Ann: Let me start with some basic history here, was it Gary Helfrich that introduced you to working with titanium, or did you have prior experience through any of your machining work?
Mike: No, it was purely Gary. I don't know exactly how he got interested in it, but he heard that it was impossible, so then he had to do it. You had to have a military or aerospace budget to be able to work with the stuff, supposedly. You had to have a whole room full of argon, he was told. And he figured out a more low-tech way to do it.
Ann: So he experimented with more localized argon shielding.
Mike: Right, well you purge the inside of the frame, of course. That part's actually easy. Then you use a larger cup on the tig torch, and long post flow, and you go really slow. It took him a while to figure it out but, then when he did, when he finally got it... the way he worked was there were a few stillborns, some of the experiments didn't turn out that well. If you don't get the purge just right then it becomes extremely brittle, and you wouldn't get more than one ride out of a bike if it was purged badly. But then he got it figured out, and that's when he said to me, I was working at Fat City part-time right around then, he said “here take it out,” and he loaned me the bike overnight. Gary was definitely my introduction to titanium. I didn't really know anything about it before that.
Ann: I see.
Mike: He had some sample pieces. He loaned me a couple pieces just to put in the lathe to see how it cut, and he loaned me this bike that he had made. And everyone was just completely shocked at how light it was.
Ann: Obviously, at a certain point, titanium captured your imagination. What about it really grabbed you?
Mike: Well, it's a combination of things. It's kind of a remarkable combination. The weight, the corrosion resistance, the fatigue life. Those are the three main ones. The strength. It's not really stronger than steel, but if it's as strong as steel and has a better fatigue life, and doesn't ever rust, it's kind of a remarkable bunch of features that make it appealing.
Ann: That all makes sense.
Mike: In fact, this was back before we had suspension, and I've had people say to me, the first Merlin they bought, which was probably all inch-and-a-quarter tubes, was like riding a rubber bicycle, by today's standards... and that allowed them to keep riding! One guy said he had to stop riding mountain bikes, because his wrists were so bad, and he got a Merlin, and it was so soft, he could ride again. That might be an exaggeration, but the early ones were faster, in spite of the fact that they were so flexy, because nobody was riding suspension yet.
Ann: That's amazing!
Mike: Nowadays, that flex in the frame, it's meaningless.
Ann: That leads me right into my next question. Years later, when you were working on the titanium Slingshot bike, did you ever consider a full-titanium design, omitting the 3M 'Flexboard,' and just using a thin titanium plate there instead? Given the flexibility and fatigue resistance?
Mike: At that time I think I was aware that John Castellano was using that technique, with some success, but I don't think I would have risked it. Because the whole frame is held together by just that composite leaf-spring, and that's proven to hold up over time. It's really strong, and the SlingShot people had proven that it really lasted. I don't think I would have had the guts to use titanium for that job. And I have seen plenty of the Castellano frames break.
Ann: Really?
Mike: Probably five or ten years ago I had done more frame repair than anyone I knew, because nobody else wanted to do it. Litespeed's not going to repair a Merlin, and Merlin's not going to repair a DEAN, so they'd all come to me. It was kind of fun, I got to see everyone else's broken frames.
Ann: I've always wondered if there was some traceable line of inspiration from the bike that you worked on with Roo Trimble, to the Ibis Szasbo, and then on from there through the various Ibis bikes.
Mike: I think Castellano would argue that he thought of it first. Of course Roo Trimble thought of his design on his own, independently. One year we went to the trade show, I think it was the one with the big race at Mammoth. Castellano had a t-shirt that he had printed up, it had a patent drawing of, I want to say an Owen? An 1890s design, maybe 1896. Anyway, this shirt, it was a joke because Gary Klein was upset about patent infringement at that time. He was mad at his lawyers because he was trying to patent this--what we called the Unified Rear Triangle (URT). So Castellano had this shirt printed up of this 1890s design that showed the same thing, this URT. So it was really kind of un-patentable, or your patent was always going to be narrowed down so much that it wouldn't be worth much. That shirt was Castellano's answer to Klein's lawyers.
[I tried finding a patent drawing attributed to an Owen, with no luck. An H. A. Becker did, however, have an 1890 patent on what appears to be a high-pivot, URT bicycle]
Ann: That is very funny.
Mike: What Castellano ended up patenting was the location of his pivot. He disagreed with Klein's really high location. Roo Trimble and I wrote a patent on the URT, that he ended up abandoning. Most patents aren't worth the paper they're printed on anyway. But you do it for other reasons. You do it to get the attention of the larger companies, you don't do it because you expect to make a million because no one else can copy it. You can always get around a patent, just about.
