You may have wondered why it costs so much to replace frame tubes - roughly $200 for a tube. Besides buying premium quality single tubes (Reynolds, Columbus and Deda) there's a lot of time-conusuming hand labor. We evaluate the frame and quantify that ( writing down the actual dimensions). Then we set our big steel frame plate (shown below) to the frame's geometry and lock it. Next, we remove paint from the areas we need to rework and cut the tubes. Then, the fun part. Here's a frame right after we've taken the joints apart. You can see the damaged tubes and their naked ends right next to the seat tube and the lugs we're going to save. The original head tube and head lugs are shown at the bottom of the photo. The shiny stuff all over the joints is brazing flux, a mixture of boric acid and various anti-oxidants. We add flux while preheating the joint so there's a big gooey layer of the stuff all over the working area. The flux carries away the dirt and protects the hot steel surface from oxidation. [More notes on that process below]
One doesn't normally get to peek at naked bicycle frames. Here's your opportunity!
Notice the thick translucent flux in big drips (as around the pump peg). Where the flux has cooled and cracked away, the steel below is a clean light grey color. Boric acid flux is a powder which looks somewhat like sugar, albeit tinted with some pastel color in some brands. We're using Petersen's Blue flux here. Heated, it turns to something like cold Karo syrup, flowing over the steel and floating all the dirt away. Ideally, thick black drops of consumed flux run off the work, carrying the crud with it, as new clean flux is added above the joint. That efect may be seen on the scrap tube in the upper right.This is the ugliest a bike frame can be, Follow the Frame Repair links on our Service page for more usual shots of clean and finished bicycle frames all tarted up and beautiful!
Here's the same bike halfway through its cleanup:
Here's a more typical quick frame repair. We do 15 to 20 of this exact repair every year, plus a scad of under twenty dollar minor brazing and alignment repairs like it.
Click here to email
| |