This ended up in a long thread about exhaust port decarbonizing, but I think it's worth flogging a dead horse here...
Ian, I think you might have missed the part that said "load transfer" changing with seat stays.
Lets say I'm in a super flexi seat, without seat stays. When I'm cornering in a right hander my upper body experiences a moment that keeps me upright. The force that provides that moment is supplied by the seat, and transferred to the chassis through the seat mounts on the left hand side of the chassis. The bulk of the force will be fed through the chassis tubes to the left-hand-rear bearing carrier. And like you say, the seat flexes whilst this is happening.
Now lets say we bolt a weak(ish) oval tube with flattened ends between the top of the bearing carrier and higher up on the side of the seat than the other mounts. Does it change the amount the seat flexes when I try to pull it outwards? I know it does because I can loosen the bolt at the top and feel the difference by hand. I can move the side of the seat at right-angles to its plane fairly easily (it's a VG), but in any other direction it's really stiff. This means that if I can angle the seat stay to the side of the seat, there is SOME, but obviously not perfect triangulation.
So when I'm in a right-hand bend, my upper body is pushing against the left side of the seat, but the seat can't move as far because of the additional seat stay. So what has happened? Some of the load has been transferred directly to the bearing carrier, and this has reduced the movement of the side of the seat. Additionally the chassis deflection must be less, because the load on the original seat mounts must also be less.
If you have reduced the deflection of something for the same applied load, I would generally say that it has been stiffened. I think you should have a play with an additional seat-stay and see if it feels the same to you, just on a kart on a stand.
I'm fairly confident it's not a placebo - when I've got someone to help me run the kart in October we'll have an experiment and see if I can tell whether the top seat stay bolts are tight or loose in a blind test. I bet I will, and I bet the lap times will be a tenth or two different.
Preemptive strike here: Traxtar, I know I've only been karting 2 years, and that I talk rubbish, but I CAN turn in five laps consecutive less than a tenth apart on a good day. Ian, long post I know, but if you can see what I mean here there is at least some merit in the argument.
Liam
|
|
Seat stays revisited again by 'Liam' << You are here!
