Archive for the ‘Lugs’ Category

Which Road: Easy or True

Monday, December 14th, 2009

Shaking Up the Collaborative To Challenge Our Assumptions

Lots of iterations of design

Lots of iterations of design

Someone asked a question regarding why the Collaborative is trying to work with lugs when it seems pretty clear that off-the-shelf options aren’t working for this project.  Or at least, preexisting lugs didn’t work for the Seven Cycles Shop Bike we just built.

Answering this question quickly becomes a circular discussion.  In the context of the Collaborative, an example might look something like this.  In fact, In order to explain one of the reasons why we’re committed to using lugs, and simultaneously frustrated by using lugs, I’ll provide a real world example.

But first, remember that one of the elements of the Collab’s mission is to work with lugs.  I’ve provided some of the compelling reasons we’re dedicated to lugs for this project—and I’ll be providing more reasons in the coming weeks.

On To the Example


Bicycle Frame Lug Types

Sunday, December 13th, 2009
Evaluating a few lug methods

Evaluating a few lug methods

Early in the Seven Cycles Collaborative we discussed the ways in which we could go about sourcing or making lugs.  Here are a few of the ways to make bicycle frame lugs:

  • Investment casting:  This is the most common method of making high quality lugs.  This is the oldest form of metal forming on the planet.  It’s a pretty amazing way of making a formed part.
  • Stamped from sheet:  This is the lease expensive way to make lugs in large quantities.
  • Bulge forming:  This has only been used a few times, relatively speaking, compared to other methods.  Basically, a steel tube is put into a lugged shaped mold and hydrostatic pressure is used to expand and shape the tube into a lugged form.
  • Welding or brazing tubes together:  This is the method that Seven Cycles is using for the Collaborative Shop Bike.  Photos to follow.  This is also the method that Seven uses on our titanium and carbon mix frames.
  • Machined:  This is not something I’m aware of for steel frames but some other lugged construction frames start with a molded part and then final machine the angles and details.  I include this on the list because it’s one of the ways that we are evaluating making lugs for the Collaborative.  However, it would be more appropriate for a production setting, not so much for the Colab project.
  • Combination:  This is very common, particularly among artisan frame builder.  Combo lugs take an investment casting and the add material, or more commonly, remove material to end up with a different look and characteristic than a raw casting.

We discussed a few other ways to make lugs but we’re keeping those ideas under wraps for the moment.

Lots of options; all with challenges.  More later.

Quotable #12

Tuesday, December 8th, 2009
Bracing for the storm

Bracing for the storm

An addendum to the “Lug Options” post:

Here’s one of my favorite quotes from the Seven Cycles Collaborative so far.  It’s from Bryan Hollingsworth. He’s managing the lug design portion of the Colab.  So, yesterday when he was he was sharing the lug search results for our Shop Bike test, here’s what he said about our available options:

“It’s a perfect storm of nothing.”Bryan Hollingsworth

If you read the previous post—Lug Options—this statement sums it up perfectly.  I just had to share it.

Lug Options

Tuesday, December 8th, 2009
Lugs, lugs everywhere and not a one to drink

Lugs, lugs everywhere and not a one to drink

So, we’re collecting all the parts required to build our first test-of-concept frame:  the Seven Cycles Shop Bike I mentioned last week.  Our intention was to source the four lugs and maybe build one from scratch; making a lug from scratch was to be part of our conceptual test.  Well, it turns out that we can’t find a single lug that will work on this shop bike—not even one.


We’ve looked at too many lug sources—through suppliers and direct from manufacturers, domestic and overseas, road and mountain, high quality and cheap—and cannot find a single lug that will work on any of the four joints that would typically get lugs.  “What the what?” This bike design is completely within Seven’s norms.  In fact, we tried to design the geometry so that we could use some standard lugs.  Still, no dice.

I’m sad to say that this is one of the more enlightening moments of the project for me—and for many others in the Collaborative.  Here we are trying to design a bike—a fairly average bike design, by Seven’s standards—and we can’t find a single lug that will work.


Brazing Clinic

Tuesday, November 24th, 2009
Brazing the first lug at the clinic

Brazing the first lug at the clinic

This evening we had our brazing clinic at Seven Cycles.  I have video that I’m trying to get posted but it’s being a drag.  So, just a couple photos for now.

During the meeting we reviewed some of the elements on which we’re focusing—see the previous post—and then we watched Yoshi Nishikawa braze a frame joint.  Yoshi’s done a lot of lugged steel brazing over the years so he was a good person to watch.  And Tim Delaney was the commentator—with 30 years of brazing under his belt—so he was perfect for explaining what was going on.  There was a lot going on during brazing so it was impossible to cover all the bases in one clinic.

Throughout the Collaborative it’s been fun to have this large group of people with very different backgrounds.  A great example of this diversity was in the brazing clinic.  We had lots of questions, ranging from, “Why would we use one brazing alloy over another alloy?” to, “What’s flux?” We’ll try to answer those questions at some point.

Explaining how the process works is possible in a few short words.  At a very high level, here are the steps:


Lug Testing Research

Sunday, November 22nd, 2009
Lots of interesting lugged construction articles--from the 80s.

Lots of interesting lugged construction articles--from the 80s.

I’ve been digging through all my old articles and periodicals for anything that relates to lugged frame construction.   It’s been a while since I read through it all.   Some of the best data I’ve been able to find is from the late 1980s.   Some of the other Colabbers are digging up old articles, too.

In the 100+ pages of reading I haven’t found any good fatigue testing data for lugged steel frame construction.  We’re not done searching but I’m starting to have doubts.  If you’ve seen any, let me know.


Initial Lugs Arrived

Wednesday, November 18th, 2009
Henry James lugs loitering.

Henry James lugs loitering.

Here are our first test lugs.  They just arrived from Henry James.  A great person and company; Seven Cycles has worked with him and his wife for many years.

These are the first “strange” parts we’re working with in the Collaborative.   I say strange because lugs are the only element of a frame that we don’t work with on a daily basis; we work with steel everyday; we work with brazing everyday; we work with fatigue testing everyday; you get the idea.  Lugs, not so much.  Aside from employees’ personal projects, lugs are a rare find in the shop.

Next Step

Now we’re going to start melting metal and making parts to break.  The fun begins.  I expect we’ll have something to show tomorrow.

Ever the optimist.  – RV

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