wil780
Member
It might well be that we're saying the same thing. Just to be clear, camber thrust is a consequence of the different diameters of the tire at right and left sides of the contact patch when the bike is leaned over (the original topic of this thread). They try to rotate at different speeds but can't so give a twist to the contact patch. This is what turns the handlebars to the right when you are leaned to the right. As soon as the camber thrust twists the contact patch to the right the contact patch starts to slip, generating a force to the right. This force is what turns the bike. But because it is applied behind the steering axis (because of trail), it also tries to turn the bars to the left.I think what I said about the rake/trail is what you said, when I said the initial countersteer doesn't stay there. What I said was the rake/trail combination steers the bike, not that it steers the wheel.
Camber thrust is a better description of what I was trying to say, but that in itself is a result of the rake/trail geometry, I think. Compare a huge chopper with the front wheel 5 feet out there, and it can only lean 15 degrees. How hard is that going to corner? There's an ideal rake in there somewhere, you certainly don't want vertical forks, and there's the right amount of trail, too. How those affect the bike in physics is a little over my head, but I'm thinking that what I said is not quite what you thought I said, so we're on the same page.
What you described, as the rake/trail combination trying to turn the wheel out of the turn is what I described when I said that you let off the handlebar pressure and the bike stands up by itself. You do maintain pressure on the bar on the side you want to turn towards, but you don't actually maintain counter-steer (wheel actually pointed the other way) as many people seem to think. The pressure keeps the wheel from straightening, but it's still steered very slightly towards to turn direction. Only on the initial tip-in is the steering head actually pointed the other way, and once lean is induced the wheel steers back into the turn. It does want to center so you hold pressure, but you don't hold an opposite angle on the steering head. That leads to road rash.
On an ideally setup bike (for me) these forces balance and no input is needed from the rider once it is settled in a corner. On such a bike, you definitely have to lift the bike up out of the lean by countersteering. Bikes I've had that were like that were an SV650 and a CBR600RR. Since I wore the tires all the way across (I rode them only in the twisties) they stayed neutral as the tires wore. The FJR is pretty close to neutral on new Pilot Road 2s, but as the tires wear during straight-up riding you need more and more steering force to hold it down in a corner and it will lift up on its own as soon as I stop holding it down. The stock Metzlers needed to be held down in a corner even when new, and got really annoying when nearly worn out.
A neutral bike feels better to me, but I can see the point of setting it up to need to be held down in a corner. That gives you immediate feedback when the tire reaches the limit of traction and starts to slide, whereas with a neutral bike you need to detect the slide in other ways.
If you want something else to think about, consider the camber thrust from the rear wheel. It can't turn the swingarm, so it tries to turn the whole bike. I think it is a minor contrubuter to both turning the bike and (because of trail) steering the bike.
