The same reasoning as for a rear swing-arm construction, can also be applied to a pogo-free front swing-arm construction.
In both cases the load on the spring should remain constant with changing pedaling force.
Therefore at the rear-wheel drive, the spring should get an increasing extracting force through the chain, at an increasing pedaling force.
At the front-wheel drive, the pedaling force should compress the spring through the chain, to get the same effect!
Unfortunately, this requires an artificial construction with a swing arm at the front fork. This makes the complex front-wheel drive even more complicated.
We will suffice here with the outcome of such a reasoning.
With front-wheel drive suspension, pogo is also eliminated for all gears, provided that the middle chainwheel touches the line between the contact point of the front wheel with the road to a point straight above the rear axle, at the height of the center of gravity. The pivot point of the front swing arm fork and the frame must lie somewhere on the line between the point of "touch" and the front axle. See also the graphical model for a frontwheel driven recumbent with frontwheel suspension.
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