Apologies to Joe B-Z and Andrew Gillis and any others with these lugs, my words were badly chosen and incomplete. What I should have said is the maybe five frames (definitely under 10) I have seen crack there (out of hundreds of such frames?) makes the rate a little higher than the incidence I would have expected, had the lugs not been trimmed back so far.
I did NOT mean that all or most of the frames made with this type of lug would crack. No matter what the rider weight, most will probably last, in practical terms, forever.
One guy who I know cracked his Ohtsuya-lugged frame at the headtube was a 40,000 mile-a-year RAAM competitor, who liked really big gears and didn't pedal especially smoothly!
Both my wife and I have frames with those lugs, so I am definitely not slamming them. I just think they could have been a little more perfect with just a little more metal in a key area. On high-end bikes, almost any fatigue cracking is cause for study, because we know the rate can be vanishingly small (unless we're really pushing the limits). Head tubes should NEVER crack on quality, handbuilt frames. Any such cracking makes me think the lug design is sub-optimal.
But for the majority of such bikes that do last forever, what does it matter if I think the lug was suboptimal in some way? Not at all.
Man, words... hard. Communicate... must THINK... Nah, too much work.
Mark Bulgier Seattle WA USA
> -----Original Message-----
> From: joebz@optonline.net [mailto:joebz@optonline.net]
> Sent: Friday, December 01, 2006 11:18 AM
> To: classicrendezvous@bikelist.org
> Cc: Mark Bulgier
> Subject: Re: [CR] Bikini lugs, cracking the head tube
>
> e-Richie has pointed that's an otsuya lug not an eisho on the
> Tesch! So this is a test case as I'm heavy and I rather like
> this bike. I have no idea how it was used before I bought it.
>
> Joe Bender-Zanoni
> Great Notch, NJ
>
> ----- Original Message -----
> From: joebz@optonline.net
> Date: Friday, December 1, 2006 11:13 am
> Subject: Re: [CR] Bikini lugs, cracking the head tube
> To: Mark Bulgier
> Cc: classicrendezvous@bikelist.org
>
> > Eisho, still holding up (under a substantial load) on my
> Dave Tesch.
> > Tesch was a big user of Bikini lugs in the US.
> >
> > http://www.classicrendezvous.com/
> >
> > Joe Bender-Zanoni
> > Great Notch
> >
> > ----- Original Message -----
> > From: Mark Bulgier
> > Date: Friday, December 1, 2006 10:57 am
> > Subject: [CR] Bikini lugs, cracking the head tube
> > To: classicrendezvous@bikelist.org
> >
> > >
> > > A beautiful artisanal custom bike I saw recently had a fatigue-
> > cracked> head tube, right at the downtube lug edge, and it was
> > not nearly the
> > > first one I've seen.
> > >
> > > The cracked frame had lugs filed down so small that they
> fell into
> > > the category of "bikini" lugs. (The name doesn't refer to "two-
> > > piece", as with the swimsuit, just the tinyness of it. A lug that
> > > doesn't cover up much of the joint.) That's not a bad thing in
> > > itself - I like bikini lugs.
> > >
> > > In my experience, lugs with a too-small "hand-full" of head
> > tube will
> > > sometimes (depressingly often in fact) cause a crack in the
> > head
> > > tube at
> > > the DT lug, for riders over a certain size/weight and/or
> miles/power
> > > combo. Cracked head tubes are relatively rare for frames with
> > a
> > > littlemore meat there in the DT lug - including cheap frames.
> > >
> > > An example: Of the two ultimate (to me) '80s-vintage
> > investment cast
> > > bikini lugs, Ohtsuya and Eisho, the Ohtsuya will crack
> head tubes at
> > > the DT for big/strong/hi-mileage riders, where the Eisho
> won't. The
> > > difference is subtle, but enough.
> > >
> > > Eisho is probably best known from Nagasawa:
> > > http://bulgier.net/
> > >
> > > I don't have a great photo of the Ohtsuya DT lug but I think
> > you
> > > can see
> > > the problem area here:
> > > http://bulgier.net/
> > > Look for the red arrow. The lug's grasp of the head tube
> > tapers
> > > down to
> > > nearly zero (under 1 mm) at that point, and that's where the head
> > > tube crack starts. Eisho has just a silly millimeter or so more
> > meat
> > > there,enough to put fatigue cracks out of the question
> for all but
> > > the most abusive riders. Overall though, the Eisho is
> just as small
> > > a lug.
> > >
> > > For years (late-80s - early 90s maybe?), Richard Sachs's
> ad in the
> > > bike magazines was a picture of someone's hands holding a file
> > poised
> > > over a
> > > lug. (Presumably the hands are e-Richie's - though he
> wasn't known
> > > by that name yet!) The lug in the ad is an Ohtsuya DT, which is
> > > pretty funny in itself, since there is NOTHING to file on those
> > > lugs, but especially funny because the file in the photo is shown
> > > poised to file RIGHT on that one edge on that lug that is already
> > > way too
> > small
> > > - at
> > > the red arrow in my photo. I believe this was an in-joke
> from Richie
> > > to the few people who knew how ridiculous it was to file right
> > > there, on that lug.
> > >
> > > Just so we're clear - this is NOT a slam on Richard
> Sachs, who has
> > > designed lots of lugs, all of which have plenty of meat at
> > that point
> > > I'm talking about. All the more reason I think the photo in
> > his
> > > old ad
> > > is an in-joke.
> > >
> > > The moral is, lugs can safely be carved down pretty darn
> > small, but
> > > there is a minimum, which varies from one area to another
> depending
> > > on the stresses on that area. And the headtube edge of
> the downtube
> > > lug is one area where some lugs are carved down too small - fairly
> > frequently> actually, in my experience, at least among high-end
> > or custom
> > > builders.(Cheap frames break too of course, but for different
> > > reasons and mostly in different places.)
> > >
> > > Mark Bulgier
> > > Seattle WA USA