How I built my bike frame
This is a resurrection of a webpage I put up about 10 years ago, in 1998. The page disappeared several years ago when I changed servers. I recovered the photos from the wayback machine, added a few updated comments, but mostly the info is unchanged. The bike itself saw lots of miles, but was finally retired in 2012. I cut it up and used some of its tubing for other projects.
This is only a photo essay of my framebuilding experience. It is not intended to be a complete instruction in framebuilding! I am not suggesting that you build your own frame, or follow my example. Those looking for formal education on framebuilding should attend a class like the ones at UBI.
This is the story of the construction of my road bike frame. At this point, I had built several experimental folding bicycles, and was quite familiar with filing, cutting and brazing cromoly tubes together. The Patereck Manual was initial guide to bicycle frame building. On the experimental bikes, I had to figure out many of my own solutions to the construction. which kept the projects really interesting.
I did not use any jigs. I would generally set up the tubes and braze them, one joint at a time, just like Mr. Patereck instructed. I had to cold-set a few of the joints I brazed. Alignment was set by using straight edges and squares, and by visually lining up tubes to make sure they were absolutely parallel. Also, I would set the work against the life sized drawing of the frame to compare for accuracy, mostly with the head, downtube, and seattube angles and lengths. I probably came well within a millimeter in all areas.
The tubing was Tru Temper 9-6-9 basic stress relieved cromoly, which I purchased from Henry James. I preferred that to the hardened tubes, because it’s easier to file, drill, cut, and cold set. It’s a bit heavier (the weight of the frame and fork when finished came out to 6 lbs), but using the harder tubes would only have saved a pound or so. Brazing was with an oxy-acetyline setup, using tanks I got from my local welding supply shop. Brass fillets were used to connect the main tubes. Silver was used on the fork and braze ons. Some small parts I got from J. Gaerlan. Another good source for framebuilding supplies is Nova. I was a regular reader (and occasional contributor) to the Framebuilders List. I knew what I wanted: long wheelbase, lowish bottom bracket, steeply sloping 1″ top tube, lots of room for fenders with my caliper brakes, slack seat angle, and 135mm rear triangle.
When I made the drawing of the bike, I designed a fork that would accept a 700c wheel with long reach caliper brakes at full extension.. I measured everything carefully in the drawing, since any error in fork length will affect frame angles and bottom bracket height. I made the fork first, so I knew exactly how long it would end up, and I could use that info to make the drawing more accurate.
I decided to use a Henry James 3 degree bend fork crown. The 3 degree bend in the crown would put the blades 20mm forward. The blades would need to be bent another 20mm forward to get to the 40mm offset I wanted. ( just picked the 40mm number for a offset, because that is a common length). This would result in a unique, short fork rake. I used blades with 1.02mm wall thickness, thicker than they needed to be. Most steel forks for single bikes have 0.9mm walls.
First, after a thorough sanding and cleaning of the parts to be brazed, I silver brazed the crown to the steerer. I used 55% silver and a large #3 torch tip I took my time heating it up with a soft, neutral flame. I fed the silver into the crown from above, and made sure it went all the way to the end, where I saw a thin line of silver when I was almost finished brazing. Afterwards, I drilled a hole for the brake caliper in the steerer, through the casting.
Here is how I bent the blades. I got a wheel from the junkyard and brazed a small piece of tubing to the top edge. I bolted it to a heavy board, and put a wedge under the wheel (to keep it from moving).
That’s brass holding that short piece of tubing to the wheel well.
Then I slipped the blade into the other small piece of tubing I brazed onto the wheel, and bent it down, using my weight, and holding onto the end of the fork blade. It took a few pushes, and all of my 165 lbs, to get the bend right. I went back and forth to the drawing after every push to check the progress. After I was satisfied, I bent the other blade to match. I was concerned that the blade would turn sideways during bending, but that didn’t happen. I would have liked to have a formed channel to bend it against, but the flat surface of the wheel seemed to work just fine. This shows the top of the wheel. The short piece of tubing brazed onto the wheel comes from a middle section of a junk fork that I had.
I cut away the first inch of the tip, to get to where the bend started. That made the rake look more graceful, carrying the bend all the way to the end. Here, the tip is fitted to the end, prior to brazing. Not much rake was required here, since the crown was already bent 3 degrees. Look at the faint pencil lines; there is 20mm offset measured on the board. Notice how the curve extends to the tip. Most forks are bent with the dropout already attached. This leaves a straight section near the dropout before you get to the curve. It makes the fork look “kinked”. It’s a small detail that most people don’t notice, sometimes even when you point it out to them.
