Quote:
Originally Posted by Michael Moore
.....Jim, running the swing arm as you've drawn in may have been avoided by the Gurneys because of poor squat/anti-squat chain geometry. I did a quick model with a steeply angled swing arm and matching sprocket and it seemed to have a lot of squat under acceleration. With an already low bike having significant pro-squat characteristics could be a problem. You'd also have to move the top damper mount forward to avoid a falling rate, and that would then intrude on the rider space....
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Michael,
I thought about this as well, in that the change in swing-arm inclination *could* affect the amount of squat.
The same is true of shaft drive bikes, but this is another topic for discussion.
However, being that my intent with a FF design, is to get better mileage, then acceleration and the amount of rear squat is pretty much a moot point, within reason.
A side note, you probably still remember the ATAC sprocket that was sold for a few years, way back in the late 70's if memory serves. These sprockets were supposed to help with the topic you speak of, but then they disappeared. Maybe they did not *fix* a problem after all?? Who knows.
To get a rising-rate shock setup, I usually think of the shock top being inclinated at about 45deg or so from horizontal, not the almost upright position seen in the Yamaha above. From a purely technical standpoint, you are correct, but I'm not sure it would matter enough for a fuel sipper.
Jim.