For an Aussie, the winter frosts of rural England can be a shock. After the first few days of attending the comprehensive frame building course at Downland Cycles in Kent, however, the cooler temperatures were a wake-up call from an intense learning curve.
For a self-confessed steel bike nut, this was a dream come true. The mathematical and geometrical aspects were a bit of a struggle, I have to say, but Bike CAD makes fitting and designing relatively easy, even for a novice.
It’s the carving of steel, the alchemy of the construction and the riding that I really enjoy. In fact, for a bike nut, it’s the sort of thing that brings about that epiphany where you realize that this is the work you were born to do.
At the last installment of my visit to Downland, I had mitered all of my Columbus Zona tube set according to my BikeCAD drawing of a drop bar 29er frame with Llewellyn lugs and all the braze-ons for racks.
The Llewellyn lugs are a bulky set, so I carved in some rudimentary decorations, which would also aid the bronze to flow between them and the tube. Not totally necessary, but it would also help visually.
Bryan was an excellent teacher and stoically guided us through every step of the process. There’s a lot to take in, especially when you get down to the finicky process of cutting out gaps for the dropouts to fit into the chain stays.
Here’s my bottom bracket shell and seat tube, sans BB lug, fitted together in the jig. It may not be a watertight miter, but it’ll hold, especially once I’ve joined the two of them together with bronze.
After we’d tried our hand at brazing some bosses into some scrap tubes, testing our heat control and learning the reasoning behind flux and cleaning, then began the intimidating process of applying heat to the tubes we’ve painstakingly mitered.
Greg was ready to go first and slowly but surely, assisted closely by Bryan, managed to successfully braze cable guides and water bottle bosses into his down tube.
Sense of accomplishment yeah! You can imagine the relief and joy at having completed this first small step of the process. There’s not too much that can go wrong at this stage, apart from overheating the super-thin steel tubes and having to start all over again.
Time for morning tea.
The academy is located in Lynsore Bottom, a funny name for a peaceful pocket of the Kent countryside…
…where the molehills are actually mountains!
The light is sublime around here, and there’s any number of quiet laneways to explore. I took every opportunity to wander through them, trying to absorb the avalanche of information that we’d been instilled with.
Julie Jackson is Bryan’s enduring wife and an incredible chef who ensured there were plenty of home-cooked treats ready for us at every break. Stuart, Greg and I had plenty to discuss over a cuppa.
Stuart was next in line to hold the torch as he brazed together his pair of forks — topped with beautiful Richie-issimo decorative reinforcements.
Success. Well done Stu! Now get the file and clean those up. The trick is to try and remove as much bronze or silver as you can from the shorelines without touching the steel, which will undermine its structural integrity.
They’ll look the business once they’re cleaned up. There’s a plethora of choice available to the frame builder when it comes to lugs but, at the same time, there are limitations when it comes to the angles they offer. It’s a juggling act and you need to know your maths.
Greg was ready to tack together his frame, which will hold the tubes together in the jig while he completes the main fillets. Well done, Greg, but you’ve got a long way to go yet!
Time for a break. Thanks, Julie. Homemade sponge and a cuppa.
The English introduced a lot of things into Australia, but they could’ve kept the foxes and rabbits if they brought jammy doughnuts instead.
Right. My turn to braze my forks. Cyclocross blades and a Pacenti crown. My favorite lug ever and one of the most robust.
Rack mounts first. The legs were measured and drilled, making sure they were in symmetrical locations. Measure twice, drill once.
Here we go! Heat control is everything. The size of the Pacenti crown means there’s a lot of cold steel which needs more heat than the lugs, so I had to work the flame around the crown first to get it and the legs to the right temperature at the same time.
Once the flux starts to bubble, the temperature is at the right level. Then the rod is introduced, and capillary action draws the liquid inbetween the two surfaces. It really does feel like magic, and the process is incredibly addictive — and satisfying.
The steerer tube is a different thickness again and requires special attention. It’s crucial to take the time to make sure the bond is strong. After all, I plan on riding this frame fully loaded down a dirt track and I don’t really want the whole thing to collapse…
Done deal. Quite ready to crack a beer open after all of that.
No time to stop yet. The dropouts need to be attached, and make sure they’re straight in the legs.
The fork fixture takes care of that. Once the dropouts are done, then it’s time to clean up the whole lot by rinsing it with boiling water and getting the files out.
Greg, meanwhile, has been busy, laying down the fillets on his main triangle. Look at that! Not bad for a first attempt, but thanks to Bryan’s guiding hand, there’s a minimum of air bubbles and a whole lot of beautiful bronze.
After a whole lot of careful filing, these fillets will be a buttery-smooth transition from tube to tube — the most gratifying appeal of a fillet brazed frame. Cheers! Stay tuned for the next installment.
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Previously:
FRAMEBUILDING AT DOWNLAND CYCLES PART 1: LUG AT FIRST SIGHT