Here the fork dropouts are brazed on with brass, held in place by a bolt-on front axle. I used 3/32″ brass rod to bridge the gaps next to the dropouts. On the rest of the frame, I used 1/16″. The other ends of the fork blades are slipped into the crown, but not brazed there yet. Brazing the dropouts like this assures me that the wheel will fit well when it’s all finished.
I cut the tops of the blades until I got a good fit with these long reach brakes and pads at full extension. Actually having a long reach brake set up in there is much easier than relying on measurements only This will give me lots of room for fenders. I need them since I live in Portland, Oregon now. Notice that the blades are not yet brazed to the crown, but just sitting in the slot.
Does it look straight?
I am about to braze the fork blades to the crown. I probably should have made a jig for this step. The wheel has to be absolutely in line with the steerer, and the fork dropouts and crown have to be perfectly parallel. Also, the intended rake (of 40mm) has to be right. This is a very important step!
Well, I went ahead and brazed it up without a jig anyways. Extra silver can be seen lumped up along the side of the joint. The experts can braze this up and have a nice crisp edge. I am no expert, but the joint is sound. I made every effort, using heat, to move the silver deep into the joint. It’s difficult to tell when you have enough silver in there. I would have extra on the edge, trying to move it into the joint, but the space was probably already filled. Since I had practiced a lot with tubing already, I felt confident that it had good penetration. However, the only definitive way to tell is to wait till it cools, and cut it up with the Sawzall, and I don’t want to do that!
The rake ended up being 42 mm, a tad longer than intended, but that should be fine. . Unfortunately the blades were about 2mm to the left of the centerline. This made the bike pull to the right slightly when I rode it. It was noticeable at first, but easily forgotten unless I rode with my hands off the bars. I could do this, but I had to lean a bit for compensation. Of course, I had to fix it…
How I learned to Silver-braze:
I got a 1 1/4″ .058″ cromoly tube from Aircraft Spruce. Then I cut 1″ off it, and cleaned it out on the inside with sandpaper. Then I put it over an externally sandpapered 1 1/8 .035″ tube. The amount of space between the tubes (about .004 on all sides, – a sloppy fit) was about right for brazing with silver. I put silver flux on both tubes, where they met.. Next, I heated it up with the #3 tip, until the flux looked clear. I placed the 55% silver wire against the joint, heating the wire as well as the fork crown, and watched it flow inside, between the tubes. I alternated the flame between the joint and the silver wire to get the flow started. I know it made it through, when I saw it come out the other end, 1″ away. I learned how proper movement of the torch made this possible. There is no substitute for practice. I made every effort to avoid getting the joint too hot. If I see any red at all with my goggles on, it was too hot, and I put more distance between the work and the flame. When the flux gets black, it’s cooked. Ideally, the work proceeds quickly and the flux stays clear. Afterwards, I cut it up with the sawzall, and looked for gaps between the tubes.
Silver can also be used to braze narrower gaps, like .003, or even .002. Brass seems to need at least .004 to flow into the joint well. A .058 wall tube that you may buy form an aircraft supply company like Aircraft Spruce can accept a tube inside of it that is 1/8″ smaller in diameter (this inside measurement of tube is actually .009 larger than the tube you insert into it), and you will have the .0045 gap all around, that you will be able to to braze with silver or brass.
Brass melts at about 1600F; silver at about 1100F. Both will make a strong connection, but silver is easier for using in lugs, and small part braze-ons. Brass can be used for brazing lugs, but it is more difficult to do, requiring much more heat as well. Brass (or low fuming bronze as it is called) should used for building up fillets.
It is easier to use silver for lugged construction, since it flows so well, and the joint doesn’t have to get so hot. The area can be heated to a temperature just before it starts to get a dull red, and the silver will start to flow in and fill the joint. With goggles off, a dull red may be seen, but with the eye protection, you are unlikely to see any red. The silver flux becomes clear, which is the signal that it is up to temp. Brazing without any goggles can be damaging to the eyes, so make sure you get some brazing goggles. Clean surfaces are more important for a silver joint, since the lower temperature will not burn away as many impurities, like brass brazing will.
Brass can also be used to braze lugs, and is preferred by some builders. The joint has to get RED HOT, and you can see the shadow of the brass flow into the joint as you heat it and apply the rod.
