Joined: Feb 2012
Posts: 19,344
Likes: 5,461
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
"
A worrying prospect..." oneclick
And a step in the process that goes on in pretty much every bike factory when making a frame. IMO the question isn't "did they" but "How much was needed", which we'll never know.
The first thing I thought of is opposing small flats did serve to aid the aligning process, or maybe the measuring aspects. When I am measuring main frame twist I want to have the contact points (of the feeler or dial indicator tip) as far apart (upper to lower) as possible to increase any deviation amounts WRT the seat tube. But the surface right around a lug's shoreline can be "lumpy" of sorts. Brazing filler residue, too aggressive filing and that heat distortion thing all combine to make the surface not so "flat" after all and the lugs might have not been filed equally thin. To help increase the measuring contact points far apart and rely on the head tube's ID (where the fork is) I have a shaft that goes through the HT and had same diameter end cones loaded against the lug faces.
I can see a person filing down the two flats so they have the same thickness, relative to the reamed ID. Then when aligning the feeler pointer contact is in the same place, the same distance from the HT axis and is as far from the other end as possible. Seems like a lot of work to avoid having a tool that might need to be used with pretty much every frame the factory makes.
So here's a story. (Yes, I am full of them. And I make little claim of being correct
). I worked for Geo. Rennie Bicycle Shop for about 7 years back in the later 1970s/early 1980s. A pair of childhood friends started the shop on one's back porch and after a couple of decades grew to be the service and "pro" (as racing sort of existed back in the 1960s/1970s) shop in our area. We sold Raleigh, Peugeot and Motobroken as our main lines when I started. Remember this was just after the first gas shortage I was an adult during. The shop sold a zillion bikes (some funny stories about this but not the one I am taking too much time writing right now) and both Raleigh and Peugeot had invited select US dealers to their factories for tours and hand shakings. Again, there are stories about the Raleigh factory (involving TDC freewheels and 531 decals) but it was the Peugeot factory tour that Jack (George's partner) told me about that pertains here. At the end of the frame brazing "line" there was a pile of raw, just brazed, frames and a guy would pick one up and (with respect to the Taylor Brothers across the channel) sight down its length. As needed he would pick up a huge leather covered mallet/hammer and whack the frame this way or that way, as needed and confirmed by his very experienced eye. No lasers, surface plates, dial indicators, feeler gages.
I don't remember if Jack or George ever got to tour the Motobroken factory(s). We dealt with more Peugeots than them and Raleigh was 2/3 our total sales so we didn't see many high end Motos. Too bad because I felt my Super Corsa was one of the sweetist handling road/race bikes I have ridden. Andy
__________________
AndrewRStewart