I had the stability improved on my (caution, marginally OT content!!) 1984 Trek. It was one of the era when Trek was putting a low-trail fork on a long-wheelbase frame to make a "sport-tour" bike. It was originally not ridable no-hands, but the fork was not the only problem. The "breeze pushes you over" problem was mine, as well.
1. It needed a new headset, even when new. The LBS had built it and put on a hybrid Stronglight headset with ball bearings (sheesh!) and the world's gummiest grease.
2. The frame was not straight. I had Ron Boi in Chicago do a full frame alignment, based on a cleanly faced BB. He has build successful RAAM bikes, so I think he understands combining performance with stability, and the value of a bike that rides right. The head tube and seat tube were not in-plane, the fork was bent sideways a bit, and the rear wheel did not sit in the seat-tube plane, even when dished and trued. He fixed all that.
3. He also measured the geometry, and together we concluded the trail value, 41 mm if I recall, was a bit too twitchy for a casual rider on mediocre roads. He had experience with adjusting fork rake for just this purpose, so we agreed he would bend the fork back (remove rake) about 1/4 inch to increase trail to about 55 to 60 mm. Clearly this did not materially affect other front wheel clearance issues, such as toe overlap or fender clearance.
Now the bike is a dream to ride, though heavy. It still has a lower-grade of Reynolds (alignment does not get you better tubing, alas). I can hold it on a line on very irregular roads, it goes straight, it turns a bit faster than before, and it no-hands beautifully. I can eat, adjust my jersey et cetera, wipe eyes and nose, and generally attend to minor comfort issues while moving one-handed or no-handed. I think I need to learn to adjust my saddle as I ride!
It was never a cush bike, and it is still not. Physics (and Tony Oliver in his book Touring Bikes) say that a more raked fork, especially a tight-radius curve near the dropouts, should be more cushy, but I can't prove it with this example.
I think having small adjustments made, as I did, is ok in terms of preserving a good rider like your Raleigh. Perhaps you could have a custom frames person (you worked with a fellow in your area in the past, if I recall) make you a fork to your spec, or measure your Italian fork and advise you on how it might modify the feel of your Raleigh. I can't believe it will be a poor result. Or, I could put you in touch with Ron Boi, whom I consider to be a true expert. He keeps a low profile, but does great work. I would not hesitate to ask him to look at modifying the Italian fork to give your Raleigh what you want it to have.
Ken Freeman Ann Arbor, MI
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Bianca Pratorius Sent: Monday, November 07, 2005 6:05 PM To: classicrendezvous@bikelist.org Subject: [CR]Fork rake/trail still confused
As you may know I am trying to find a replacement fork for my trashed Raliegh fork. It has mid 80's twitchy geometry. The ride I prefer is more stable than was popular than the extremes we saw during the last two decades. I like the short wheelbase it has, but don't necessarily need the cushy ride provided by forks that have lots of rake. I feel that a race bike should have just enough steering stability so that you can take your hands off the bars and sit up for a bit. I could still do that on my Raliegh because the frame was so straight, but the overall effect was that a sudden breeze could send you to the pavement. I want a bit more stability than that. I have a lovely Italian fork that features more rake, but if I am to understand correctly, that a more raked fork will provide more cush but less stability. If that is the case than I should go with a fork that has less rake and therefore more trail. Will the effect than be to provide more stability? That may be the trouble with these specialized type bikes: Any less rake could shorten the wheelbase to the point where it becomes a problem, and any more could make the handling even more twitchy. Is this understanding correct? This is where it pays to choose bikes that were designed with what you had in mind in the first place.
Garth Libre in Miami Fl.