Saturday, March 13, 2010

Lug Shape Help

I need your help! Faced with the prospect of actually having a shop to build bikes in (we'll be brazing in the next week) I'm beginning to go a bit mad. I spend my spare moments drawing lug shapes, speculating on methods for bilaminates, deciding that I need to make my own lugs from scratch, etc. That envelope is only one victim of my madness.

The biggest debate I'm having right now is which lugs or construction method to use on my next frame, which will be a randonneur. I recently carved up a set of Prugnat lugs quite dramatically, and I think they look nice. But they don't quite say "randonneur" to me. For a road bike they'd be perfect—I can imagine a green bike with these lugs masked off and painted yellow, with red logos... But anyway, for a randonneur that will be painted black they just seem a bit flashy and angular.

This thought set me off on all sorts of researches. First I thought I would do bilaminated joints on the headtube (like on this incredible Jamie Swan), and use an investment cast BB shell and seat lug. But then I couldn't find a standard-diameter investment cast seat lug I liked enough (the Henry James is perfect except for its too-short point on to the top of the TT).

So I started looking in to making my own seat lug from scratch. In addition to giving you lots of freedom, it's good practice with fillet brazing! I was naturally led to the Rene Herse Bicycles website, and the glorious handmade lugs Mark Nobilette makes for them. Looking at this page made me want to make my own lugs, certainly, but it also made me take another look at the Singer/Herse lug shape. There really is something perfect about the distinctive constructeur double-swoop. But I also noticed the very un-showy shape the headlugs made around the head tube. While certainly the less celebrated side of the Herse/Singer lug shape, I appreciated its simplicity, and it got me thinking.

It brought me back to the Prugnat lugs I recently carved up. They had the same "Herse/Singer" shape around the head tube before I set in to them with the file. (The points on to the TT and DT, of course, were more Italian and long-pointed.) Suddenly this seemed to be to be a more or less ideal shape for my randonneur: not flashy, not an exact copy of the Herse/Singer, with nice long points to work with...

So I ask you: which of these head lugs should I use on the randonneur I'm about to build? The "loveable nerd" shape on the left or the swoopy avian shape on the right? I'd leave the "nerd" more or less as it is, but I would shorten the point on the underside of the TT and make it a spoon. (And I'll use the "carved" lug on an upcoming road bike if I don't use it here...)


johnb said...

While I'm not a big fan of "plain" lugs (I'm an old fart brought up on Nervex lugs and frames by Hetchins and Claud Butler), I do prefer the carved lug on the right to the boring one on the left.

AH said...

I certainly don't want to be boring :) Thanks for the feedback!

RMHampel said...

I'm with johnb here. Not exactly Hetchins fancy, but with some definite style. I like your thinking on this project. Have you seen this bike?:

It's a beautiful bike in many respects. You could certainly do worse than to emulate something like this.


AH said...

Good Lord! I had not seen this. Nice bilaminates! And a paint scheme not unlike that of my own beloved Niles. I must say, this might be a bit beyond my abilities at present, and also passes a bit in to the realm of the "fancy" for my tastes. But still, some interesting lessons to take from this. Wow!

Yes, I think I'll use my carved lugs -- the majority wins! Did I mention that they weigh around 50% of the weight of the uncarved ones? Hehe.