Every bike curmudgeon on the internet will grumble “steel is real” if you trot out an old frame. Steel frames last forever, you’re told, and are easily repaired if anything breaks. Well, my old steel bike broke on its first mountain bike trail, so I took it to custom framebuilder to get brazed back together. The process is fascinating.
I’ll say that I had a real decision in front of me when my 1987 Schwinn Cimarron snapped its frame on a trail up in Vermont.
Let’s see those snapped seatstays. These hold the back of the bike up, and the pointy parts were indeed pointing rather menacingly at my more sensitive regions. You can see the rusty finger of steel still stuck to the frame at the lug, with the seatstays flopping to the side. (Seatstays are what connect the rearmost point of the bike to its topmost point—two tubes running from the rear dropouts where the back wheel goes to the joint of the top tube and seat tube, where your seatpost fits in.)
Anyway, my options. I could:
Give up on this particular frame and buy another Schwinn Cimarron to swap parts onto.
This was a viable option. Another Cimarron of the same size was kicking around in New Jersey, but driving down seemed like a pain, and I could only assume that whatever problems sprouted up on my Cimarron would be present on another one, too.
Give up on this bike altogether and get something modern and not a piece of garbage. This was the sensible option. Some companies still sell new steel mountain bikes with no suspension, such as the Surly Bridge Club. They are handsome and cost about a grand. I could buy one and move on with my life.
But is the point of life to do the easy thing? Why not take the difficult road, and learn something along the way? Moreover, what’s the point of having a steel bike if you’re not going to take advantage of it being fixable? After a few texts and phone calls, I was able to track down someone willing to repair the bike by brazing it back together. It’d be fun to see and document the process, anyway.
This is the option I took, even though it meant blurring the line between work and goofing off with an old bike.
I also wanted to do it because it’d be a chance to learn more about the process that, well, was the whole reason why I bought the bike in the first place.
That is brazing. Now, there are basically three ways that bike frames are put together.
1. Lugs: This used to be the standard way that bikes are put together. Tubes are joined at the joint by fitting into little elaborate sleeves. This is pretty, and elegant. Some people live and die by lugged bikes, which can get a little fiddly if you get too into it.
2. Welds: This is the current standard way that bikes are put together. It’s fast, it’s strong, but it’s also a little abrupt. The tubes just butt up to each other, and you can see the welds joining the tubes.
3. Brazing: This is the odd one out. The front of my bike is joined like this in a process called fillet brazing, where the tubes are joined with a different metal melted onto them. You can see how my Schwinn Cimarron’s headtube has no ridges of lugs, like you can see on the fork, or beads of welds, like you’d see on a new bike:
That fillet brazing is pretty much why I wanted to scoop up this bike. It looks interesting, and it’s how a lot of the early custom mountain bikes of the 1980s were built in little shops in Northern California. I’m from Northern California! I grew up not far from those shops. My crusty old Schwinn feels like it’s close to that history.
Also, fillet brazing is genuinely lovely, and almost a shame when it’s covered in paint. Here are two fillet brazed stems that Johnny had in the shop. The one on the left is polished up, the one on the right not yet. You can see the fillet brazing clearly: it’s everything that’s bronze.
It’s skilled work, and it leaves these super smooth joints, like the tubes of the bike are all melded together in one, clean form.
At least that’s how I always thought of it. Brazing, as Johnny Coast explained to me in his shop on the other side of Brooklyn, is much more common in bike construction than I thought. Lugged bikes are technically brazed together, as are many of the little joints you see on all kinds of bikes. As it turns out, the definition of brazing is rather broad.
Brazing is like welding, in that you’re joining two pieces of metal together. Welding means melting both those pieces of metal into each other. You’re heating up, in the base of a steel bike, two pieces of steel tube so hot that they melt, and when they cool they cool down into one solid piece. Brazing is to join them together without melting them but to melt a second kind of metal around them. In the case of my bike, that means jointing two pieces of steel with bronze. You don’t have to heat the steel up to the point where it melts, just to the point where the bronze melts around it. When it cools, everything is glued together. Joe at Cobra Frames has a good explanation of it, and relates it to soldering:
The trick about brazing a bike, as Johnny Coast put it, is that you’re not exactly gluing two pieces of steel together with bronze. The process works on a molecular level to bond everything up. Here’s Johnny helpfully illustrating how the metals join, as represented by wiggling fingers:
This is why the brazed joints on a bike still hold up to decades of use even though there’s actually very little surface area joining things up.