Small parts like cable stops, are best brazed on with silver, since silver is plenty strong, and chances of overheating the thin wall of the tube are much less. On small parts brazed to thin tube sections, I frequently use my hardware store propane torch. I don’t need to use goggles with that, so I can see better, and not as much heat is needed. Other silver wires, like 45n, melt at slightly higher temperatures, and are better for filling bigger gaps, like at the dropouts.
I had to straighten the fork….
My friend lent me his Park fork alignment tool. I put it in the vise, with the fork in it. I slipped a 1 1/8″ .058 tube over the steerer. On each fork blade, I wrapped a towel and put a 2″ diameter “cheater bar” over it for leverage. I sat on a stool, put my foot on the vise, gripped both left and right bars, and pulled hard. It took a few tries to bend it 2 mm. This was one strong fork! I had straightened many forks in by bike shop days, and this one was the hardest. The crown is very strong, and the blades seemed stronger than they need to be. Next time, I will get blades with a .9mm wall. I repeated the maneuver on the other blade, and checked it with the gauge. Now it was in line.
However, when I put the perfectly dished wheel in, it was slightly off center. The center of the tire was just to the left of the brake center bolt. I was dissapointed in myself; there was no other way to achieve alignment than to file the dropout a bit. I used a round file, and it only took 10 strokes, but it’s kind of like admitting failure and cheating. Next time, I will make the effort to construct a fork jig.
For initial cutting of the tubes, I used aviation tin snips, which gave me a rough “fishmouth” shape. I refined it further with the grinder, and then the half round file. After some filing I would put the headtube against it and look for gaps with some backlighting. Then I would check the angle against the drawing. My goal, which I didn’t always achieve, was to have not even a thin crescent of light visible in the gap.
Cutting with the tin snips was easy on .035 wall tubing (.9mm). It could be done on the next thicker wall (.049) but was hard to cut. Thicker walls than that, and I just used the grinder to form the initial fishmouth shape.
I used an art matte board to make the life size drawing of the frame, working out the head angle, seat angle, and bottom bracket height ( or “drop” of 7.5mm from the wheel axle height as it’s measured on the drawing). For angles (73 for head, 72 for seat), I used an office supply store protractor. The board is 40″ wide, so the wheel centers went off the drawing a bit since the wheelbase ended up at 41 1/4″. I carefully took into account the fork length I wanted (long reach brakes at full pad extension). There is a line you can’t see that represents the front brake bolt, and another above it for the bottom of the head tube. They take into account the fork crown measurements and headset stack height. I didn’t do any trail measurements, since I know that a rake of 40mm or so would work out fine here. The slope of the top tube was however low I could get it using my 320mm seatpost at the max height mark. Top tube length was measured from center to center, as if the tube was parallel to the ground, like on a classic bike, and was 23″. When I finally put the tube in, I simply cut it to fit the space that existed between the aligned headtube and seattube lug. Seat stays are not even drawn in, since they will simply be cut to fit, after the chainstays are brazed on and aligned. The most important cuts and brazing would be undertaken first. The headtube/ downtube connection (hockey stick) was critical for the proper head angle and bottom bracket height. Any mistake here would affect everything downstream. Not that it’s a huge deal though. I could live with a bike that has a shallower or steeper head tube angle by a degree or 2. Heck, I may even like it better.
In the photo above, I’m holding the downtube/headtube connection together and comparing it to the drawing. It had to be as accurate as possible. This is the one joint I don’t want to have to cold-set. Trying to straighten it could ovalize the headtube. Look carefully; you can see the circle that represents the bottom bracket. The lines representing the main tubes aren’t visible in this photo, however. I mitered the downtube so that it matched the drawing exactly, when fitted over it.
Here is my drawing 10 years later. You can see the original drawing I used to make the bike (click for bigger version). If you look at it upside down, you will see the plan for a small wheel bike, superimposed on the first drawing. Framebuilders recycling.
Here, the headtube is resting against the downtube, with another tube inside it, weighing it down and balancing it firmly against the downtube. This is a technique I use for lots of bike frame joints, and it works very well. I moved the rather heavy balancing tube back and forth until the weight was centered and it was stable. Having extra tubes of various sizes laying around the shop was very helpful at times like this.
