Thread: tri-4 bar geometry

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By the way, my theory is that the distance from the center of the left rear tire footprint to the center of the upper shock bolt should be equal to the distance from the left tire footprint to the center of the lower shock bolt. (Of course, the other side is a mirror image) That's based on the arc the axle swings when one tire goes over a bump, and the other doesn't.

I must be missing something, but wouldn't that have the shock leaning outward at the top?

That would lessen the damping action of the shock as the tire comes up on one side.

I can see your point if the measurements were taken at top center of the tire.
That would have the top of the shock leaning inward, which is the generally accepted transverse shock orientation.

Measuring from the top center of the tire and striving for an equal distance on the shock mounting would take care of the shock angle question regardless of shock mounting height.

Color me confused....

What you're missing is one little word that I left out in two places. My bad.

By the way, my theory is that the distance from the center of the left rear tire footprint to the center of the RIGHT upper shock bolt should be equal to the distance from the left tire footprint to the center of the RIGHT lower shock bolt. (Of course, the other side is a mirror image) That's based on the arc the axle swings when one tire goes over a bump, and the other doesn't.

Thanks for clearing it up.

Sure looks like a good rule of thumb to stick away in the memory banks.
I see the "shock angle" question asked quite a bit and most toss out the 30 degree answer.

That works for most installs, but your method takes into account the differences in shock height mounting as well.