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Virtual Pivot Point

Virtual Pivot Point technology has put into the hands of engineers endless possibilities to manipulate the wheel path of rear suspension. As mentioned on the Design page, the most optimal path is the S-shaped curve. This is the technology that made HTthis possible.

The design on the right is called the dw-link, and is patented by the same person (Dave Weagle) who designed the Split Pivot displayed on the Four Bar page. It is hard to see, but there is an S-shaped curve here, as mentioned earlier with this design. Unfortunately, there is a drawback to this method of suspension: High forces in a centralized region. The area of the frame near the bottom bracket will be supporting the forces of the suspension at points F and H. This leads to an extremely high stress point. Because this design is more tailored to downhill cyclists and bikes, the extra material required isn't a problem. Some of the bikes that this design is found on will weigh over forty pounds.

The way it works is as the point A moves up, the triangle AGI will rotate clockwise about its own center, as well as rotating about a center up near the front wheel. The link IH will rotate clockwise with point H attached to the frame. Rocker GCF will rotate clockwise about the mounted point F.

The advantages of this technology are endless, and are often untapped. It is possible to adjust the wheel path to make whatever one whishes. The wheel path in the dw-link above looks concentric around a point somewhere near the bottom bracket, or maybe about point I. But if you look closely you will notice that its concavity becomes smaller, deeper into the suspension. Engineer chose this path so that the wheel travels up and back in the beginning of the travel, and will loop back and straighten out deep into the travel. This allows a more active suspension design while under both high and low compression.

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University of Alaska Fairbanks - PHYS 211X - Fall - Copyright Michael Stanfill 2010©