Ann: Interesting.
Mike: There were so many patents in the bike industry at the turn of the century, they had to open a second patent office. There was such great innovation going on back then. URT would be a natural development because they wouldn't have a derailleur to take up chain slack. So if you're going to have the rear end swinging, the bottom bracket and the dropouts needed to go together.
Ann: Was your thinking about the specifics of URT design informed by your time working on the Slingshot?
Mike: No. Well actually, Roo did all that. He put the pivot where he wanted it, which was on a line between the head tube and the rear dropouts. I think that's best, and I think he got that right. It makes the travel somewhat the same whether your sitting or standing, but the story that Roo would tell you would be sort of similar to the Slingshot story. The Slingshot story comes from a broken frame. Roo's story is that he had a Giant Iguana, that would be the model name, and I think it was actually a ladies-frame mountain bike, and it broke, and it's a very similar story to the Slingshot people. He thought “woah, the frame broke, but I can still ride it. All it needs is a pivot here, and a spring and tension here,” and so he called it the Iguana Flex.
Ann: While we're still on the topic of the Slingshot, is it your understanding that Slingshot modified their geometry [lowered the top tube pivot point and standardized the seat tube length on all models] in response to the work that you did on your titanium frame?
Mike: Yes. They stopped making the seat tube longer for taller riders, because you don't want that pivot point to go up. You just make the seat post longer. That was the main change.
Ann: I've always wanted to try riding one of those.
Mike: I have a magazine clipping from Bicycling where they said it was the fastest, lightest mountain bike they ever rode. Again, that was before modern suspension. It was actually pretty awful in really tight technical situations, like if you're trying to ride along a railroad track, a trials move, the frame was so flexible that it's almost impossible to ride. If you're totally relaxed, it's fine, but if you tensed up, you would get this unwanted wiggle.
Ann: For the top tube on the Slingshot bike, and also on some road bikes, if I remember right, you used a composite honeycomb-infill. Tell me about that.
Mike: Yes, there were two road bikes. There was a friend of mine, Mike Ballou, his last name is on the bicycle. He was working at a place that was making airplanes invisible to radar, and they used a lot of this fiberglass honeycomb. They would dip it in this black coating, I don't know what they were doing with this fiberglass, it would have been structural I would think. Anyway he would get a lot of this fiberglass out of the dumpster where he worked.
Ann: [laughs]
Mike: We were trying to get the titanium to be stiffer. We didn't really have many tubing diameters at all. We were good friends, we did a lot of things together, so he knew that I had a lot of tubes that were an inch-and-a-quarter, and the wall-thickness was crazy thin, like .020. It was CP [commercially pure] welded tubing, way too thin to make a bike frame out of. And he thought that would be perfect. So we made a hole-saw by putting diamond coating on the end of a piece of titanium tubing, and then we just plunged it into this fiberglass honeycomb block. He knew all about the kind of glue to use, he was the Glue Guy, we called him. That all came from him.
Ann: Fascinating! You said there two of those that were made?
Mike: We made one for him, and it had the fiberglass in the fork and in the stays, and then he found another guy, a customer, that he came to me with, and that's the one that's in Switzerland now.
Ann: Do you have any weight figures on those?
Mike: Well, it was lighter, but we did some testing on them. You're always trying to get a frame to be stiff in vertical compliance, for example if you hit the brake hard, you don't want it to chatter, but if you're bottom bracket is swinging from side-to-side while you're pedaling, that doesn't matter so much. That's not as bad as if it chatters when you hit the front brake. You always want it stiffer in one plane. If you can get a differential, that's what you're looking for. The honeycomb did that. We had an Instron strength-testing machine, where you've got a jig and you put whatever you want in there and it presses it until it breaks, so we testing the tubes in there. And we have some documentation that it did make it stiffer in one plain, relative to the other. So we thought, that's worth it, let's just go with that. It was worth the trouble because of the differential in the stiffness.
Ann: Let's talk about your Moulton project. That must have been extremely time consuming.
Mike: Yeah, that was my favorite thing. That was what I wanted to do and it was a great job, I was so glad to get that commission. That first Moulton that I made, I think I got $7,000 for that. It was a frame, fork, seat post, stem... I think there was even a fairing mount, that was made of titanium. That guy, I don't know what happened, but it ended up appearing in this collection, this Austrian guy. And I have this hardback book, which has that guys 100 favorite bikes in it. But something happened and he had to sell his collection. It all went up at Southebys, and I got it track it, and it sold for more than any other bike in his collection. I mean it sold for $35,000.
