Originally Posted by
Barrettscv
My Cyclocross bike with a 66mm trail is neutral, allowing both tires to drift when exceeding traction on loose-over-firm gravel (aka ball-bearings). I notice that the front will push (to use a NASCAR term) at the beginning of the turn but that the tail will also drift as the turn continues. I try to "stay the course" or gently increase the turn radius when this happens, since changing positions or correcting the steering abruptly can lead to a fall.
I don't think the automotive use of "neutral" handling is the same as with bicycles. And 66mm seems to be fairly high rather than neutral.
My go-to reference is
Trail and Its Effects at Spectrum Cycles. Quoting:
As a general rule when dealing with 700-C wheels, a trail of about 56mm will give a frame set "neutral" handling. My use of the term "neutral" here refers to two things. First, neutral handling means that a frame set will respond to steering input in the same manner no matter what speed the bicycle is traveling. Second, while cornering, a neutral handling bike will have neither a tendency to climb out of a turn nor have a tendency to dive into the turn, it will simply hold the line that the rider sets up unless further rider input is applied.
My high-trail bike is my cyclocross-based Trek Portland. I think designers choose high-trail for CX bikes for the light steering feel at the lower speeds of cyclocross.
For the record, automotively, what we call "trail" is referred to as "caster", and is a front wheel alignment matter. While felt in handling, other factors influence oversteering, understeering and neutral handling.