[edit] ISIS

ISIS refers to a type of pattern on the end of a bottom bracket and also what pattern is need on the cranks, for them to be compatible. They come as either ISIS or Square taper. ISIS bottom brackets have a spline pattern, shown in the picture below.

ISIS - International Splined Interface System is a standard produced by many leading crank manufacturer's in an effort to standardise the method by which crank's are attacthed to a bicycle.

ISIS Drive was conceived and executed for the following two reasons:

1To create a common bottom bracket/crankset interface that can be freely shared within the industry. Currently the industry is fragmented and non-standardized with regard to the bottom bracket/crankset interface. This standard seeks to eliminate this problem and thus allow the easy and fully compatible exchange of parts among manufacturers.

2To eliminate or greatly reduce the current problems associated with bottom bracket and crankset interfaces. These problems include incompatibility, lack of crankset position control, insufficient interface strength, and difficulty in determining interface compatibility and conformance.

More information can be seen at the official website.