Originally Posted by
jimc101
FSA is just about your only choice if you want any crank in the Octalink format other than Shimano, as fietsbob notes, it was a Shimano design to compete with ISIS, both designs which are now obsolete. They are not compatible with each other, so if you do buy one, make sure it is the correct design.
Not quite correct. Shimano designed and patented the Octalink interface first and for a long time, refused to license the design to other makers. ISIS (International Splined Interface Standard) was created to work around the Shimano patent and was released as a public domain design so anyone could use it and several makers did. As a result, Octalink bottom brackets were generally very good and reliable while ISIS varied all over the place from very good to terrible.
And, yes, they are not at all compatible or interchangable.