Originally Posted by UNCLECHET
Sweet bike. I think what you're really interested in on the fork is the "trail" You draw a line thru the steering axis (steer tube) to the ground. Next drop a vertical line thru the center of the axle. Measure. The greater the number the more stable the bike will be. It also won't respond to input as fast. It doesn't matter if the fork is straight or curved. It's the relationship between the steering axis and the axle.
Track bikes tend to have alot of trail (and little rake). I think that 'large trail' bikes tend to be more stable the faster you go. In the Jan. 2004 Rivendell Reader there is a short and somewhat cryptic article about Marc Muller's (Waterford) ideas on the subject. While working for Schwinn, he was tasked with creating bikes with a consistent steering feel regardless of head tube angle, tire size and rake. His efforts led him to conclude that there was another factor which he termed 'steering angle'. This is the angle formed by a line drawn from the front axle to the point on the ground where the steering axis is projected and is measured relative to the line dropped straight down from the front axle. It's hard to explain so I added it to the drawing. See below.
Anyway I found it interesting and as a point of reference, he says that a steering angle less than 9.5 degrees results in a twitchy bike. The upshot is that it may be a mistake to place too much stock in rake and trail. Anyone else read this article?
Jim