Ago15

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lasauge 

Wow, those brake mounts in particular are interesting. How do the expanding seatposts work? Seems like a typical quill setup would get in the way of the rear brake cable.

sovende

Was wondering the exact same thing

smd4

I asked that question earlier. Another poster suggested there may be slots drilled into the seatpost.

Something I totally missed earlier: there are no brake bolts on the backs of the forks or brake bridges!! How does that work, I wonder?

Ago15

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dedhed

My guess on the brake mounts is a threaded boss with a stud screwed in and the brake assembled in place. Sure seems like it's be a PITA to deal with.

smd4

That makes sense. Makes for a clean look, at the expense of ease of maintenance.

bulgie 

There are various ways that have been used in the past. In the early '70s, a couple of Italian builders I'm aware of and at least a couple British bikes I saw had Campy brake centerbolts brazed on. This bothered me slightly as it made brake-centering adjustment impossible, other than by bending the spring, which is do-able but seemed inelegant to me. Also the heat of brazing almost certainly weakens the centerbolt. Still strong enough for anything short of crashing, but I wanted mine to not have any weakened HAZ (heat-affected zone).

So on my one and only frame I made with "brazed on" brakes in 1977, I solved those two quibbles. The braze-on is a sort of hockey-puck-shaped piece of steel with an M6 internal thread. The actual centerbolt was a piece of an M6 high-strength "aircraft" bolt, with threads on both ends. It threaded into the hockey puck and was secured with a setscrew, so no heat. Then for the piece with the slot for the spring, I made that from aluminum, with a recess in back that fit over the hockey puck, so the spring holder can rotate to center the brake. Then the alu part was slotted on both sides, with small screws that went through the slots into the puck, to lock down the centering adjustment.


That's the only pic I have of it, a scan from a print from a bad snapshot camera. You can just make out the top of one of the slots where the alu piece is secured to the puck.
Although I was too poor then to afford a decent camera, still I rode on Clement Del Mondo Seta tubulars — priorities! (Actually the tubs were hand-me-downs from club members who flatted and didn't want to repair them. I got good at sewing.)

All that work resulted in a brake that worked exactly the same as any other Campy brake, whoopee! Just with the dubious bragging rights of not having a nut on the other side of the bridge and crown.

In my defense, I was 19 years old when I made that frame. It had other goofy stuff on it that I later regretted, like a "seat mast" — the seat tube continued past the seat lug all the way to the saddle clamping mechanism. It was a dumb idea then, and still dumb when that idea was resurrected decades later.

On the subject of who made the "best" fillets (however that is defined):

Even back then in the '70s I was a fillet specialist, making tandems all day at Santana. In my subsequent jobs at other frame shops I was "the tandem guy", plus with all the lugless MTBs and funnybikes and such, I laid miles of fillet over a couple decades, got pretty good. One thing that all those years of looking at fillets does is it trains your eye to see the subtlest signs of improper or over-done filing. I can say with complete confidence, there are probably a dozen guys in the US who did finer work than this Mercet guy. I see signs of undercutting, where the tube wall has been thinned from over-filing, and some edges that weren't completely smoothed. Nice work for sure (if you like gagantuan fillets, which I do not), but nowhere near the best I have seen.

The overly large fillets on these Mercet frames are grotesque to me, but my aesthetics are largely based on function, so maybe they aren't so bad from a purely sculptural point of view, that is, as wall art. If you're going to actually ride it though, there's no getting around the fact that these ridiculously large fillets are just extra weight that does nothing for you. In fact they weaken the steel, due to the extra time taken to lay them down, the extra heat that entailed, and the slower cooling rate due to all that added thermal mass. Bigger, weaker HAZ. The frames are obviously strong enough, for the amount they got ridden (looks like not much...), since they haven't buckled or cracked (yet), but they are definitely weaker than those same tubes would have been if they'd been brazed quickly with minimal-sized fillets. Add to that the fact that there's also some undercutting evident in these pictures, and thin-wall tubes such as EL being used, where even a little undercutting is a more significant fraction of the total wall thickness.

Early Santana tandems had large fillets (not Mercet-large, but still too big IMHO), but as soon as I moved on to my next posting, making Rodriguez tandems, I downsized the fillet size considerably. Still bigger than they need to be, confirmed with destructive testing, maybe twice as large as the minimum needed for strength. Bicycling magazine tested a Rodriguez I built in about 1980 and said "Is there a tandem more advanced than the Rodriguez? We haven't seen one." The testers were John Schubert and Gary Fisher (yes, that Gary Fisher!) Soon the Rod tandems had a 3-year waiting list. The frame Phil Wood used at the trade shows to show off their disk brakes was a Rod that I built, with no canti studs or any other place to mount a brake (against my advice!) I mention this just to point out that my frames were being seen and appreciated by a fairly wide audience.

Then a few years later when I was making tandems and other lugless frames at Davidson, I grew tired of finishing the fillets, plus I'd gotten so good at laying them down that they didn't need it. We decided to charge extra for smoothed fillets, and since customers couldn't see the difference in a painted frame, none of them opted to pay extra for smoothing, so I didn't have to do it anymore! I actively pursued techniques to braze faster, with the goal of minimizing the weakening of the HAZ and the size of it. Though it may sound self-serving to say it, the fact is the faster I brazed them, the better they came out. I was also making the fillets smaller during this time, with continuing destructive testing to show that the minimum fillet size for strength was still smaller than I was making them. Smaller fillets laid down faster also made for less heat-distortion. (How to spot a charlatan framebuilder: if he says "I don't get any heat distortion, they just come out perfectly straight." Uh huh and you knocked out Chuck Norris with one punch too I bet.)

