Maybe Telelever keeps a reasonably constant rake and trail as it moves? We'd need someone with a cad machine to tell us. .
It's a long time ago now and I've lost the link but this was posted on pelican , and also I think, Gromit posted up photos with the front shock removed, at different ride heights illustrating what happens .
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1999 R1100s (mandarin) '
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2019 CB125F Honda.
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Thank you very much for taking the time to do that.
I actually thought the rake might stay constant but it seems that it gets greater as front susp compresses. The cossalter animation doesn't really help as it moves too fast to really see what happens in detail. One thing it does illustrate though, is how we have to re orientate the horizontal as the front compresses, which adjusts the figures. An easy thing to miss without seeing the animation.
Still, if the rake gets greater as the A arm swings up, then how can the rockster version, with the shock sat lowersteepen the rake? I'm not referring to the mods which shorten the centre distance.
Then again rake is a line drawn between the top and bottom pivots? As the arm swings up, you might assume this line would get steeper? Unless the arm starts off by pointing downwards.
You guys are literally years ahead of me, so beggin yer pardon if this is stating the obvious. For me, it is definitely a step forwards in understanding HOW it happens. Assuming the following is correct.
As has been said, the rake angle angle will actually increase as the front susp is compressed. But how? This is is so counter intuitive. And even thinking about the A arm moving upwards, it seems (to me) at first that surely the angle of the line drawn between the upper and lower pivots should steepen.
Put pen to paper. Even a few hand drawn lines and curves yields the answer. I think!
Draw three dots in space. One to represent the A arm main pivot. One to represent the fork top yoke ball joint. The other to represent the lower ball joint. A line between the two ball joint positions is the rake angle, yes? Draw an arc to represent the sweep of the lower ball joint. Draw a line from the top ball joint touching the arc at a tangent. Draw a line from the top ball joint to the lower ball joint with bike static. This illustrates, to me at least, how the rake angle can increase as the suspension compresses.
It seems (to me) that the A arm would have to swing upwards past the point where the tangent touches for the rake angle to start to lessen back. The A arm would have to swing an awful long way up for the angle to return to the same as it started in the static position.
Imagine a line between the upper and lower steering ball joints. Imagine a line between the A arm main pivots and the lower steering ball joint.
If the angle between those lines is less than 90 degrees in the static position, then the rake angle will increase as the front suspension compresses. If the angle is 90 degrees or more, then the rake angle will decrease as the front suspension compresses.
