bicycle handling : short trail plus stabilizer spring compared to longer trail
I thought I'd post this in the framebuilders forum as the question is very geometry-related. I'm not an experienced enough rider to be able to discern differences directly unless things are pointed out to me.
I have two bicycles I'm comparing; for my size, one is 78mm trail (marketed as a general purpose hybrid), the other 46mm (front-rack light cargo bike) but has a spring between the downtube and fork fender mount, acting to pull the fork back to center. I only really noticed the resistive effect when the fork is steered over 40 degrees away from straight; I'm not experienced enough to tell if there was some effect at gentler steering angles. The obvious reason for the spring is to help the included bipod kickstand to work, but it has to affect the ride as well, yes?
I generally read that short trail leads to more maneuverability ("twitchiness") but would the effect of the spring generally make the bike handle as if it was longer-trail? Or is the effect much different? I can imagine that at small angles the spring doesn't elongate enough to produce an effect.
My uneducated guess now is that the spring makes a short trail bike behave short trail at small steering angles, and ramps up quickly to long-trail-like at higher steering angles.
I'd appreciate if someone could comment on the above and let me know where I'm right, wrong, and just missing information.
The spring will have a small influence on handling, but while riding the fork doesn't generally move that much. Most steering is done by weight shifts. The fork is mostly important at very slow speeds. At small deflections, the spring will have no effect, bike will still be twitchy without a load.