Based on the Sommerville tetrahedron, part systems using multiple compatible types can be created that produce more differentiated complex aggregations.

Using an aggregation system based on regular Sommerville-tetra cells, bike frame clusters can be connected along edges.

Combining the concept of bike frames contained in cells with aggregation systems based on the Sommerville-type interconnected structures can be created.

While it is not possible to fill space with regular tetrahedra, there are – according to WOLFRAM – five known irregular space-filling tetrahedral cells, when mirror cells are excluded.

At first we looked at Hill’s tetrahedra and Izidor Hafner “Definitions of Hill’s Tetrahedra” on the Wolfram Demonstrations Project was very helpful in setting up our Grasshopper definitions.

After aggregating regular tetrahedra following different set of rules these tetra-units are replaced by by various bike-frame cluster modules.
Each of these cluster modules is made up of 2-3 bike frames from the scanned set and fitted into a regular tetrahedral container. For this study only copies of one single cluster type are populated throughout the aggregated frameworks replacing the regular tetra-units. This is done assuming that other bike-frames within a certain tolerance range can be used to form the same combinations (possibly with a slightly different clipping at the joint-plate areas). The bigger the inventory of bike frames, the more likely it is to find very similar bike-frames.

_{Fig.1: Bike Cluster TYPE 12 is used for the first study. Dependening on the bike-frames orientation within one tetrahedral cell informed by the respective connection logic (from left to right: face to face, edge to edge, vertex to vertex) the amount of “empty space” locally within one unit varies immensely.}