Originally Posted by
unterhausen
What blades did you use for that bike? Was the crown modified?
I don't remember for sure but the blades were probably either Excel or Prestige, the extra-light (0.8 mm) model no longer available. Excel were 0.7 I believe or maybe even 0.6. I still have a pair and they're scary-light. Some "super-steel" though, stronger than Prestige.
Whatever they were, I spun them slowly in the lathe (held by the small end of course) and ground them down thinner with a Dynafile, just moving the dynafile and paying attention to how much pressure I was putting on it and how long I was dwelling on any region. With the goal of thinning the wall only in the middle, away from the (eventual) HAZ at both ends. Sort of like double-butted in the final result. Since I had no good way to measure the resulting wall thickness down there halfway down the blade, I just went with weight as a proxy for wall thickness, and stopped when I reached my predetermined goal for lightening. I don't remember what that was now, but I'm sure I stopped well short of taking half the wall off. More likely I took off a quarter or less.
Sound risky? yes of course, and too time-consuming, so I would never do this for a paying customer. Laurie was into it though, I wasn't foisting this on her unawares. She said "hell yeah" when I proposed making the lightest fork I could. My justification for it was basically "why should she have to use the same blades I used for my own fork, when I weigh literally twice what she does? I'm 95% sure the resulting fork was
more reliable for her, than my fork is for me.
The crown is a Saba, investment cast, very tiny. Then I lightened it by thinning it down from every direction, even milling a pocket down inside the blade socket. I don't know how much got turned into chips, probably not a huge amount since the crown is so minimalist already.
Builders who used them in the '80s include Glenn Erickson and Dave Moulton. Ooh here they are for sale cheap on ebay:
https://www.ebay.com/itm/254458998579
Oh yeah I also thinned and lightened the dropouts, and used an un-butted steerer. Nothing else wacky about the steerer though, I didn't thin it or drill holes in it like on Merckx's hour-record bike...
Mark B