I put a spot of brass on each side of the joint first. (It’s better practice, however, to spot the top and bottom first, since a tube can twist a bit while the first spot cools when done as in the above picture. Also, it is better to use more flux than in this picture; paint it down the tubes another couple of inches) This held it securely enough for me to be able to remove the balancing tube. Next, I checked the tube angles against the drawing- it was spot-on. Then I clamped it by the headtube so that the down tube was vertical, with the non-brazed end upward. This would put less stress on this tenuous connection while I heated the joint up again. Then I went around the joint, “tinning” it…. putting a thin layer of brass down, making sure it flowed into the edge where the fishmouth meets the tube. I’m not building it up yet, just trying to coax brass in there where I can’t see. One should practice with tube scraps. You know you have it right when you can see a small fillet on the inside of the tube. Good preparation (removing burrs, sanding well even on the inside of the fishmouth) helps. That said, I don’t think most of my joints have internal fillets all the way around, and a good external fillet joint will hold together just fine without help from an internal fillet.
Brass fillets: Testing
Initially, I made many joints, improving as I went along. Each joint I would test, by bending it to failure. In all my tests, the joint deformed, but held without peeling away, and the thinner walled tube bent close to the joint. This told me that the joint was good, and that I must be on the right track.
Fillet size: It seems to me that the size of the fillet does not need to be very big. If the tubes have 1mm wall thickness, and the root depth (surface of the middle of the fillet to crotch) is 3 or 4mm, that should be more than enough. The brass is about 65 psi strength, and the tubing is 110 psi strength (for this nonhardended tubing).
I built this frame with “low fuming bronze” rod (1/16″) and Welco #17 flux which I got from my local welding supply shop. Now I use Henry James Gasflux rod and paste flux. It performs noticeably better, and my fillets improved since switching.
Here is a joint (of the handlebar stem) that I think came out okay. Little pits are visible, where flux and impurities probably bubbled up to the surface. Some ripples are visible. My control of the flame is adequate, but far from exemplary.
One way to improve the joint would be to use the Gasfluxer. It puts flux in the flame itself. I can’t justify the expense though, as I build only one or 2 frames a year .
Finishing the joint with a Dynafile would make it look pretty. These costly tools have a narrow sanding belt that whirs along a tip, kind of like a chainsaw. They eat up the brass, but are easier on the steel, but undercutting the joint (abrading the steel tube) is still a possibility. With this tool and lots of practice, one can create very beautiful fillets. But the beginner should question whether (s)he should finish the joint at all. Undercutting into the steel must be avoided, and this takes practice to do right.
I wanted to make a lug for the seattube, where the top tube attaches. This would provide extra beef for the seatpost clamp, and at the seatstay junction too. I used a piece of 1 1/4″ .058 tubing, which I purchased from Aircraft Spruce awhile back (for my folding bike project). It slipped over the tube at the butt; I had the tube extending out of it a few millimeters. The seat tube was a 1 1/8 AVR (mt. bike type). It would take a 28.6mm post (common mt. bike size). I cut it so it would have a front and rear tang that would point down the tube.
Here it is ready to braze. I will use brass, since I intend to use brass for the top tube to seat tube fillet, and the seat stay connection. If I used silver, it would all melt away during the brass brazing. (Update: actually, silver would work fine. It would not be melted away during brass fillet brazing over the top of this joint. I should have used silver)
All brazed! I’m not sure how well the brass flowed inside. It was difficult to carry it thru to the top, so I added some brass from the top. The fit probably wasn’t sloppy enough for brass brazing; silver would have flowed better. Next time I will use silver, since brass brazing over a silver brazed sleeve like this will work fine.
I mitered the seat tube (making sure it was the right end; the butted end). I needed to check it so that it was absolutely square- 90 degrees angle. Using a #1 torch nozzle I tacked it, I put dabs of brass at the “lips” of the fishmouth first. Then, I tinned lightly all around, making sure brass flowed into the crotch of the joint. The downtube and chainstays still need to go on, so I can’t build up any brass there yet.
To see what end of a tube has the long butt, you can balance it exactly in the middle of the tube on a knife edge. The heavier side has the long butt.
This is the mitered downtube where it will connect to the bottom bracket. It has a “double” miter. The main one is where the bottom bracket meets it, then there is the cut where the downtube meets it.
How I learned to miter: It all comes down to practice. Using the aviation tin snips saved time at the grinder. I had 3 different sized half round files. I went back and forth; filing and holding the tubes together, looking for gaps, and trying to eliminate them… all while fitting the tube at the proper angle. When the opposite miter was finished and brazed, I had the added requirement of getting the tube length right, and making the miter perfectly parallel (or perpendicular, as in the bottom bracket to downtube miter), in addition to all the rest of it.
