Help!!! Bottom Bracket Confusion

[Maculatus]

I am updating a 90's Specialized Rockhopper. I want to fit a Shimano FC- M521 Octalink Crankset. My Frame has a 73mm BB shell. Do I need a 73 X 118mm Bottom Bracket, or a 73 X 126mm?

Any guidance would be much appreciated.

[recordacefromnew]

Neither, 121mm spindle for standard 50mm chainline irrespective of 68/73mm bb shell width version, according to http://www.shimano.com/media/techdocs/c ... 657937.pdf

Do make sure you get an Octalink v2, not Octalink v1 bb. I think they are available in either the ES25 or ES51 series.

[Maculatus]

Thank you for the help!