Brian's Bike

I got a nice start on Brian's road bike today. This is going to be a stable race bike with a bit longer (than typical) wheelbase, a bit lower and stable steering. I'm using a double-oversized tubeset here with thin walls. Its amazing what the suppliers are doing with some of the newer high-strength steels...

I've had a few people express an interest in learning a bit more about the process of transforming a pile of tubes into a bike so on this build I plan to post some pix mid-sequence. You can follow along on Flickr under the "Brian's Bike" set.

I spent a bit of time working on the lugset this morning. This lugset has decent lines and certainly could be used "as-is", but I thought it would be nice to sharpen things up a bit. I made the biggest changes to the seat lug. Since this bike won't have mitered seat stays, I chopped off the back and gave it lines to mirror the front. Sometimes, I cut details into the lugs using a really small jewelers saw. This allows me to make really tight corners and super small features. For this type of pattern, though, a large half-round file works best. By using even, light file strokes the curves seem to come out smoother than my sketches. Perhaps no one will ever notice the difference with the new lines, but I don't care...to me its the little things that give each bike their own personality.

The past few bikes have been built with a completely new workflow. I think this bike is already showing the benefits. On earlier bikes, I would build small subassemblies on the fixture slowly integrating part after part. At each step, I would check the parts on the surface plate to make sure that everything was going well. This worked ok, but by putting these pieces together I missed the opportunity to balance the fit of all of the parts at one time. Building a lugged bike is sometimes a negotiation. Since each lug is designed to fit a nominal angle, I'm always working on figuring out the how to best fit things together. This can mean filing, grinding and even a bit of "blacksmithing" to make the fit just-so. Silver brazing works through capillary action...if the gaps are too tight or too loose the silver just won't flow.

In my new process, I've placed my fixture right on the surface plate. In this orientation I can check the alignment of the tubes so that things line up perfectly. Since I spend a bit more time fitting up the whole front triangle, I also get to play with the fit of the lugs even more. When everything is perfect the bike is pinned and quickly tacked together and then brazed outside fixture.

to be continued...