Smitty1955 wrote:mattyv74 wrote:The effect of wieght transfer on suspension geometry is fuck all. The point of a good suspension set up is to cope with all this.
But weight transfer or weight does affect a bikes handling and you have to know how to adjust the suspension. I can't see how you can say weight transfer does not affect the suspension geometry when all the schools I have attended have demonstrated that it does.
As I see it, the challenge is to minimize the effect of the change
Ok, for those who can't read what was actually written, I'll spell it out a bit clearer. It could be long,but we'll see how we go.
Now remember this is a thread regarding back brakes and how much to use, Not suspension setup.
Firstly; A good suspension set up will cope with any reasonable input that the bike receives. Yes, weight transfer will move the weight forward, but the effect this has on the suspension geometry are all good for cornering. The front dives wich increases the head/fork angle. This WILL (100%)
encourage the bike to turn harder and tighter, no exeptions at all.
Secondly; Any of the schools, HART, Stay Upright, Aus Superbike school, and even Kieth Code's own books explain that a tyre only has 'X' amount of grip. Now consider the following:
1-A bike that is travelling in a straight line has about a 51/49% split front to back. Corner with no braking at all and the load split remains the same within 1/2% or so.
2- When a vehicle (car, bike, boat, plane) corners, you are basically trying to redirect momentum. This means that the grip required by both wheels increases.
3-When you are slowing the wieght split shifts forward, up to 80/20 when still under control,
This all means that the front tyre enters a corner having a lot more load on it than the rear. As a result the front will not take as tight a line as the rear, and it will 'push'. This IS NOT a result of geometry changes. Remember that geometry does change, but for the better. However the changes are not always great enough to overcome the increased demands the front has to deal with.
So as I wrote, weight transfer does not effect suspension geomtry. This should probably read, "does not effect supension set up
adversly."
I did not say weight tranfers didn't effect handling as I was mis-quoted.
Hit the brakes and you run wide, a little or a lot. But the explanation lies in weight and force vectors, NOT suspension geometry. If you can remember back to when you were a kid, what happened whem you hit the brakes on your push bike? It ran wide, particlarlty using the front brake. Now pushies (excluding mtb's) don't have suspension, so it cant be changes in geometry that make it run wide, can it???
The answer- A tyre has only so much grip. If you are hooking along into a corner, chances are you are using close to all the grip a tyre has. Grip is limited by the friction or restitance it has against the road surface versus the load or enery being applied to the tyre. If the force is equal or less than the grip supplied, the tyre will hold it's line. If the force is greater that the grip, it will start to slide and run wide. If it way to much force, the tyre will let go and the front will tuck, if it's just too much, you get a gentle float into the corner.
Ignore GP or any racers really and think about what you see when you follow one of our quicker Vic members (Mario, Rob, Ron), into corner. I only picked on these three as I have riden behind all these three quickly in both wet and dry. As they enter a corner, the fron t wheel is doing the bulk of the work. It naturally runs wider than the rear, but only slightly as the wider rear tyre plays acouple of tricks that I won't even attempt to explain here. If you look at a bike similar width front and rears, or even a car, you can see it as plain as day when you look carefully.
Mid corner when you have a neutral throttle and steady speed, both wheels are doing the same.
Just pass mid corner when you feed in the power, the back difts or walks wider. Keith Code clearly explains this due to weight transfer shifting toward the rear, and in turn asking it to do more work. (for another thread, KC explains that modern bikes with huge rears need to be accelerated out of corners to cerate enough weight trans fer to give the rear tyre enough contact preasuure to grip properly, think about real working 4wd with their skinny little tyres)
In addition, too much load on a tyre makes it push, and not enough means that it doesn't get pressed into the road hard enough. It all about balance.
Most homolgation type bikes, ie. Zx6/7/10's run too wider a tyre for general riding, but the need these when pulling hard out off corners on effectively one wheel. If you use the formula (Ian, I know your good at formulas) to work out potential grip offer by tyres, you notice that fron and rear is pretty much identical front to back. It' the relationship between width, cross sectional profile, and the wieght likely to be applied to it.
So in conclussion, weight transfers effects handling. The suspension changes cause by weight transfer help handlind. But toomuch weight on a tyre will easily overwhelm it's grip and make it run wide.
For the newbies, the learn to ride book gives you the best piece of advise of all. Do all of your slowing down in a straight line. I feel yopu can experiment to see what is beat for you. And keep experimenting from time to time as your preference may well change as you skills improve.
I hope it's been done with clear enough launguage for everybody to be able to follow.
If your bored of the thread, I understand, but somethings need to be clarified so we can all benefit.
ps. this post is so bloody long I'm not gonna bother trying to fix my typos.