I cut my hand badly on the sharp ends once; now I wear gloves. As you angle the file, the shape of the curve narrows. File strokes are supposed to be one way (away from you). Again, practice is the key for good miters. You need to do it and learn from your mistakes.
Above photo is the miter of the down tube, where it meets the bottom bracket and seattube area. It is a very important and time consuming joint. First I had to miter it against a spare lugless bottom bracket that I had (the other one was already brazed to the downtube). It had to be square with the bottom bracket, and at just the right length. I compared it to the drawing frequently.
After I was happy with the length and bottom bracket fit, I had to cut another miter in it for the seattube. I would file some, and then lay both tube assemblies against the drawing (with some spacers underneath the smaller tubes). When I saw no gaps, I cleaned it with sandpaper and set it up to braze.
There is a lot going on in this photo. The seat tube with its bottom bracket attached, is balanced against the downtube. One heavy tube above it provides a counterbalance A smaller tube inside the bottom bracket aids with balance, and provides a way to check for square. Below is another image of the same setup.
Make sure that the left-hand threads of the bottom bracket will be on the right! I had to learn to be careful the hard way, a few frames back… The F you see on the tube is my note for “fixed cup”.
Another shot of the setup.
I measured the distance from the top of the head tube to the top of the seat tube. It had to match the drawing exactly. That is pretty much where it was when I did this setup, because of my careful miters, but I had to adjust it a bit before brazing. I anticipated a some cold setting afterwords. Also, I got a visual line up of the head tube and the seat tube. I had to climb up on a ladder to look down and make sure they were lined up and parallel. I gently pushed the tube in position.
When I was finished fillet brazing, I did have to cold set the seat tube to come into parallel with the head tube. They were just a bit off when I sighted them with one eye closed. I clamped the lower part of the seat tube (close to the bottom bracket) in my bike stand, slipped a spare tube over the head tube, and pulled hard. It took many pulls to get it right, and a lot of force. These tubes are really strong. They are the modern day equivalent of Columbus SL.
Afterwards, I had to pull the seat tube away from the head tube about 1/8 inch. This measurement needed to be accurate, as it would reflect frame angles. This pull was pretty easy, since I already had plenty of leverage due to the position of the tubes, and I didn’t need to use any “cheater bars”.
Now I needed to fit the top tube in the space provided. First, I cut the top tube on both ends with the sawzall, so that the butted ends were about equal. Then I mitered the end that fits against the seat tube lug. This took about 10 minutes. I had spare 1 1/4 tubing to check it with (that’s what I made the lug out of). As I filed away, I would check the angle against the seat tube here.
Mitering the front part of the top tube against the head tube took much more time. I had to get the length of the tube just right, as well as the miter. If I cut too much off, I could only start again with a new tube. So I was very careful, and when things were getting close, I would file only a few strokes before I checked the fit again. Notice how I have it against the drawing here.
When I began brazing, I fluxed everything well, and tacked both ends of the tube first with a good sized dab of brass. That would keep the tube from moving as I started to lay the fillets in.
Looks like this came down strapped to a meteor. When I put brass down here, much more heat was required against the lug than the top tube, since the lug is so much thicker. I pretty much put all the heat on just the lug; enough of it went to the tube to make them equally the right shade of red.
After this picture was taken, I fluxed the joint and lay the end of a file down against the short tube to keep it there while I brazed. Not much pressure is needed to keep the pieces together as I start to braze. But if there was nothing to hold it there, the tube would probably fall off or move as I started to apply the brass rod.
This is the 1/2″ .058 cromoly cross tube brazed against the seat lug, and you are looking down inside the seat tube. I was generous with the brass, which holds the cross tube in the lower part of the photo. The seat stays would attach to the cross tube, and a seat binder bolt would go through it.
The seat tube must be reamed with an adjustable reamer. Distortion has made it impossible to put the seapost in without using a hammer. Maybe you will be lucky, and not have to do this. But it’s nice to have a good fit.
The seat post needs to fit in easily, but with no play. I used cutting oil, and turned the adjusting nuts of the reamer about 1/8 turn for each new cut. When I was getting close, I would always check the fit of the intended seatpost after each cut. Reamers cost about $50, and can be found at tool supply shops.
I had a spare lugless bottom bracket that I used to set up the chainstays. First, I mitered the chainstays where they fit against the bottom bracket, getting them as close as I could. Then, I cut them equal lengths (for an 18″ chainstay length), and mitered the end that fits at the dropout (they are “Breezer” dropouts, purchased from Nova, see the 4th photo down).
