ISIS drive?
 

What is ISIS drive. Is this just the aftermarket form of shimano octalink splined drive?

ISIS is an international-standard for bottom brackets and cranksets. It is in the style of the Shimano Octalink system but the specs are slightly different, to avoid patent infringements. It's much stiffer/better than tapered bottom brackets/cranks, similar to Shimano Octalink. ISIS bottom brackets are NOT compatitble with Shimano Cranksets and vice-versa, so you need an ISIS crank to match an ISIS BB.

I like my ISIS cranks.

Both of my road bikes have Truvativ ISIS cranks. I love the stiffness!

From www.sheldonbrown.com

The I.S.I.S. (International Spline Interface Standard) splined bottom bracket system is a response to the Shimano splined bottom brackets, supported by a number of independent makers of cranks and/or bottom brackets. This is being pushed as an alternative to Shimano's proprietary spline pattern.