Thems be some fine lugs! What RHM said above seems to make sense now that I put thought into it. I had previously thought the only reason to make lugs so thin was to showcase the builders talents. I never knew there was a functional reason behind it

Well, the choice of lugs to spread the load is, in large part, due to aesthetics. It's much easier, cheaper and functionally superior to weld some plates on there. But, a typical road bike shouldn't see the abuse to require that.

http://allcitycycles.com/images/bikes/defwish-fork.jpg

The idea is sound, but wouldn't one would expect a butted frame to buckle - rather than bend - on the central, thin-walled section of the tubing?

I can see straight-gauge acting as such, but not butted tubing. What's more, a heat-treated tubeset will react completely differently.

-Kurt

[QUOTE=rhm;15094802]When frames fail, for whatever reason, they tend to fail either at, or very near to, the points where the tubes are joined together. To overcome this tendency, builders make the joints stronger, and the ends of the tubing stronger, so they don't fail. If the builder reinforces part of a tube, there will be a point of transition from the stronger part to the weaker part; that point of transition then becomes the weak point, and therefore the point at which the tube is most likely to bend. Thinned lugs and lugs with long points, whether singly or in combination, are ways the builder attempts to make the transition as smooth as possible so that the force is never concentrated at one point. If the bending force is concentrated at any one point, the tube will deflect there; if the force can be evenly distributed, the whole tube can flex while under stress, but spring back as soon as the bending force relaxes.

When a bike is crashed, head-on, with enough force to bend the frame, the bend(s) typically occur on the top tube and the down tube just after the head lugs. I have seen such bends on a butted frame, where the bend is on the butt itself; that is, on the part of the tube that has thick walls. I don't think I have seen a frame that had actually bent on the lug, or even on a long pointed extension of a lug.

The gorgeous Chris Kvale and Chris Bishop seat clusters shown on the last page make no sense to me. This is not where frames bend.[/

Framebuilders' signature talent and expertise.

Plain and simple.

Their vision of a what a proper road bicycle should look like and ride like.

In the case of Chris Kvale though, we won't have to worry.

I can't imagine he will be building for many more years.

The amount of hand work that goes into his frames is astounding.

I happen to own three of his bicycles, two of which fit me perfectly.

They are absolute jewels to behold, but far more importantly, they are the best riding bicycles I've ever owned.

Bar none.

Durability has never been an issue for Kvale either.

My next door neighbor has a 25 year old Kvale touring bike that rides like the day it was built.

No, I was just curious.

Oh my my, Oh hell yes.

I don't follow your argument about durability, unless you mean these are boutique frames designed to be hung on the wall rather than ridden. Any bike that is really made to be ridden is going to have the durability issue I refer to, namely: when you hit it against a brick wall hard enough, where does it bend? I will admit to not having Kvale's expertise, but seriously, do you mean to tell me a lesser frame is going to fail at the seat lug? No, it is not. The place any frame will fail is going to be at the head lugs as I described before.

I am not in the least disparaging Kvale's artistry, workmanship, expertise, etc. My point is the fancy workmanship around the seat cluster is not functional. It is artistic.

For an experiment, try holding a cardboard tube, like from a poster, in your hands. Put one hand at each end, and using only your hands, try to bend it in the middle. You'll find you can put a temporary bow in it (much like you see the top tube of a frame doing when you apply the Park frame straightener tool), or you can bend over either end, but (unless you push it with your knee) you can't bend it in the middle.

Next experiment, try butting the cardboard tube by wrapping tape around it. With enough tape you can strengthen the ends enough that you can put a more serious temporary bow into the middle, but if you bend it hard enough for the tube to deflect, it will still deflect at the end, or at the end of the butt.

If you make a smooth transition from the reinforced area to the thin area, you allow a greater portion of the tube to flex without deflecting, thus increasing the amount of flexing force required to make the tube deflect. I'm sure that's the theory, anyway. In practice there will always be a point at which the tube will deflect somewhere, and at that point it will fail. Good workmanship can, at best, increase the amount of force required to make the tube fail.

Over reaction.

Just sayin' I dig these cats work.

A better use of our time is to read this recent interview with Chris Kvale.

http://biciak.blogspot.com/2012/12/chris-kvale.html

Nuff said.

Well said.

There is a lot that goes into engineering/ building a custom frame. As a guy who appreciates both finely crafted frames as well as purpose built frames, I should mention that the frames are basically products of the material limitations.

For me the ride quality of a conventional lugged frame/fork is the best available. I don't think a simple mixture of materials in certain ratios can produce the same result in each application. I also don't think that ride quality has much to do with effectiveness or efficiency. I like riding steel bikes but as a builder other materials, gussets, fillet joints represent new frontier with new potential results. Not everyone wants a nice bike.

I have a custom-built Charles Roberts frame. I honestly think this bike is truly amazing. I think custom bikes are better if done properly.

It's debates like these that has me convinced that carbon fiber is the best way to go. Wonder what my steel bikes will fetch scrap?

:innocent:

WOW - What beautiful bikes...