Sunday, July 20, 2008

Day 1: Designing the Frame

Today, after an early wake up and breakfast, we headed in to the shop, where things started gently with a history lesson. We got to hear a bit about the genealogy of American framebuilding — the web of links between Doug, J. P. Weigle, Richard Sachs, Ben Serotta, Albert Eisentraut, Bruce Gordon, Brian Baylis, etc. It's a remarkably coherent family picture. This is a skill that is handed down, so this shouldn't be much of a surprise.

Next came the time to choose tubing, which satisfied the consumer in all three of us. In light of the recent Bicycle Quarterly tests, I managed to talk Doug down tube by tube from 1/.7/1 to .8/.5/.8, mixing and matching Kaisei, Zero Uno, and True Temper. Robert and Dan are using oversized tubing and don't share my Bicycle Quarterly-induced obsessions with planing.

After lunch came the fit session. Armed with pedals, shoes, crank lengths, handlebars, brake levers, and saddles, we got on the Look fitter and set it up for our desired handlebar height and reach, saddle height and setback. Robert in particular came out of this with some dramatic results: he's been riding a 57-56 for years, and now looks like he'll be riding about a 62-56 (!). Dan's even taller: he'll be on around a 65, though he's using a sloping top tube. The position I've gotten used to on my randonneur rides this summer turned out to be just right.

The last thing we did was to design the frame. A quick breakdown of what we're all making is in order. As I said in my first post, I'm building a "winter training bike" — a fixed gear with fenders, a front rack, and 700x26 Grand Bois tires. Dan is building a pretty serious commuter bike: internally geared front hub, disc brakes, bullhorn bars, Schwalbe Marathons, and probably a belt drive. Robert's will be a sport-touring bike ready to carry a heavy load. He'll use it for commuting.

My frame was shockingly easy to design. 73 degree seat and head tube angles, 60 degree down tube angle, a 65cm seat tube, and 53mm of rake, 75mm bottom bracket drop. The parallel seat and head tubes will make mitering (tomorrow's task) easier. The Henry James lugs I'm using all will fit in to this design easily, and there's no need for a headtube extension with my 6cm handlebar drop and Nitto Technomic ("short quill") stem.

Dan's was pretty smooth too: 73.5 head angle with 3 degree rake built in to the crown, 72 degree seat tube. The top tube will slope with his lugs (Llewelens), but that's what he wanted...

Robert's was a bit trickier: with only 3cm of handlebar drop, he needed a headtube extension to get the bar high enough. The Henry James lugs he was planning on using don't incorporate one, so this is where mention of using the Pacenti Artisan lugs was first made (they have a 15mm extension). Then the angles (72 seat, 72.5 head) worked better with the Pacenti than the Henry James lugs. Robert is now staring down the prospect of lots and lots of carving -- the Artisan lugs are gigantic compared to the Henry James, the idea being that they're a "canvas" for builders to show off their carving skills. Since my lugs are so simple, I've volunteered to help with the filing! These Pacenti lugs do necessitate a sloping top tube, though, which was too big a challenge to handle at 10pm, so we called it a night.

[More photos here.]

1 comment:

Ben said...

Great blog! Really enjoying a look a the framebuilding school experience....