Sunday, January 30, 2011

Getting there...

It looks like a bike!


Plug-type dropouts need a bit of love to smoothly transition to the tube. The goal is to make it look like one piece when its painted.



I admit that I gulp a few times before drilling big holes in a frame that's almost done. I've never had any issues, but it does feel odd.

One good thing though...brazed in steel bosses not only hold the bottle cages, but they really reinforce the tube near the hole. Although they look pretty much the same, aluminum frames have riveted bosses which don't add much (if any) strength. Its highly unlikely that a steel or an aluminum frame would ever fail in the middle of the tube, but if it did, the boss location is the most likely.

Test post

Lets see if this blog to Facebook link works.

More pix from Brian's build

This is the seatstay design that I've used for the last few bikes. This is one of those areas that framebuilders use as a "signature" for their style. I don't know if this is going to be the way that I do these all the time, but its my favorite so far.

I use a really large diameter tube on a very shallow angle so that the facet almost look flat, but has a soft "scooped" profile when its done. When its done, it almost looks like a solid bar that has been cut, but its completely hollow. Often, the seatstay ends are done with a cast plug that sticks in the top of the tube. These can have lots of different designs, but they always have a little bit of "heft" that I don't like. To be fair, no one would ever know either way I guess but if I'm going to add material to the bike it had better be for a good reason.

Here is a before and after picture of the seatstay...


The seatstays are now brazed to the frame. If you look closely, you'll see small pins (1/16" finishing nails) that hold them in the right spot while they are being brazed.

Sunday, January 23, 2011

Brian's Fork

Now that I've recovered from my freak ski accident (and decided to listen to the doctor), I'm back in the shop making progress. I've uploaded some new pix from Brian's bike build, including a few images of the fork build.

There is a bit of skill to getting forks to come out well, but I think its worth it. A custom made fork is the key to making a high quality frameset. Why? A few main reasons: unlike production bikes (they work around one or two sizes), I can tailor the fit and geometry to perfectly match the frame.

Steel forks have a ride quality that is unparalleled. This is due to the fact that steel has such an incredible elastic limit, so that the blades can be designed to be as supple or firm as desired, without concern over permanent damage on potholes. The fork tubes can be switched out depending on the intended loads or use.

Custom forks are very adaptable. Bikes that have fenders or larger tires (or want the option, even) can be built with a bit more clearance. Any sort of attachment point can be added as well: disc brake mounts, rack mounts, mounts for lighting, etc.

Steel forks fail in the safest way possible. Steel is a ductile material, meaning that it will bend a LONG way before it snaps. Should the fork sustain some sort of damage (anything can be broken), a steel fork will give the rider the best possible chance of staying upright. Low ductility materials can fail very quickly as cracks (perhaps from an earlier event) rapidly propagate through the remaining section. This type of failure is particularly horrific in both wheels and forks (face, meet ground!).

To be fair, steel forks are a bit heavier than an equivalent carbon fiber fork. All things considered though...unless you are competing in an elite level event with a large elevation change this difference is insignificant to performance. Don't believe me? You may want to note that most U.S. road time trial records were set on custom steel frames with steel forks.

Saturday, January 22, 2011