The other thing about it is that it is very fun to watch.
It took messaging a few framebuilders until I got a positive reply from Coast. I dropped the bike off and returned a week later to see some of the actual brazing in action, the actual forming of the new seatstays to replace what snapped off my frame. It would be nice to see the.little time-consuming details come together.
To start the brazing process, Johnny first brushed the metal with something called flux. This is a chemical concoction that “prevent[s] contamination of the parent and filler materials” as noted by Framebuilder Supply. Basically the flux melts and keeps out everything but the steel and the bronze. It’s what Johnny watches to help gauge when the steel is at just the right temperature to start brazing. The blue foamy flux starts to bubble, then turns glassy as it becomes ready. From there you just bring the bronze to the glowing, glassy mess of steel and flux, and the bronze melts into place. It actually works through capillary action; the bronze travels towards the heat, guiding itself to the joint. “I’m just asking it,” Johnny says.
The way he puts it, the whole brazing process is making the environment right for the bronze to melt and set right. It’s about creating the right conditions, and the metal does the rest.
I think of welding as kind of meditative—that you need your steady hand, your patience and precision to set a good bead. Brazing feels almost comically positive. You’re just making a nice, positive environment for your bronze to do its work. Every time Johnny raises his hand away from the glowing tube, a bit of the bonze rod has simply disappeared, like it left for college or something.
It’d be a similar process for joining the seatstays themselves to the frame. Brush them with flux, light ‘em up with a torch until the steel glows and the flux turns glassy, then let some bronze melt them together.
I’ll also say that at each point of the process, Johnny was happy to point out each place where Schwinn cheaped out during the construction of my bike. Everything in bike production, as Johnny explained, is just about time. Making a bike as quickly and as easily as possible is how you make money as a major bike manufacturer. My Cimarron, as he noted, was full of little cut corners.
On my bike, the seatstay’s original ends weren’t brazed on but just smushed into place. Johnny was going to braze on new end plates for them, which is prettier, smoother, and stronger.
On my bike, the seatstays were brazed right onto the frame. Johnny filed a little groove into each side of the lugs on my bike’s frame to get them to sit better. Small details, but meaningful ones that differentiate a high-end bike from a low-end one, a production bike from a custom one. Coast point out little punched holes and other signs of cheaper construction I could have never recognized on my own.
We also got to see that a failure like the one I had was definitely coming at some point. At one point Johnny pulled out my old seatstays to talk about the metal bridge that spans them. As he wiggled them in his hands, the bridge snapped clean off, showing that it had gone rusty inside. I would be lying if I didn’t fear that, well, probably this whole Cimarron is a rusty pile of garbage that will fail at every joint possible. But by the time that happens I’ll be a bit wiser, unless it breaks on a trail again and sends me flying into a tree.
We walked into the backyard of his shop, past the Bridgeport and other machinery, past the custom frames hanging from the rafters, past the ‘70 Ford Ranchero he just redid the front suspension of, and past the wood-fired heater in this old Bushwick building, not far from the elevated subway. In the back were all kinds of bikes. He helped start Bike Kill and a tall bike stuck out from under a cover, looking like what it was: a handful of bikes welded into.a tower, each wheel turning the one below it like a set of gears. He pulled up frame after frame, pointing out where each one had been brazed, from the grimiest old Raleigh to the swankiest fillet-brazed Landshark, a cult-classic bike also in for repair.
I got this Cimarron because I thought it would be like touching a little bit of the low-volume, custom magic that bikes like that Landshark had. I guess I was cutting corners to get it, and I’m not surprised to find that Schwinn cut corners of its own putting it together.
But I’m glad I’m getting a chance to make something interesting out of it. I’m glad, also, that I have a better idea of what “steel is real” actually means.