The proper 135mm spacing is drawn in pencil on this flat piece of plywood; I used the drawing on this plywood to line it all up.
I needed to crimp the inside of the chainstays to provide extra room for fenders and tires. I drilled a 7/8″ hole in a piece of redwood, and sawed it in half (the stay is 7/8″ at the fat end). Then I placed the tube in the channel, and put the dents in it, using the item in the photo above (which I found on the highway on a bike ride). It has a rounded shape that worked well with this task. I put a piece of cloth first aid tape against it in an effort to keep the dent smooth.
After all that mitering and denting, I have the tubes together, braced at the bottom bracket, and held with bricks at the dropout end (bricks are on the right), and finally, a short chainstay bridge at the proper distance in the middle. This bridge I tacked in place; then removing the assembly and brazing it all around on both sides. I ended up with a pretty accurate chainstay assembly, held together by the chainstay bridge. There is some sheet metal there to keep a fire from starting on the plywood when I did the tacking.
Next, I put the dropouts in a properly dished wheel, and lined them up together, and tightened the quick release. Then, I placed it on top of the already mitered chainstay assembly, checking for alignment. It was perfect- the wheel was right in the center. So I tacked the dropouts in place along the outer edge, removed the wheel, finished brazing, and this is how it looked. I removed the rubber seals from the hub first, but grease boiled out of the hub as I was doing the tacking. It’s a spare wheel I just use for framebuilding now.
This Breezer dropout allows one to simply miter the tubes against it and braze. There is no slotting like the standard dropouts. Also, you don’t need to flatten the inner chainstay in the area next to the freewheel cog, to get the required clearance, which is something one must do for the slotted dropouts. Salsa makes a similar dropout.
Okay! Now I am checking for the alignment of the rear wheel with the top tube. The rear wheel with it’s chainstays are balanced; resting on top of the bottom bracket. I would put a straight edge in front of my line of vision to make sure. It is off, as you can see in this photo. I filed the left (non-freewheel side) chainstay where it meets the bottom bracket a bit more, and finally got it centered, so that the wheel was directly in line with the top tube. After brazing (if I had to) I could always cold set these tubes, in reference to the centerline. But I couldn’t change the chainstay length. With these vertical dropouts, I had to get it right. With horizontal dropouts, it wouldn’t have mattered as much, since the wheel can be adjusted after it is fitted in.
Now is the time when I braze the chainstays onto the bottom bracket. I put the wheels on the bike, and I have the fork installed with the headset. The wheels are on with the tires inflated. I have a clamp holding the chainstays against the bottom bracket. The piece of wood props up the bottom bracket so that the center of it is 10 1/4″ from the ground (or flat board, as is the case here). This will provide the proper bottom bracket drop. The tires chosen are the smallest width I intend to use, so a larger tire would result in a higher bottom bracket. I checked the alignment of the rear wheel with the seat tube- and it looked exactly parallel. This is my last chance to change the head tube/seat tube angle, at the expense of the bottom bracket height.
The angles looked accurate, and the miters looked tight, and the rear wheel was aligned properly, so I prepared to braze. I fluxed the whole area well, and brazed the outside of the chainstays to the outside edge of the bottom bracket, making sure brass flowed into the crotch of the joint, but not building it up yet. Then I carefully took the wheels out and positioned the bike for completion of the chainstay brazing (with the chainstays pointing up to minimize gravitational forces on the presently weak connection during reheating). I lay down fillets at the chainstay/bottom bracket joint, and I finished the seat tube brazing where it meets the bottom bracket at the same time.
When it was all done, everything was is good alignment, and I didn’t need to do any cold setting. The installed rear wheel was in excellent alignment with the seat tube and top tube. Again, I just eyeballed it with a straightedge held against the wheel.
Now all I had to do was to cut, miter, and drop the seatstays in the space provided. I cut them a bit long,, and mitered the end that fit against the seat cluster. I did this for both of them, making sure they were equally spaced apart, and with enough clearance for my intended tires and fenders.
How I learned to brass braze: I learned that the brass follows heat and gravity. In time, I had a feel for the proper tube temperature by the red color of the tube, and the appearance of the flux. If the brass did not flow easily onto the tube, the tube was not hot enough. If it sizzled and danced, it was too hot. I could make a little of it go uphill by moving it with the heat, but for the bigger fillets, I found I needed to arrange the tubes so that the brass could lay down and rest with the help of gravityl. This had me moving the tubes around as I was brazing, and it made having a bike stand rather invaluable.
