I think that there is a lot of excellent advice and comments here. Still, here is my two cents worth:
Take all the stuff off the bike that’s tied on as ancillary stuff. So now you are “down to seeds and stems”. (Hahaha — just used to love the “Lost Planet Airmen” back in the Cretaceous.) Then do what I call the ‘Randyjawa frame test’. (Randy is a veteran member and owner of the “My ten Speeds” web-site.)
String the bike up on a horizontal plane: you string the rims, and hang the bike on a overhead horizontal plane. (Cuz I live in Japan, I use a laundry drying pole … only the super-rich use clothes dryers here).
Now, if the alignment is off, the head will swing this way or that. And it will be rather obvious as the ends of the bars will exaggerate the arc.
This at least gives you an idea of how bad your alignment is. If it is goes … WANG! … and whips around like a terrier on a rat, you know you have a significant issue. If it is like my Vitus, and just is always a "bit off" … IMHO … ignore it!
That being said, if I hang onto a pole at a red light with my shoes tight in the stirrup/clips … and then and let go of the bars, the head sometimes swings to the left, as indeed it does on the string-up. But, I can run a descent flat out in high gear — in traffic — and it is as steady as a rock.
I’ve strung up the Vitus in another way too — to check the alignment of the frame triangle. No problem. The big frame tubes are straight in relation to each other. But, in exception to my usual practice, I did not go to the frame maker to have the DO’s and stuff checked out. Usually, I string the frame, do some measurements with callipers, and then give the frame guy my numbers. I let him decide decide what is practical to correct and align. But I always insist on aligning the DO’s and tooling the head tube. Im my experience, the DO’s are ALWAYS out of alignment on an old frame. ALWAYS!
The Vitus is an epoxy, bonded frame. So I abandoned my usual practice. (My opinion — don’t ever torque on a vintage, bonded frame.) The wheels slide in and out like silk, so perhaps all is well. Still, that area is suspect. But, then again, I do know the bike had one crash in the mid 90’s that ended the racing career of the former owner. So, for reasons I will abridge here, I suspect the head tube may be very slightly off — but I can’t see it. And I’ve not yet been able to measure it — yet. (As with the DO's, it takes time and effort to check them, and I cannot change them anyway, due to the virtually unique nature of the frame assembly that was done by the French aerospace industry decades ago — 'Sud Aviation'?)
Over the years, I have finally managed to ride it for seconds with hands off, but I know that something is not perfect. What exactly? The wheels are perfectly centred and dished.They have been in the expert hands of an ex-racing mechanic. I’ve been setting hub bearings since I was 12 years old. The Mavic 310 competition headset is a very rare gem that I took infinite care with during my rebuilding process. So ….
THE FINAL ANSWER: AGE! Vintage bikes may have little tweaks and turds. We can obsess over them, but in the end we can accept them because all old machines — no matter what they are, be they bilkes, airplanes cars — have them. Get the basics right, and then just ride the bike — my heartfelt advice.
I have other old machines — take my Simplon/Romani: it hangs perfectly straight on a modern, Shimano factory wheel set. I let the frame maker pull and bend it around a bit before I built it up. Hands off … no problem. I love the thing. But riding my Vitus is just bloody marvellous. After a ride I relax in a deck chair, have a drink, and just stare at it in wonder.
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Vitus 979, Simplon 4 Star, Gazelle Champion Mondial, Woodrup Giro, Dawes Atlantis
Last edited by Lenton58; 08-11-14 at 08:52 AM.