Lugged Bike Frame Update

Finally in the project’s end game. There is a very good chance this will be done on time.

The last of adhesive testing is done. My blend of epoxies is good for a shear strength of over 3000 psi. Given the smallest overlap is 2 inches, the weakest compressive/tensile link in the frame is 6000 pounds. I can deal with that.


The steel has all been fabricated, and while my carbon cures, I’m brazing it all up and cleaning it. The  head tube has finally been finished. Once the BB assembly is done, I can start epoxying the most critical structural component of the frame.


Now, I’ve been mostly very technical in my approach, but I have not forgotten that this is aesthetics of design. I have tested and very much like the finishing I’m going to be applying to the frame.

Oxide and flux caked head tube, fresh from brazing.
Head tube, post grind and wire brush.
Head tube, post grind and wire brush.
Post torch blue. Yes, my room is incandescently lit and has an orange floor. That is how it really looks. Brazing needs more practice and probably a new tip, but I’m stoked.

Right now, I’m rapidly cycling between total burn-out and being beyond excited about how this is shaping up. My angles look pretty dialed, and I have an assembly plan that should soak up any lingering geometric error. One vertex will be brazed last, so that I can use the actual positions of the intersecting tubes rather than mathematical predictions.

I’m beginning to doubt that I will present a complete bike, but anything is possible. My plan is to leave a day and half for the final clear coat to cure before I assemble.

My goal is:

Downtube and chainstays glued by 4/16

All steel and carbon fabbed by 4/17, EOD.

All carbon faced by 4/18, EOD

All steel (except top seat lug) finished, top tube glued by 4/19, EOD

Top seat lug finalized, 4/21

Top seat lug, seat stays, seat tube glued 4/22

Frame coated 4/23

Assembled morning of presentation, 4/25

Closest shave ever.




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4 Comments. Leave new

  • Andre Szlendak
    May 2, 2016 6:54 pm

    I absolutely love the brass finish of combining those lugs. Wonder how much material/cost it would take to cover the entire lug with that look. Though that might distract from the aesthetic that your’re trying to achieve. I’m impressed with how clever some of your jigging is, and the end result reflects that, with angle tolerances exceeding your expectations.

  • Mathew Tabor
    April 30, 2016 8:11 pm

    Matt’s right, you were never meant for EE, you need tools and metal. And fire. I still can’t believe all the analysis you are doing for this project; that in itself is enough for an entire independent study research…but hey, you’re making a bike so it’s well worth the effort. The brass brazing also adds a super cool look to the whole thing, gold errywhere. I was worried about putting together the actual bike pieces themselves, but after talking with you it sounds like you’ve got that part under control.

  • Jason Mcgrath
    April 17, 2016 8:47 pm

    Enjoyed reading this post. Echoing the comment above, Seems like you have several different processes going that the project hinges on. Very ambitious! Do you have a some kind of visualization of what the end result should look like? (Maybe in a former post I have read?) I’m curious to see where this is heading because from the description above, it sounds like a high performance machine. I appreciate seeing a real product in the works!

  • Matthew Sturm
    April 16, 2016 1:04 pm

    Hey buddy this is really good stuff. Why did you do your undergrad in EE again? Mechanical was calling the whole time!
    Something I’ve thought after seeing your blogs is that all of your materials testing could be turned into some cool learning tutorials. Maybe you could get the ITLL to pay you to develop some simple workshop on instron testing and/or carbon layups?


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