Smaller fillets made the frames lighter too of course, though that wasn't the main goal. One small Prestige .6/.3 frame came out just under 2 lb, lighter than any lugged or TIG welded frame I ever made in steel. I only mention this because I've heard some people say fillet brazing is heavy. It can be <coughMercet<coughRitcheycough> but not necessarily!

Mark B

smd4

An excellent, very informative post, Mark!

We are frequently told that there are details in these frames that only are apparent to someone with a “trained eye,” so it’s interesting to hear from someone with that eye.

billytwosheds 

In slightly modified words of The Dude, "You're not wrong, Walter. You're just an [jerk]."

Bulgie's post was by far the most useful thing that's come out of this thread and the last one.

It seems the OP learned little or nothing from the last.

Atlas Shrugged

As I mentioned in the previous thread. These bikes are nothing but the bicycle version of Performance Art. A unique interpretation of what a custom bicycle should be but fails on all counts. Might be nice to hang in the wall of a bicycle cafe or something however even then those in the know will see it for what it is. Much like those car show vehicles from the fifties, something for uninformed teenagers to lust after thinking the girls would go wild however in reality they couldn’t get out of the parking lot.

SirMike1983 

I owned this fillet brazed 1947 Schwinn 3 speed for several years. I eventually sold it back to the previous owner when I moved back north.

SurferRosa

Third time's a charm?

.
I don't know enough about them to know if that's the case, but if so, I think they could really benefit with more thought in their photography. The backgrounds used for the detail shots are pretty poor. This is a little better:

smd4

I asked about weight in a previous thread and was told the bikes weigh about 19 pounds.

Alexbaker67

Mark - that was one of the best posts I’ve read in quite a while. Just last night I was tempted to comment on the artistry of your fillet brazing. I have one of the early Discovery tandems that you built while at Davidson, and I constantly marvel at the exquisite quality of the brazing you did on what was supposed to be a production line bike. I have fond memories of chatting with you when I worked at Elliott Bay as a lowly stock boy in the mid 80s. It’s always a treat to read your insights on this forum, and it takes me back to a great and very formative time in my life.

- Alex “Big Al” Baker

bulgie 

You're very kind, thanks.

I was mostly hands-off from the Discovery line — they were made by the rest of the crew, while I made the custom frames. I can easily believe that I would have lent a hand if we were making one for "one of us" though (co-worker). Or maybe I actually did the fillets myself, on early-days Discovery tandems, and I just don't remember? Could be, I wouldn't be surprised if you remember it better than I do. ("CRS" sufferer) On the other hand, there never was a time when there wasn't a waiting list for customs, so they tended to keep me working on the customs. My guess is Rick Gnehm was the guy that actually fillet brazed most Discovery tandems. He later had his own one-man shop; called his bikes "Banana Boy". Or maybe Frank Kaplan.

My main contribution to the Discovery (that I do remember) was in training the workers, some quality-control, designing/testing/tweaking fixtures and processes they used, etc. A lot of the fixtures and processes were worked out by Bill before I got there, not claiming I did it all. Plus everyone on the crew came up with improvements too, it was very collaborative, a fun place to work.

Sorry going way off topic, I'd better bleave it at that.

-mb

masi61

Ago15 - I like the chrome plated frame the best. Super gorgeous. Could you explain the mechanism for securing the seatpost to the frame? I’m assuming that the secret lies with the Campy seatpost. I’m not familiar with Mercet. Is this a Swiss brand? I have seen some Moser frames with fillet brazing like this but that plating takes it to beyond show quality.

One more mystery I am curious about: the internally routed cabling. Are there sockets or ferrules set into the frame that we are not seeing that act as stops for the housing?

T-Mar

These are quite nice pieces of industrial art. Fillet brazing was a popular technique when lugs didn't work (i.e odd angle frames, oversize diameter tubes, non-round tubes, etc.). That is one of the reasons why it persisted for so long on tandems. It freed the framebuilder/designer to explore new avenues prior to the development of internal brazing and the advent of TIG welding.

Its appeal these days is primarily aesthetic, a point not lost on a membership who prefers fancy crowns and sulpted lugs over Unicrown forks and and TIG weld beads. As already pointed out, these are massive fillets and are reminiscent of aero frames of the early 1980s. Consequently, they are much heavier than necessary and compromise the joint. There are certainly cheaper, lighter and stronger ways to join two tubes.

Even as art, I have some quibbles with these frames. The huge, aero joints don't work aesthetically when the bicycle is equipped with non-aero components. To my eyes, the sharp, pointed transitions from the stay ends to the rear dropouts, stand out in a jarring contrast of styles with the smooth, flowing transitions of the other joints. All the little touches, such as the exiting of the rear brake cable, rear derailleur housing and blind brake mountings are a little too complex and non-practical for my tastes, in what I consider should be an elegant but simple machine.

Of course, as art, it's subjective, personal opinion and as industrial art there's a melding of aesthetic and function for which each individual is going to have a particular blend that they consider ideal. Obviously, this mix is perfect for the OP and it's wonderful that he shows such enthusiasm for the brand. I can certainly appreciate his viewpoint and consider them quite nice, even though I find them somewhat disjointed and and the blend does not result in my ideal cup of tea.

Wileyone 

Non Aero.

Oldguyonoldbike

I have a fillet brazed Casati that I have mixed feelings about. I’m curious to hear the experts’ take on the welds here.




Seat post is held by an internal clamp. There’s a hex bolt accessible from the other side of the frame. I never have liked the inelegant transition from the oversized seat tube.

smd4

If only looked at as art, I think these frames succeed. I think I would have been drooling had I seen one at the 1987 Interbike show.

As efficient racing bikes, however, I now see their limitations and drawbacks.

BMC_Kid 

Gorgeous. Truly works of art.