First I got my tanks and Victor torch, with a 00, 0, 1, and a big #3 tip. The 00 I used for braze ons, and small tubes. The 0 and the 1 I used for main tubes. The 1 I used for the bottom bracket area; a bigger tip with more heat made it easier there. The #3 I used for a big flame to heat bigger castings, like the fork crown, and I held it back further than usual (like 3 – 5 inches). I started with hardware store flux-coated rods first. The flux from those rods was really hard to remove. Then I got some Welco #17 flux that Mr. Patereck recommended, and used 1/16 bare bronze rods. .This left a residue that was much easier to remove, with a 10 min. hot water soak and a wire brush.
Later, safety became important, and I installed a fan, pushing fresh air into the work area so I would breathe less fumes. I would have a hose turned on and ready to put out a fire (that never happened).
Just like mitering, brazing takes plenty of of practice. There is more than one “right” way to do it. It is considered to be easier to learn that TIG welding. Since you need to do at least some brazing on a frame anyways, you could just as easily use brass for the whole bike. Using lugs is an excellent construction method also, but more time consuming, and limited to finding the desired lug, with it’s size and angle.
After finishing the seat stay installation, I started work on the brake bridge. This is a brake bridge I got from Gaerlan. Putting the brake bridge in was easy enough, but time consuming. First I cut it down (it was quite long). Then I mitered it, and kept mitering until it fit in the increasingly narrow space, as I moved it upwards. The pads of this long reach brake at full extension needed to be at the right place on the rim. The brake was left in place, acting as a jig, while I tacked the brake bridge. I removed it to complete the small fillets around the bridge.
Looking into the seatpost opening you can see the results of what a rather dull reamer will do– there is some scoring visible. More patience with smaller adjustment increments and extra cutting oil could have left a smoother result, too. The clamping strength will be adversely affected, but not enough to make any difference on this bike.
It’s going to need a long bolt to clamp the seat post. I cut the slot with the angle grinder, and will drill a small hole at the base of the cut, for stress relief.
The brake bridge is crooked- how did I let that happen?! I suppose the brake being in the way during tacking obscured my view. It’s not noticeable with the brake installed, though.
The seatpost clamping is really solid, and I can’t see the slot coming together at all when I tighten it. I had one frame where the seatpost clamp deteriorated under pressure, and the ears met without holding the post. That will never happen to this one. The side of the seat bolt is very close to the actual post.
Making the stem:
Not sure where I wanted the bars on this bike, I decided to make an adjustable handlebar stem. The bars are easily pushed forward or back, and securely locked in place. Height is achieved by clamping this higher or lower on the fork steerer, with spacers above and below. It’s rather heavy, at 3/4 lb. with the bolts.
I got the tubing from Aircraft Spruce, which quickly sends me whatever I need in a few days after ordering. The main stem is 7/8, .058. The clamp that fits the one inch threadless steerer is 1 1/8 .058. The short piece of cut tube that holds the handlebar is 1 /1/8 .049. The six 6mm bolts go thru short pieces of 5/16″ .035 tubing, brazed perpendicular against the larger clamping tube. I cut a slit in the clamping tube with my sawzall. Then I used my grinder with a thin wheel on it, to open the slot a bit more.
For the handlebar stem, I painted the sliding clamp assembly, and put a few coats of clear spray lacquer on the other part. A nickel (5 cent piece) is silver brazed onto the end of the extension tube, and filed smooth. Lacquer does not hold the rust back that long (at least a few weeks), but it looks cool since you can see the brass and the shiny steel, and this is supposed to be a temporary stem anyways.
And how temporary it is. Below is the sequence of events I undertook to make my new custom stem.
I used a 1 1/8 .049 tube for the handlebar clamp. This fits a Cinelli bar perfectly. On a 26.0 bar the “ears” may touch before it’s truly tight, so it may need a bit of shimming (like a strip of aluminum from a soda can). The 6mm bolts to hold the bar go through the short piece of 5/16 .035 tubing that I’m holding in my hand on the left. I put it to the grinder to give it a cutout that would make it seat nicely against the handlebar clamp. Then, I brazed one each on the top and bottom of the clamp tube.
