In another answer on suspension spring load calculations, @Criggie provided some examples of different suspension designs, 1) the standard four-bar, and 2) the twin-link four-bar:

enter image description here enter image description here

Clearly there second has a more complicated linkage, but what is the twin-link four-bar suspension design trying to solve?

The twin-link seems to have a bigger virtual pivot point and the magnified axle path seems to swerve less laterally, but it's hard to tell from the exaggerated diagram.

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    Changes to effective chain stay length affecting the pedaling action and reduce bob caused by pedaling. Less important now days as shocks are far more effective at dampening pedal bob and braking forces while remaining compliant to bumps than early days. – mattnz Mar 31 '18 at 21:13
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    Yeah I wondered something similar. The second picture's "Virtual Pivot Point" line makes no sense, and the "magnified axle path" appears the same in both images. – Criggie Mar 31 '18 at 23:51
  • The top image appears to be a lever with different possible ratios, whereas the second image depends more on the shock/spring characteristics. So the first image could use a different rate spring by swapping out the grey "lever" arms where the second is pretty stuck with just whatever adjustment the shock has. – Criggie Mar 31 '18 at 23:56
  • Yeah, to me it’s not clear which is supposed to be the superior design and why. Thus the question. – RoboKaren Apr 1 '18 at 3:15

The images originally came from the following article:

An updated article was released last year with a mountain of information about suspension designs:

I suspect the twin link system was a way to circumnavigate the patent on the Horst link whilst providing similar suspension performance.

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    Can you expand this answer more so that we don’t have to go to the link? This helps mitigate against link rot. – RoboKaren Apr 2 '18 at 15:22

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