Originally Posted by
hokiefyd
Trail will decrease with a smaller tire diameter and increase with a larger tire diameter (all else being equal). Depending on what you want in a bike, you may prefer less trail or more trail. I generally prefer less trail, but that's a very personal preference (and trail is certainly not the only metric that defines how a bike rides).
If you're moving down to 584mm wheels (27.5"), you shouldn't have a problem with overall tire diameter. If you have 35-622 tires now, those are nominally 692mm in diameter. If you're looking for a street-oriented tire in 584mm wheel size, you'll generally find them in the 47-50mm width, which would nominally be between 678mm and 684mm in diameter. You may find that your current fenders aren't quite wide enough for tires that wide.
By low trail, how low are we talking about?
I think that the way the frame is assembled and the way the tubing is butted can easily make the trail feel different. At least this certainly is what I observed with my Trek over my old Nishiki road bike. Both seem about equally stable in a straight line or at speed, but the trek walks all over the old road bike in terms of agility. I think that the Nishiki may have had slightly less trail. My trek is @ 62mm which isn't exactly low, at least not for a bike designed primarily for use on pavement.
My current fork has an offset of 45mm. I am thinking of updating to a fork with slightly more offset to lower the trail a little.
If I understand correctly, is head tube angle mainly responsible for stability at speed, while fork offset determines agility at lower speeds? How would a bike with a steep head tube and low fork rake behave?