horizontal or vertical. I'm still only partway through the book, but I've already gained more appreciation for the skill of frame building. And totally correct,, there would be some wicked negotiations up front to put a plan like this into place. Very optimistic about that part, anyway.

  5. Interesting.
    I used MAPP to work copper and from what I remember it took some time to hit temperature.
    I think oxy-MAPP is hotter.
    Silver is cooler working though and maybe the thinner gauge of the tubes will be faster.
    Have you checked out Henry James or Nova cycles yet?
    Also check out Velocipede Salon, lot of frame builders hang out over there.
    I been sort of looking into this semi seriously and it's the jig that worries me.
    Having this compulsion for perfection and all.
    I was thinking that instead of a jig, maybe you could get away with using three or four inexpensive bench vices mounted to a flat surface or frame.
    The jig is probably the deal maker/breaker for me.
    What do you think of the book?
    Should I get it?

  6. limom, with your MAPP experience it would probably be a piece of cake (tasty, chocolate, dark, rich) for you to pull silver brazing through lugs! I did take a look at Henry James and am still in the process of looking at other sites, thanks for the suggestions! Where I am so far reading the book, I'm getting slightly overwhelmed not so much by the basic brazing and clamping and measuring, which sounds like my cup of tea, but more by all the OTHER operations that are required on a frame--reaming, facing, chasing, and painting. What I gather so far from what I've read in the book is that the lugs themselves are the starting point for a lot of the alignment and setup, and the main focus is to work with the angles they provide. I like the book because he moves step by step with lots of photos and makes it all sound semi-feasible. Also a large project though. So a provisional YES get the book recommendation although subject to change once I actually finish reading it and possibly get started down the road of framebuilding. Or shed building. Or sleeping in my backyard with my stuff due to slight misunderstandings about the sense of building your own bicycle out of a pile of tubes and lugs.

  7. A lot depends on the standards you hold yourself to.
    I mean I've read where some folks are okay, "just getting" it and other folks need to "get it right."
    You sir, sound like a get it right sort of fellow so yes I suppose this could end up being a project of colossal and epic proportions.
    You know you could always sleep in the shed.
    Oh and my MAPP experience was limited to slapping some copper together to make something abstract.
    Not exactly bicycle science.
    If you know what I mean.
    Okay off to order that book and calculate just exactly what a project like this would set me back.
    Maybe I need to make more bowls.

  8. limom, I think I'll go and pick up a MAPP torch, some flux, brazing rod and some stock, and practice a bit, see how it flows.


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