Ann: That's Michael Embacher's book, Cyclepedia?
Mike: That's right. Yeah, somebody really wanted that bike. I actually got a call after that, from somewhere in the Middle East, maybe Saudi Arabia, and it was the new owner, he wanted to ask me a couple questions about it. The other one I made didn't have a suspension. That's the one where I used water-bottle cage tubing for all the little tubes, that's quarter-inch, .016 wall tubing, which is incredible, you would swear it would float, it's so light. And so that one weighs a lot less than the one in that Embacher book.
Ann: And that one's full-rigid?
Mike: Yeah, that one's pretty nasty to ride. You want to find somewhere really smooth to ride it. It's just so stiff. It's the weirdest feeling, when you've got that inch-and-a-quarter head tube, and the fork being really short, it's stiffer just because it's so short. When you engage the front brake on that bike it feels like it's made out of stone. I mean I never rode a bike even remotely that stiff, when you hit the front brake hard.
Ann: I think I saw also that you had made one or two titanium SoftRide bicycles?
Mike: Yes. One of them, it's here now. The customer who originally ordered it, he said “oh I'm a runner, not a cyclist, I never sit down.” And he just took the SoftRide beam right off. And there was no way that bike was going to be strong enough, the guy was like 200 pounds, and he rode centuries, standing up, in the big ring all the time. So it broke the frame! I repaired it, and he broke it again, and I finally convinced him to just let me have it. I said I'll make him a whole new frame, just for him, that's made to stand up, and you know it'll weigh a half a pound more but at least it won't break. Anyway that's why I have the SoftRide frame here again, I had to repair the rear dropout where he broke it.
Ann: Incredible.
Mike: Yeah. We're actually selling our titanium museum right now. I have quite the collection. I have two of the URT bikes, the Trimble suspension bikes. And I have what we called the titanium Mountain Trials, which was back... 1984, 1985. It has a 24” wheel in the back and 26” in the front, we wanted to get it as short as you possibly can, for really tight trails. I wonder what else I have... For a while there, people would come to me and I would just make whatever they wanted. I made a rear end for a ProFlex, out of titanium. All kinds of goofy things. A jewelry box. A fireplace grate. The list goes on and on. 700 titanium wedding rings. That was how we paid the bills.
Ann: How funny. [At this point we got off-topic for a bit talking about a Teledyne he had. This lead him to say that he felt that the problems with the Teledyne bike could be chalked up to Eisentraut's traditionalism, and the conversation came around to the dominance of traditional road riders in the industry, and how that influenced design trends]
Mike: That's the way it was early on. Everyone, Tom Ritchey, Chris Chance, total road riders. Almost all these people. But Gary and I, we weren't at all. I remember Gary and I, we were going to build a bike to try to promote titanium as a building material. We were talking to Jim Redcay from Bicycling Magazine. And so we were going to make a bike to his specifications, so he would ride it and test it and give it some publicity. And I said “do you mind if we make the top tube sloping?” and he said “well, I don't know, it makes it kind of hard, with a long reach to the handlebars...” and we said “no, no, sloping the OTHER way!” He thought I meant the top tube sloping down, toward the head tube! That's how much of a road rider he was. But look at bikes now. Look at the Tour de France now. Are there any that slant forward? Or even with a level top tube? No, they're all compact now, it just makes more sense. Us being mountain bikers, we just said no. It should go the other way.
Ann: If that's the same bike, I think I've got scans of that from the Bike Tech journal.
Mike: We made the cover of that one time.
Ann: That's a good looking bike, and it's way ahead of its time with that very modern looking compact frame style. I was surprised to see that in, what 1987?
Mike: Yeah I have that fork, right here. It's a pretty good fork, even by modern standards. It's the weight of a carbon fork. Well the problem was the 1-inch steer tube. That diameter just isn't stiff enough with titanium. That's why Gary Fisher came up with the 1 1/4-inch headset size. He wanted to make a titanium fork, so he got his engineers to give him the calculations, and they said if you want to match the stiffness of a 1-inch steel steerer, you have to go all the way to 1 1/4-inch with titanium. So he said ok I'll make my own headset size. Which was just crazy, but, he did it.
Ann: Oh interesting!
