Welcome to the

International Spline Interface Standard web site.










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


1. To 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.


2. To 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.


The standard consists of two parts: one governing the interface between the crank and bottom bracket spindle, the other describing a set of standard spindle lengths. The interface portion defines the ISIS Drive interface geometry, insertion depth and control, and attachment bolt specifications. The spindle length section defines the relationship between the bottom bracket and the frame centerline for different standard spindle lengths, thus ensuring the correct position of the crankset relative to the frame centerline.



The ISIS Drive concept began in 1998 when several companies in the industry started talking about how to compete with the “other” spline interface. This “other” interface was protected by several patents, which left most companies with the following choices: 1) never produce a spline interface, 2) produce their own proprietary interface with the result being a mass of non-compatible parts, or 3) work with other companies in the industry to standardize on a common spline interface. Obviously the third choice was the best.


The result of these initial talks among many different companies was … a lot of talk. Thus, at the 1999 Interbike show in Las Vegas, Truvativ, Chris King, and Race Face sat down and began collaborating on a spline interface for bottom brackets and cranks. All three companies immediately recognized the benefit to the industry this interface could have. They had the chance to fix a lot of the problems with the old interface and design something from the ground up. Further, they all agreed to give the resulting design to the public domain and freely provide it to the rest of the industry. The result is the ISIS Drive standard.