The stem extension tube was made out of 7/8 .058 cromoly tubing. I don’t know what other people use, but this seems plenty strong to me and I like the small diameter of it. There was quite a bit of time involved in getting the miter right, where it attaches to the clamp that holds the steerer. I went back and forth to the adjustable one that was on the bike for comparison.
One thing I learned when making small parts is to be careful about cutting the tube to the required length prematurely. Here in the vise is the stem extension, with the collar that grips the steerer (you can just see 2 small tubes brazed to it that will accept the bolts that tighten it to the steerer) resting above it. I will tack braze it like this. Leaving the collar tube long allows gravity to help me in setting up the pieces
Now the stem is brazed to the collar. Here, I am setting up the handlebar clamp/stem extension joint. Leaving the handlebar clamp long allows me to check for square: in other words, the bars must be absolutely level when installed, and perpendicular to the extension. I need to get this right, since I look at it every time I ride the bike.
The hard way is to use a hacksaw to cut the slit in this collar/clamp. The sawzall makes quick work out of this job. This is one tool I consider a necessity, like a bench vise. Later, I had to drive a thin 4 inch grinding wheel thru it too, to open it up a bit more, so that it would clamp down properly on the steerer.
Then I cut the handlebar clamp open. Here I could see how well the brass penetrated underneath the piece of tubing that the bolt will go through. Not easy to see in the photo, but brass is present under it, and built up along the sides.
These threaded inserts for the waterbottle were purchased from Henry James. I drilled 2 holes, 2 1/2″ apart. Then I dropped the inserts in, with bolts attached to them for positioning and reference. Heating the bolts up first, I put some 55% silver around the inserts to keep them in place. I used a simple hardware store propane torch for this. The oxyacetelene would be overkill here. No overheating of the tube occurred (it never got red) but the build up of the silver isn’t very professional looking. Next time, I will do it before I assemble the main triangle. Accurate placement is easier with a free tube. Apparent distortion is due partly to the camera, and partly from my inaccuracy.
Installing the headset was impossible without the right tools. The newly brazed head tube (it was a rather thick 1.5mm wall tube, meant for fillet brazing) was a bit distorted (as to be expected), and I knew from prior experience that trying to install an aluminum headset without machining the head tube was a bad idea. Maybe if it was a steel headset, I could have pressed it in…. Also, the fork crown needed cutting so the crown race could be pressed on.
I took the frame and fork down to The Freewheel, on Hayes st. in San Francisco, and ordered a Cane Creek headset and asked them to ream the head tube and fork crown, and press the parts in.
The bottom bracket was another story. Even though it got a lot of brass and heat, the distortion was minimal. I was able to screw on the cups by hand and the installation was not a problem.
The wheels fit in perfectly, since I brazed the dropouts in place with “jigs” axle for the front, wheel for the rear).
I had a notion that the rear brake cable should be fully enclosed by the housing and clamped to the frame with something like the old Campagnolo brake housing clamps for a 1″ top tube, like in the old days. So I painted the frame without any of these split cable stops. Later, when I sobered up, I wire-wheeled the paint off, and brazed these on with 55% silver. Remembering how corrosion would build up under the housing and cable clamp, from the sweat, I figured it was a poor idea, even though I liked the clamps. Besides, where could I find any today? I used the propane torch again here.
I’m about to silver-braze the down tube shifter boss on. It’s held in place by the gravity of the end of the file. It would slip out of position and fall off during heating, if it didn’t have anything here to hold it down. Used propane torch here.
My decision to paint the bike with a brush and Rustoleum is a reflection of my view that this bike is a work in progress. I can’t yet say that I will not take to torch to it again for another brazeon or whatever. But I have to admit, it’s cheap and quick too.
I removed the flux with hot water. Parts of the frame that could not be dunked in a bucket were wrapped in hot wet towels. 20 minutes later, I wiped the area clean, and used a wire brush where I had to. Then I sand papered the tubes, and wiped everything with a wet hot rag. Finally, I wiped it down with a dry tack cloth.
Next, I got out some Rustoleum primer, and gave it two coats with a small foam brush. The next day, I mixed up some Rustoleum colors until I came up with this Blueberry color. That’s what I painted it with, in 2 coats.
The disadvantages to Rustoleum painting is that it ends up looking like hand painted lawn furniture from close up, and it’s not nearly as durable as a professional paint job.
The advantages are that it looks fine from 6 paces back (or with glasses removed), you can mix up your own shade of color to whatever you want, it’s easy to touch up, it’s cheap, and when that first scrape or gouge appears, you really won’t give a damn.