Mike: And then I got a call, six months later or so from Tioga, and they asked me if I had any 1 1/8-inch titanium. And I said “No, there's no such thing, what do you want that for?” And they said what they always say, which is “well, we can't tell you.” And I said “if you don't tell me, I'll tell everyone that you're up to something with 1 1/8-inch and your secret will be gone.” So they told me they were working on a 1 1/8-inch headset size, because nobody likes Gary Fisher.
Ann: [Laughs]
Mike: I did that with the Aheadset people too. Dia-Compe, this guy John Rader, when the first threadless headsets came out, they wanted a titanium stem. They said, “well we're working on this new headset design, and we need you to make this custom titanium design for us.” And they showed me the drawing and I said “well, but how does that work? How do you get pre-load, how do you clamp on?” And they said “oh, we can't tell you.” And I said “if you don't tell me I'm going to figure it out and call everybody I know.” So they told me.
[laughter]
Mike: I've also done a couple of titanium wheelchair frames, at Merlin. There was a lot of interest at Merlin. And we were right next door to Bob Hall, the first person to enter the Boston Marathon in a wheelchair. And so he loved us, because we were working with titanium, and with steel, and so he couldn't get enough of our shop. He was a competitor at the time and making his own, and making his own racing wheelchair frames. So we did that for a while.
Ann: Right, are you still working on the hand-cycles currently?
Mike: No, it's been a few years now since I stopped doing that. I did it for 17 years, and made 190 of them. The whole time I was saying “how many of these do I have to make?” That's why I named my company One-Off, I just wanted to make the first one, get that working well and then go on to something else. But in the wheelchair industry, there's no real money. The big companies will just buy up anyone small and stifle them. So I knew that if this design I had was going to go anywhere I had to make a bunch of them.
Ann: How do you feel about titanium as a framebuilding material today? Is it something you're still interested in? Do you feel like it's been eclipsed?
Mike: Well yeah it's definitely been eclipsed. I mean, I have a titanium frame tube, and a carbon fiber tube, a piece of top tube, they're pretty much equivalent. And I hand them both to people, and you can feel the carbon fiber tube is lighter, when you try to bend it over your knee it's stiffer. I saw a thing this morning that I just chanced onto on YouTube, it's about a titanium frame that uses additive machining. 3D printing.
Ann: Oh right, sinter welding and things like that.
Mike: They 3d printed the head tube area and the bottom bracket area, and it makes like a lug. And then they welded in the tubes. But I really don't trust the quality of the 3d printed titanium yet. And it looked pretty bad, it looked really rough. And it's probably heavier too, although they didn't mention that in the article, but I bet it's heavier. But maybe, eventually, that's the way things will go. And it won't be so expensive, and the joints will be easier to do, and you'll be able to optimize some of the areas that need it for the stiffness.
Ann: I've been in contact with a few, basically hobbyist frame builders who are having whole joint areas 3d printed for them, to their specification, and then basically weaving their own carbon fiber and bonding it all together.
Mike: Oh wow. Well I guess I don't know the metallurgical properties of this 3d printed titanium. I'm going to start out very skeptical about that.
Ann: I've heard of these parts being pretty brittle in certain applications. So yeah, it probably warrants skepticism at this point.
Mike: And the price? And it's a very slow process... And the welds were all--at least on this bike I saw on YouTube [it's a bike by Sturdy Cycles]--the welds were all straight around the tube.
Ann: Oh!
Mike: So, that's a stress concentration. You kind of want the welds, the way that old-fashioned lugs have the points, to spread out the stress. And none of the 3d printed titanium lugs had that feature. It was all just cut-off straight. So it really wants to break at the welds right there.
Ann: That brings me back to an earlier topic, can you clarify the construction of the chain stay lugs on your SlingShot and other bikes?
Mike: Yeah I always did that. I built all my frames like that because I was tired of repairing Merlins, which always broke at the chain stay bridge. So I said, ok, I'll just leave out the chain stay bride, so it'll break somewhere else. [chuckles]. So instead I used, um... 7/8, 16th-wall? for these little three-to-four inch long lugs. And I cut them off, with the lug shape like we were talking about, with the point. And what you do is you stick in that ¾ tubing, that's the chain stay, that fits perfectly inside that tube, and then you squish it in a vise so it's ovalized, and then weld it.
Ann: And you just weld right along the lug edge? I see.
Mike: Yes, just a minimal weld there. Titanium frames really want to break right there. We made them too light at first. At first we thought seat tubes can't break. It could be a light as you could possibly make it and there's no stress in the seat tube, so it won't break. Well that was wrong.
Ann: I think that's all the questions I have for now! Thank you so much for talking with me about this stuff!
Mike: Sure thing, it's fun to talk about.